Spring boot入门（二）：Spring boot集成MySql,Mybatis和PageHelper插件

时间  2019-11-07
标签 spring boot 入门 集成 mysql mybatis pagehelper 插件 栏目 Spring 繁體版
原文   原文链接

上一篇文章，写了如何搭建一个简单的Spring boot项目，本篇是接着上一篇文章写得：Spring boot入门：快速搭建Spring boot项目（一），主要是spring boot集成mybatis和pagehelpercss

关于mybatis和pagehelper的介绍，能够自行博客，网上不少相似的博客，这里，我直接上代码和项目搭建教程。html

1.配置文件：

在配置文件application.yml中配置MySql数据库链接池和Mybatis扫描包以及PageHelper分页插件前端

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.tswc.edu.entity

mapper:
  mappers:
  - com.tswc.edu.util.MyMapper
  not-empty: false
  identity: MYSQL
  #identity: SQLSERVER

pagehelper:
  helperDialect: MYSQL
  reasonable: true
  supportMethodsArguments: true
  params: count=countSql

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driverClassName: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/edu?useUnicode=true&characterEncoding=utf8
    username: root
    password: 123456
    initialSize: 1
    minIdle: 3
    maxActive: 20
    # 配置获取链接等待超时的时间
    maxWait: 60000
    # 配置间隔多久才进行一次检测，检测须要关闭的空闲链接，单位是毫秒
    timeBetweenEvictionRunsMillis: 60000
    # 配置一个链接在池中最小生存的时间，单位是毫秒
    minEvictableIdleTimeMillis: 30000
    validationQuery: select 'x'
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    # 打开PSCache，而且指定每一个链接上PSCache的大小
    poolPreparedStatements: true
    maxPoolPreparedStatementPerConnectionSize: 20
    # 配置监控统计拦截的filters，去掉后监控界面sql没法统计，'wall'用于防火墙
    filters: stat,wall,slf4j
    # 经过connectProperties属性来打开mergeSql功能；慢SQL记录
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
    # 合并多个DruidDataSource的监控数据
    #useGlobalDataSourceStat: true
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同时，须要在pom.xml中添加相应的jar包依赖,若是存在jar包没法下载，能够手动下载，而后放到相应的jar包文件夹中java

  • 这里面须要注意Spring boot和mybatis的jar包之间的版本，sping boot2+要求高版本，eg：spring boot2+不能识别pagehelper1.2如下的版本
<!--mybatis -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.4</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <!--druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.28</version>
        </dependency>

        <!--mapper-->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.1.0</version>
        </dependency>
        <!--pagehelper,Spring boot2.0+只能设备pagehelper1.2+-->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.5</version>
        </dependency>
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2.代码部分

(1).更新入口主文件，主要增长了一些注解，mysql

此处须要注意@MapperSca的引用，这里有2个可引用的包，分别是tk.mybatis.spring.annotation.MapperScan和org.mybatis.spring.annotation.MapperScan;git

tk.mybatis.spring.annotation.MapperScan：为mubatis带的mapper扫描文件，org.mybatis.spring.annotation.MapperScan为spring自带的扫描文件，在低版本的mybatis上，2个包能够随意使用，可是Spring boot2+后，增长了一些特性（建议阅读spring boot2+的底层代码，加深理解），致使只能使用高版本的mtbatis，同时spring自带的MapperScan也没法使用，因此使用sping boot2+后，须要引用高版本的mybatis，同时这里只能使用mybatis的MapperScan的扫描包；spring在后期更新中，应该也会使其可以用于boot中github

@ServletComponentScan
@MapperScan(basePackages = "com.tswc.edu.mapper")
@SpringBootApplication
public class EduApplication {

    public static void main(String[] args) {
        SpringApplication.run(EduApplication.class, args);
    }

}
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若是在项目正常，启动，可是在使用mybatis时，报此类错误：web

