SpringMVC基础之三->SpringMVC的使用

时间  2021-04-27
标签 javascript html java jquery 程序员 web ajax spring apache json 栏目 Spring 繁體版
原文   原文链接

一、SpringMVC的返回JSON数据

​ 到目前为止咱们编写的全部Controller的方法的返回值都是String类型，可是你们应该都知道，咱们有时候数据传递特别是在ajax中，咱们返回的数据常常须要使用json，那么如何来保证返回的数据的是json格式呢？使用@ResponseBody注解javascript

pom.xmlhtml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mashibing</groupId>
    <artifactId>springmv_ajax</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-web -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>5.2.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.3.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.0</version>
            <scope>provided</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.10.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.10.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.10.3</version>
        </dependency>
    </dependencies>
</project>

springmvc.xmljava

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:component-scan base-package="com.mashibing"></context:component-scan>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/page/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
    <mvc:default-servlet-handler></mvc:default-servlet-handler>
    <mvc:annotation-driven></mvc:annotation-driven>
</beans>

JsonController.javajquery

package com.mashibing.controller;

import com.mashibing.bean.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

@Controller
public class JsonController {

    @ResponseBody
    @RequestMapping("/json")
    public List<User> json(){
        List<User> list = new ArrayList<User>();
        list.add(new User(1,"zhangsan",12,"男",new Date(),"1234@qq.com"));
        list.add(new User(2,"zhangsan2",12,"男",new Date(),"1234@qq.com"));
        list.add(new User(3,"zhangsan3",12,"男",new Date(),"1234@qq.com"));
        return list;
    }
}

User.java程序员

package com.mashibing.bean;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonIgnore;

import java.util.Date;

public class User {

    private Integer id;
    private String name;
    private Integer age;
    private String gender;
    @JsonFormat( pattern = "yyyy-MM-dd")
    private Date birth;
    @JsonIgnore
    private String email;

    public User() {
    }

    public User(Integer id, String name, Integer age, String gender, Date birth, String email) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.birth = birth;
        this.email = email;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Date getBirth() {
        return birth;
    }

    public void setBirth(Date birth) {
        this.birth = birth;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", gender='" + gender + '\'' +
                ", birth=" + birth +
                ", email='" + email + '\'' +
                '}';
    }
}

同时@ResponseBody能够直接将返回的字符串数据做为响应内容web

package com.mashibing.controller;

import com.mashibing.bean.User;
import org.springframework.http.HttpEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class OtherController {
    @ResponseBody
    @RequestMapping("/testResponseBody")
    public String testResponseBody(){
        return "<h1>success</h1>";
    }
}

二、发送ajax请求获取json数据

ajax.jspajax

<%@ page import="java.util.Date" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script type="text/javascript" src="script/jquery-1.9.1.min.js"></script>
</head>
<%
    pageContext.setAttribute("ctp",request.getContextPath());
%>
<body>
<%=new Date()%>
<a href="${ctp}/json">获取用户信息</a>
<div>

</div>
<script type="text/javascript">
    $("a:first").click(function () {
        $.ajax({
            url:"${ctp}/json",
            type:"GET",
            success:function (data) {
                console.log(data)
                $.each(data,function() {
                    var user = this.id+"--"+this.name+"--"+this.age+"--"+this.gender+"--"+this.birth+"--"+this.email;
                    $("div").append(user+'<br/>');
                })
            }
        });
        return false;
    });
</script>
</body>
</html>

三、使用@RequestBody获取请求体信息

testOther.jspspring

<%--
  Created by IntelliJ IDEA.
  User: root
  Date: 2020/3/13
  Time: 15:04
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<%
    pageContext.setAttribute("ctp",request.getContextPath());
%>
<head>
    <title>Title</title>
</head>
<body>
<form action="${ctp}/testRequestBody" method="post" enctype="multipart/form-data">
    <input name="username" value="zhangsan"><br>
    <input name="password" value="123456"><br>
    <input type="file" name="file" ><br>
    <input type="submit"><br>
</form>
</body>
</html>

