Springmvc中ajax与jason应用

时间  2019-11-13
标签 springmvc ajax jason 应用 栏目 Spring 繁體版
原文   原文链接

Springmvc中ajax与jason应用

相关依赖包

json数据转换的jar包javascript

jackson-annotations-2.5.4
jackson-core-2.5.4
jackson-databind-2.5.4html

spring以及spring的依赖包java

bean context aop context core web webmvc expressionjquery

未涉及json的ajax请求

简单的表单验证git

Controller层java代码

@Controller
public class AjaxCtrl {
    @RequestMapping("/toAjax.do")
    public String toAjax() {
        return "ajax";
    }
    @RequestMapping("/ajax.do")
    @ResponseBody
    public void ajaxJson(@RequestParam("name")String name,HttpServletResponse resp) throws IOException {
        PrintWriter out = resp.getWriter();
        if(name.equals("hm"))
            out.print("该用户已注册");
        else
            out.print("该用户可以使用");
    }

注意点：github

  • 在手动调用getWriter()方法时不能够再添加返回值，不然tomcat会报错（getWriter()方法已存在）。由于在返回值处容器会自动调用getWriter()方法来输出内容，而检测到前面getWriter()已经被调用过，产生冲突。
  • 解决：1. 像上面的代码不给出返回值；2. resp.reset(); resp.setContentType("text/html; charset=utf-8"); out.flush; out.close();

  • @ResponseBody会将返回的数据自动转换为json格式的数据web

    相关jsp代码：ajax.jsp

<script src="${pageContext.request.contextPath }/js/jquery-2.1.0.min.js" type="text/javascript"></script>
</head>
<body>
    姓名：<input type="text" id="field" name="name" /><span id="txt"></span>
    <script type="text/javascript">
        $("#field").blur(function(){
            $.post("ajax.do",{'name':$('#field').val()},function(result){
                $("#txt").html(result);
            });
        });
    </script>
</body>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
    id="WebApp_ID" version="3.1">
    <display-name>springmvc_ajax</display-name>
    <filter>
        <filter-name>characterencoding</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>characterencoding</filter-name>
        <url-pattern>*.do</url-pattern>
    </filter-mapping>
    <servlet>
        <servlet-name>ajax</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>ajax</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
</web-app>

涉及json格式数据的ajax请求

Controller层java代码

@RequestMapping("/toAjaxJson.do")
    public String toAjaxJson() {
        return "ajaxJson";
    }
    @RequestMapping("/ajaxJson.do")
    @ResponseBody
    public List<User> ajaxJson() {
        List<User> list = new ArrayList<User>();
        list.add(new User(1, "xb", "123"));
        list.add(new User(2, "xc", "234"));
        list.add(new User(3, "xd", "345"));
        list.add(new User(4, "xa", "456"));
        return list;
    }

相关jsp代码：ajaxJson.jsp

<input type="button" id="btn" value="获取json数据">
    <table  width="80%" align="center">
        <tr>
            <th>编号</th>
            <th>姓名</th>
            <th>密码</th>
        </tr>
        <tbody id="content"></tbody>
    </table>
    <script type="text/javascript">
    $(function(){
        $("#btn").click(function(){
            $.get("ajaxJson.do",function(list){
                var field = "";
                for (var i = 0; i < list.length; i++) {
                    field +="<tr><td>"+list[i].id+"</td>"+"<td>"+list[i].name+"</td>"+"<td>"+list[i].passwd+"</td></tr>";
                }
                $("#content").html(field);
            });
        });
    });
    </script>

springmvc的核心配置文件：mvc.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 http://www.springframework.org/schema/context/spring-context-4.1.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd">
    <!-- 开启mvc的注解 -->
    <mvc:annotation-driven />
    <!-- 扫描包 -->
    <context:component-scan base-package="com.zrm.controller"></context:component-scan>
    <!-- 配置视图解析器 -->
    <bean id="InternalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/views/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
    <bean id="stringConverter" class="org.springframework.http.converter. StringHttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/plain;charset=UTF-8</value>
            </list>
        </property>
    </bean>
    <bean id="jsonConverter" class="org.springframework.http.converter.json. "></bean>
    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="stringConverter"/>
                <ref bean="jsonConverter"/>
            </list>
        </property>
    </bean> 
</beans>

相关类的介绍

StringHttpMessageConverter

官方文档：
An HttpMessageConverter implementation that can read and write Strings from the HTTP request and response. By default, this converter supports all text media types (text/*), and writes with a Content-Type of text/plain.ajax

译文：
一种HttpMessageConverter能够从HTTP请求和响应中读取和写入字符串的实现。默认状况下，此转换器支持全部文字媒体类型(text/*)，并用Content-Type中的text/plain类型。spring

MappingJackson2HttpMessageConverter

官方文档：
An HttpMessageConverter implementation that can read and write JSON using Jackson’s ObjectMapper. JSON mapping can be customized as needed through the use of Jackson’s provided annotations. When further control is needed, a custom ObjectMapper can be injected through the ObjectMapper property for cases where custom JSON serializers/deserializers need to be provided for specific types. By default this converter supports ( application/json).express

译文：
一个HttpMessageConverter能够使用Jackson库提供的ObjectMapper类来读取和写入json格式的数据。能够根据须要经过使用Jackson库提供的注解来自定义XML映射。当须要进一步控制时，XmlMapper 能够经过ObjectMapper属性注入自定义，以用于须要为特定类型提供自定义XML序列化器/反序列化器的状况。默认状况下，此转换器支持（application/xml）。

ObjectMapper是Jackson库的主要类，他提供的一些功能用于将Java对象转换为符合jason结构的字符串。

AnnotationMethodHandlerAdapter

注入了AnnotationMethodHandlerAdapter做用是对有RequestMapping注解的控制器进行HTTP路径、HTTP方法和请求参数解析.

项目结构

ajaxJson

项目源码已上传至 github ajaxJson

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