后台错误：没法获取实体类对应的表名!spring

2018-12-14 20:09:25.967 ERROR 29024 --- [nio-8085-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is tk.mybatis.mapper.MapperException: 没法获取实体类com.tswc.edu.entity.Index对应的表名!] with root caus 2 
tk.mybatis.mapper.MapperException: 没法获取实体类com.tswc.edu.entity.Index对应的表名!
    at tk.mybatis.mapper.mapperhelper.EntityHelper.getEntityTable(EntityHelper.java:69) ~[mapper-core-1.1.0.jar:na]
    at tk.mybatis.mapper.entity.Example.<init>(Example.java:103) ~[mapper-core-1.1.0.jar:na]
    at tk.mybatis.mapper.entity.Example.<init>(Example.java:88) ~[mapper-core-1.1.0.jar:na]
    at tk.mybatis.mapper.entity.Example.<init>(Example.java:78) ~[mapper-core-1.1.0.jar:na]
    at com.tswc.edu.service.IndexService.getList(IndexService.java:33) ~[classes/:na]
    at com.tswc.edu.controller.IndexController.list(IndexController.java:35) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.3.RELEASE.jar:5.1.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:791) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_151]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.13.jar:9.0.13]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_151]
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前端错误是500sql

Whitelabel Error Page
 This application has no explicit mapping for /error, so you are seeing this as a fallback.
 
 Fri Dec 14 20:09:25 CST 2018
 There was an unexpected error (type=Internal Server Error, status=500).
 ???????com.tswc.edu.entity.Index?????!
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那么，就是Mapper扫描包使用有误

(2).通用接口mapper：此接口不能被扫描到，不然会报错，能够在application.yml中，排除此包的扫描

public interface MyMapper<T> extends Mapper<T> {
     //TODO
     //FIXME 特别注意，该接口不能被扫描到，不然会出错
 }
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(3).后台代码，控制村层>服务层>接口

@Controller
public class IndexController {
    @Autowired
    private IndexService indexService;

    @RequestMapping(value = "/index")
    public void list(ModelMap modelMap) {
        List<Index> list = indexService.getList();
        modelMap.put("list", list);
    }
}
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@Service
public class IndexService {
    @Autowired
    private IndexMapper indexMapper;

    public List<Index> getList() {
        Example example = new Example(Index.class);
        example.setTableName("index_test");
        Criteria criteria = example.createCriteria();
        criteria.andEqualTo("age", 20);
        return indexMapper.selectByExample(example);
    }
}
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public interface IndexMapper extends MyMapper<Index> {
 }
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@Table(name = "index_test")
public class Index implements Serializable, IDynamicTableName {
    private static final long serialVersionUID = -8709793124943394842L;

    @Transient
    private String dynamicTableName;
    private String name;
    private Integer age;

    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;
    }

    @Override
    public String getDynamicTableName() {
        return null;
    }
}
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最后一个类为实体类，建议在创建实体类的时候，统一加上@Table的注解，方便后期Mybatis的使用，同时也提升了代码的规范性。固然，若是咱们使用Mybatis的代码生成器，那么均会自动加上注解（代码生成器在后期的博客中会讲到）

(4).前端ftl代码

<!DOCTYPE html>
<html>
<head lang="en">
    <title>Spring Boot Demo - FreeMarker</title>
    <link href="/css/index.css" rel="stylesheet" />
</head>
<body>
    <table>
        <#list list as user>
        <tr>
            <td>第${user_index+1}个用户</td>
            <td>用户名：${user.name}</td>
            <td>年  龄: ${user.age}</td>
        </tr>
        </#list>
    </table>
</body>
</html>
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(5).添加mybatis的空配置文件，因为spring boot中，数据库是经过配置文件的形式，因此此文件是空的，可是没有此文件，mybatis就没法经过；固然，也能够经过在此文件做用配置数据库链接池的方式链接数据（已过期）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD SQL MAP Config 3.1//EN"
    "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
  <settings>
    <setting name="callSettersOnNulls" value="true"/>
  </settings>
</configuration>
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(6).数据库以下：添加了几条测试数据：

(7).启动项目，并访问http://localhost:8085/index，结果以下：

最终，项目代码的机构，以下：

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