OtherController.javaapache

package com.mashibing.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class OtherController {

    @RequestMapping("/testRequestBody")
    public String testRequestBody(@RequestBody String body){
        System.out.println("请求体："+body);
        return "success";
    }
}

同时@RequestBody可以接受json格式的请求数据：json

testOther.jsp

<%--
  Created by IntelliJ IDEA.
  User: root
  Date: 2020/3/13
  Time: 15:04
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<script type="text/javascript" src="script/jquery-1.9.1.min.js"></script>
<html>
<%
    pageContext.setAttribute("ctp",request.getContextPath());
%>
<head>
    <title>Title</title>
</head>
<body>
<form action="${ctp}/testRequestBody" method="post" enctype="multipart/form-data">
    <input name="username" value="zhangsan"><br>
    <input name="password" value="123456"><br>
    <input type="file" name="file" ><br>
    <input type="submit"><br>
</form>
<hr/>
<a href="${ctp}/testRequestJson">发送json数据</a>
<script type="text/javascript">
    $("a:first").click(function () {
        var user = {id:"1",name:"zhangsan",age:"12",gender:"男",birth:"2020-3-13",email:"123@qq.com"};
        var userJson = JSON.stringify(user);
       $.ajax({
           url:"${ctp}/testRequestJson",
           type:"POST",
           data:userJson,
           contentType:"application/json",
           success:function (data) {
               alert(data);
           }
       });
       return false;
    });
</script>
</body>
</html>

OtherController.java

package com.mashibing.controller;

import com.mashibing.bean.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class OtherController {

    @RequestMapping("/testRequestBody")
    public String testRequestBody(@RequestBody String body){
        System.out.println("请求体："+body);
        return "success";
    }

    @RequestMapping("/testRequestJson")
    public String testRequestBody(@RequestBody User user){
        System.out.println("对象："+user);
        return "success";
    }
}

在接受请求的时候还可使用HttpEntity对象，用来接受参数，能够获取请求头信息。

package com.mashibing.controller;

import com.mashibing.bean.User;
import org.springframework.http.HttpEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class OtherController {

    @RequestMapping("/testHttpEntity")
    public String testRequestBody(HttpEntity<String> httpEntity){
        System.out.println(httpEntity);
        return "success";
    }
}

四、使用RespsonseEntity能够用来定制响应内容

package com.mashibing.controller;

import com.mashibing.bean.User;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class OtherController {

    @RequestMapping("/testResponseEntity")
    public ResponseEntity<String> testResponseEntity(){

        String body = "<h1>hello</h1>";
        MultiValueMap<String,String> header = new HttpHeaders();
        header.add("Set-Cookie","name=zhangsan");
        return  new ResponseEntity<String>(body,header, HttpStatus.OK);
    }
}

五、文件下载

package com.mashibing.controller;

import com.mashibing.bean.User;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

@Controller
public class OtherController {

    @RequestMapping("/download")
    public ResponseEntity<byte[]> download(HttpServletRequest request) throws Exception {
        //获取要下载文件的路径及输入流对象
        ServletContext servletContext = request.getServletContext();
        String realPath = servletContext.getRealPath("/script/jquery-1.9.1.min.js");
        FileInputStream fileInputStream = new FileInputStream(realPath);

        byte[] bytes = new byte[fileInputStream.available()];
        fileInputStream.read(bytes);
        fileInputStream.close();
        //将要下载文件内容返回
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.set("Content-Disposition","attachment;filename=jquery-1.9.1.min.js");
        return  new ResponseEntity<byte[]>(bytes,httpHeaders,HttpStatus.OK);
    }
}

六、文件上传

​ Spring MVC 为文件上传提供了直接的支持，这种支持是经过即插即用的 MultipartResolver 实现的。Spring 用 Jakarta Commons FileUpload 技术实现了一个 MultipartResolver 实现类：CommonsMultipartResovler

​ Spring MVC 上下文中默认没有装配 MultipartResovler，所以默认状况下不能处理文件的上传工做，若是想使用 Spring 的文件上传功能，需如今上下文中配置 MultipartResolver。

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mashibing</groupId>
    <artifactId>springmvc_upload</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-web -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>5.2.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.0</version>
            <scope>provided</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.10.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.10.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.10.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-io/commons-io -->
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>
    </dependencies>
</project>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <filter>
        <filter-name>encoding</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <mvc:default-servlet-handler></mvc:default-servlet-handler>
    <mvc:annotation-driven></mvc:annotation-driven>
    <context:component-scan base-package="com.mashibing"></context:component-scan>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/page/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="UTF-8"></property>
        <property name="maxUploadSize" value="1024000"></property>
    </bean>
</beans>

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: root
  Date: 2020/3/13
  Time: 17:00
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  <form action="testUpload" method="post" enctype="multipart/form-data">
    文件: <input type="file" name="file"/><br><br>
    描述: <input type="text" name="desc"/><br><br>
    <input type="submit" value="提交"/>
  </form>
  </body>
</html>

UploadHandler.java

package com.mashibing.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

@Controller
public class UploadHandler {

    @RequestMapping(value = "/testUpload", method = RequestMethod.POST)
    public String testUpload(@RequestParam(value = "desc", required = false) String desc, @RequestParam("file") MultipartFile multipartFile) throws IOException {
        System.out.println("desc : " + desc);
        System.out.println("OriginalFilename : " + multipartFile.getOriginalFilename());
        multipartFile.transferTo(new File("D:\\file\\"+multipartFile.getOriginalFilename()));

        return "success"; //增长成功页面: /views/success.jsp
    }
}

success.jsp

<%--
  Created by IntelliJ IDEA.
  User: root
  Date: 2020/3/13
  Time: 17:03
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
success
</body>
</html>

若是是多文件上传，那么又改如何处理呢？

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: root
  Date: 2020/3/13
  Time: 17:00
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  <form action="testUpload" method="post" enctype="multipart/form-data">
    文件: <input type="file" name="file"/><br><br>
    文件: <input type="file" name="file"/><br><br>
    文件: <input type="file" name="file"/><br><br>
    描述: <input type="text" name="desc"/><br><br>
    <input type="submit" value="提交"/>
  </form>
  </body>
</html>

UploadHandler.java

package com.mashibing.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

@Controller
public class UploadHandler {

    @RequestMapping(value = "/testUpload", method = RequestMethod.POST)
    public String testUpload(@RequestParam(value = "desc", required = false) String desc, @RequestParam("file") MultipartFile[] multipartFile) throws IOException {
        System.out.println("desc : " + desc);
        for (MultipartFile file : multipartFile) {
            if (!file.isEmpty()) {
                System.out.println("OriginalFilename : " + file.getOriginalFilename());
                file.transferTo(new File("D:\\file\\" + file.getOriginalFilename()));
            }
        }

        return "success"; //增长成功页面: /views/success.jsp
    }
}

七、Springmvc拦截器

​ SpringMVC提供了拦截器机制，容许运行目标方法以前进行一些拦截工做或者目标方法运行以后进行一下其余相关的处理。自定义的拦截器必须实现HandlerInterceptor接口。
image.png

​ preHandle()：这个方法在业务处理器处理请求以前被调用，在该方法中对用户请求 request 进行处理。若是程序员决定该拦截器对请求进行拦截处理后还要调用其余的拦截器，或者是业务处理器去进行处理，则返回true；若是程序员决定不须要再调用其余的组件去处理请求，则返回false

​ postHandle()：这个方法在业务处理器处理完请求后，可是DispatcherServlet 向客户端返回响应前被调用，在该方法中对用户请求request进行处理。

​ afterCompletion()：这个方法在DispatcherServlet彻底处理完请求后被调用，能够在该方法中进行一些资源清理的操做。

一、自定义第一个拦截器

MyFirstInterceptor.java

package com.mashibing.interceptor;


import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyFirstInterceptor implements HandlerInterceptor {
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println(this.getClass().getName()+"------->preHandle");
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println(this.getClass().getName()+"------->postHandle");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println(this.getClass().getName()+"------->afterCompletion");
    }
}

TestInterceptorController.java

package com.mashibing.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class TestInterceptorController {

    @RequestMapping("test01")
    public String test01(){
        System.out.println("test01");
        return "success";
    }
}

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <mvc:default-servlet-handler></mvc:default-servlet-handler>
    <mvc:annotation-driven></mvc:annotation-driven>
    <context:component-scan base-package="com.mashibing"></context:component-scan>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/page/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
    <mvc:interceptors>
        <bean class="com.mashibing.interceptor.MyFirstInterceptor"></bean>
    </mvc:interceptors>
</beans>

success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<% System.out.println("success.jsp");%>
success
</body>
</html>

​ 经过运行结果可以发现拦截器的执行顺序以下：
image.png

​ 能够看到先执行拦截器的preHandle方法----》执行目标方法----》执行拦截器的postHandle方法----》执行页面跳转----》执行拦截器的afterCompletion方法

​ 在配置拦截器的时候有两个须要注意的点：

​ 一、若是prehandle方法返回值 为false，那么意味着不放行，那么就会形成后续的全部操做都中断

​ 二、若是执行到方法中出现异常，那么后续流程不会处理可是afterCompletion方法会执行

二、定义多个拦截器

​ 再添加另一个拦截器

MySecondInterceptor.java

package com.mashibing.interceptor;


import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MySecondInterceptor implements HandlerInterceptor {
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println(this.getClass().getName()+"------->preHandle");
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println(this.getClass().getName()+"------->postHandle");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println(this.getClass().getName()+"------->afterCompletion");
    }
}

看到以下执行顺序：

image.png

调整两个拦截器的配置顺序：

image.png

你们能够看到对应的效果，谁先执行取决于配置的顺序。

​ 拦截器的preHandle是按照顺序执行的

​ 拦截器的postHandle是按照逆序执行的

​ 拦截器的afterCompletion是按照逆序执行的

​ 若是执行的时候核心的业务代码出问题了，那么已经经过的拦截器的afterCompletion会接着执行。

八、拦截器跟过滤器的区别

​ 一、过滤器是基于函数回调的，而拦截器是基于java反射的

​ 二、过滤器依赖于servlet容器，而拦截器不依赖与Servlet容器

​ 三、过滤器几乎对全部的请求都起做用，而拦截器只能对action请求起做用

​ 四、拦截器能够访问action的上下文，而过滤器不能够

​ 五、在controller的生命周期中，拦截器能够屡次调用，而过滤器只能在web容器初始化的时候初始化一次，后续匹配的全部请求都会通过过滤器来进行过滤

image.png

image.png

九、SpringMVC的国际化操做

​ 在平常工做中，若是你的网站须要给不一样语言地区的人进行查看，此时就须要使用国际化的基本操做，springmvc的国际化操做比较容易。

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: root
  Date: 2020/3/13
  Time: 17:00
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  <a href="i18n">国际化页面登陆</a>
  </body>
</html>

login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1><fmt:message key="welcomeinfo"/></h1>
<form action="login" method="post" >
    <fmt:message key="username"/>: <input type="text" name="username"/><br><br>
    <fmt:message key="password"/>: <input type="password" name="password"/><br><br>
    <input type="submit" value="<fmt:message key="loginBtn"/>"/>
</form>
</body>
</html>

I18nController.java

package com.mashibing.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class I18nController {

    @RequestMapping("i18n")
    public String i18n(){
        return "login";
    }
}

login_en_US.properties

welcomeinfo=welcome to mashibing.com
username=USERNAME
password=PASSWORD
loginBtn=LOGIN

login_zh_CN.properties

welcomeinfo=欢迎进入马士兵教育
username=用户名
password=密码
loginBtn=登陆

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <mvc:default-servlet-handler></mvc:default-servlet-handler>
    <mvc:annotation-driven></mvc:annotation-driven>
    <context:component-scan base-package="com.mashibing"></context:component-scan>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/page/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
    <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
        <property name="basename" value="login"></property>
    </bean>
</beans>

​ 其实SpringMVC中国际化的处理很是简单，就是按照浏览器所带来的语言信息决定的。

Locale locale = request.getLocale();//获取浏览器的区域信息

在DispatcherServlet中会包含一个组件，用来专门获取区域信息

image.png

image.png

经过图片可以发现，默认调用的是org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver类

在程序中能够获取Locale的相关信息：

package com.mashibing.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import java.util.Locale;

@Controller
public class I18nController {

    @Autowired
    private MessageSource messageSource;

    @RequestMapping("i18n")
    public String i18n(Locale locale){
        System.out.println(locale);
        String username = messageSource.getMessage("username", null, locale);
        System.out.println(username);
        return "login";
    }
}

十、经过超连接来切换国际化

login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1><fmt:message key="welcomeinfo"/></h1>
<form action="login" method="post" >
    <fmt:message key="username"/>: <input type="text" name="username"/><br><br>
    <fmt:message key="password"/>: <input type="password" name="password"/><br><br>
    <input type="submit" value="<fmt:message key="loginBtn"/>"/>
    <a href="i18n?locale=zh_CN">中文</a><a href="i18n?locale=en_US">英文</a>
</form>
</body>
</html>

MyLocaleResolver.java

package com.mashibing;

import org.springframework.web.servlet.LocaleResolver;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Locale;

public class MyLocaleResolver implements LocaleResolver {
    /**
     * 解析并返回locale
     * @param request
     * @return
     */
    @Override
    public Locale resolveLocale(HttpServletRequest request) {
        Locale locale = null;
        String localeStr = request.getParameter("locale");
        if(localeStr!=null && ! "".equals(localeStr)){
            locale = new Locale(localeStr.split("_")[0],localeStr.split("_")[1]);
        }else{
            locale = request.getLocale();
        }
        return locale;
    }

    /**
     * 不支持设置locale的信息
     * @param request
     * @param response
     * @param locale
     */
    @Override
    public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
        throw new UnsupportedOperationException(
                "Cannot change HTTP accept header - use a different locale resolution strategy");
    }
}

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<mvc:default-servlet-handler></mvc:default-servlet-handler>
<mvc:annotation-driven></mvc:annotation-driven>
<context:component-scan base-package="com.mashibing"></context:component-scan>

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/page/"></property>
    <property name="suffix" value=".jsp"></property>
</bean>
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
    <property name="basename" value="login"></property>
</bean>
    <!--配置区域信息解析器-->
    <bean id="localeResolver" class="com.mashibing.MyLocaleResolver"></bean>
</beans>

除了能够自定义区域信息解析器以外，咱们还可使用SpringMVC中自带的SessionLocaleResolver:

I18nController.java

package com.mashibing.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.i18n.SessionLocaleResolver;

import javax.servlet.http.HttpSession;
import java.util.Locale;

@Controller
public class I18nController {

    @Autowired
    private MessageSource messageSource;

    @RequestMapping("i18n")
    public String i18n(@RequestParam(value = "locale",defaultValue = "zh_CN") String localeStr,Locale locale, HttpSession session){

        Locale l = null;
        if(localeStr!=null && ! "".equals(localeStr)){
            l = new Locale(localeStr.split("_")[0],localeStr.split("_")[1]);
        }else{
            l = locale;
        }
        session.setAttribute(SessionLocaleResolver.class.getName() + ".LOCALE",l);
        return "login";
    }
}

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<mvc:default-servlet-handler></mvc:default-servlet-handler>
<mvc:annotation-driven></mvc:annotation-driven>
<context:component-scan base-package="com.mashibing"></context:component-scan>

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/page/"></property>
    <property name="suffix" value=".jsp"></property>
</bean>
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
    <property name="basename" value="login"></property>
</bean>
    <!--配置区域信息解析器-->
<!--    <bean id="localeResolver" class="com.mashibing.MyLocaleResolver"></bean>-->
    <bean id="localeResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver"></bean>
</beans>

使用LocaleChangeInterceptor来实现国际化：

springmvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<mvc:default-servlet-handler></mvc:default-servlet-handler>
<mvc:annotation-driven></mvc:annotation-driven>
<context:component-scan base-package="com.mashibing"></context:component-scan>

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/page/"></property>
    <property name="suffix" value=".jsp"></property>
</bean>

<!--    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">-->
<!--        <property name="defaultEncoding" value="UTF-8"></property>-->
<!--        <property name="maxUploadSize" value="1024000"></property>-->
<!--    </bean>-->
<!--    <mvc:interceptors>-->
<!--        <bean class="com.mashibing.interceptor.MySecondInterceptor"></bean>-->
<!--        <bean class="com.mashibing.interceptor.MyFirstInterceptor"></bean>-->
<!--    </mvc:interceptors>-->
<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
    <property name="basename" value="login"></property>
</bean>
<!--配置区域信息解析器-->
<!--    <bean id="localeResolver" class="com.mashibing.MyLocaleResolver"></bean>-->
<bean id="localeResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver"></bean>
    <mvc:interceptors>
        <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor"></bean>
    </mvc:interceptors>
</beans>

I18nController.java

package com.mashibing.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.i18n.SessionLocaleResolver;

import javax.servlet.http.HttpSession;
import java.util.Locale;

@Controller
public class I18nController {

    @Autowired
    private MessageSource messageSource;

    @RequestMapping("i18n")
    public String i18n(@RequestParam(value = "locale",defaultValue = "zh_CN") String localeStr,Locale locale, HttpSession session){

//        Locale l = null;
//        if(localeStr!=null && ! "".equals(localeStr)){
//            l = new Locale(localeStr.split("_")[0],localeStr.split("_")[1]);
//        }else{
//            l = locale;
//        }
//        session.setAttribute(SessionLocaleResolver.class.getName() + ".LOCALE",l);
        return "login";
    }
}

十一、SpringMVC异常处理机制

​ 在SpringMVC中拥有一套很是强大的异常处理机制，SpringMVC经过HandlerExceptionResolver处理程序的异常，包括请求映射，数据绑定以及目标方法的执行时发生的异常。

在容器启动好，进入DispatcherServlet以后，会对HandlerExceptionResolver进行初始化操做：

会默认的从DispatcherServlet.properties中找到对应的异常处理类：

#默认的处理类
org.springframework.web.servlet.HandlerExceptionResolver=
#处理@ExceptionHandler
org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver,\
#处理@ResponseStatus，给自定义异常使用
org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver,\
#判断是不是SpringMVC自带异常
org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver

本身定义异常处理方式：

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
<a href="exception1">本身处理异常</a>
  </body>
</html>

ExceptionController.java

package com.mashibing.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import javax.jws.WebParam;

@Controller
public class ExceptionController {

    @RequestMapping("exception1")
    public String exception(){
        System.out.println("exception.......");
        System.out.println(10/0);
        return "success";
    }

    @ExceptionHandler(value = {ArithmeticException.class})
    public ModelAndView handlerException(Exception exception){
        ModelAndView mv = new ModelAndView();
        mv.setViewName("error");
        mv.addObject("ex",exception);
        return mv;
    }
}

error.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
个人出错页面：
错误信息：${ex}
</body>
</html>

​ 在一个类中可能会包含多个异常的处理方法，在不一样的方法上可使用不一样范围的异常，在查找的时候会优先调用范围小的异常处理；

package com.mashibing.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import javax.jws.WebParam;

@Controller
public class ExceptionController {

    @RequestMapping("exception1")
    public String exception(){
        System.out.println("exception.......");
        System.out.println(10/0);
        return "success";
    }

    @ExceptionHandler(value = {ArithmeticException.class})
    public ModelAndView handlerException1(Exception exception){
        System.out.println("handlerException1........");
        ModelAndView mv = new ModelAndView();
        mv.setViewName("error");
        mv.addObject("ex",exception);
        return mv;
    }

    @ExceptionHandler(value = {Exception.class})
    public ModelAndView handlerException2(Exception exception){
        System.out.println("handlerException2........");
        ModelAndView mv = new ModelAndView();
        mv.setViewName("error");
        mv.addObject("ex",exception);
        return mv;
    }
}

​ 在不一样的类中可能会包含不一样的异常处理，所以咱们须要定义一个全局的异常控制器,使用@ControllerAdvice注解标注，若是本类跟全局都有相关异常的处理，那么会优先使用本类的。

package com.mashibing.controller;

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;

@ControllerAdvice
public class MyGlobalExceptionHandler {
    @ExceptionHandler(value = {ArithmeticException.class})
    public ModelAndView handlerException1(Exception exception){
        System.out.println("handlerException1........");
        ModelAndView mv = new ModelAndView();
        mv.setViewName("error");
        mv.addObject("ex",exception);
        return mv;
    }
}

@ResponseStatus的使用：

​ @ResponseStatus能够标注到方法上，可是标注在方法以后可能致使该方法没法被访问，所以更多的是在自定义类上

package com.mashibing.controller;

import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.servlet.ModelAndView;

import javax.jws.WebParam;

@Controller
public class ExceptionController {

    @ResponseStatus(reason = "不知道什么缘由，反正错误",value = HttpStatus.NOT_ACCEPTABLE)
    @RequestMapping("exception1")
    public String exception(){
        System.out.println("exception.......");
        return "success";
    }
}

​ @ResponseStatus做用在类上

UserNameException.java

package com.mashibing.controller;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

@ResponseStatus(reason = "名字不是admin",value = HttpStatus.NOT_ACCEPTABLE)
public class UserNameException extends RuntimeException {
}

ExceptionController.java

package com.mashibing.controller;

import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.servlet.ModelAndView;

import javax.jws.WebParam;

@Controller
public class ExceptionController {
    @RequestMapping("exception1")
    public String exception(){
        System.out.println("exception.......");
        return "success";
    }
    @RequestMapping("exception2")
    public String exception2(String username){
        System.out.println("exception2222.......");
        if ("admin".equals(username)){
            return "success";
        }else{
            throw new UserNameException();
        }
    }
}

springmvc自定义的异常：

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: root
  Date: 2020/3/13
  Time: 17:00
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
<a href="exception1">本身处理异常</a>
<a href="exception2?username=zhangsan">自定义异常处理</a>
<a href="exception3">Springmvc本身异常处理</a>
  </body>
</html>

ExceptionController.java

package com.mashibing.controller;

import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.servlet.ModelAndView;

import javax.jws.WebParam;

@Controller
public class ExceptionController {

    @RequestMapping("exception1")
    public String exception(){
        System.out.println("exception.......");
        return "success";
    }
    @RequestMapping("exception2")
    public String exception2(String username){
        System.out.println("exception2222.......");
        if ("admin".equals(username)){
            return "success";
        }else{
            throw new UserNameException();
        }
    }

    @RequestMapping(value = "exception3",method = RequestMethod.POST)
    public String exception3(String username){
        System.out.println("exception3.......");
            return "success";
    }
}
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