idea创建SSM项目（Spring+SpringMVC+MyBatis）

项目创建
创建数据库
自动生成mapper
先做一个简单的测试
以下配置可参考博客https://blog.csdn.net/weixin_45301250/article/details/121298472(我已省略)

本人小白一个，如果有错误的地方，欢迎指正

项目创建

点击next

选择本地配置好的maven（maven配置可查看相关博客），点击finish

复制粘贴 dependencies标签内的内容就好

<?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>org.example</groupId><artifactId>mybatis_test</artifactId><version>1.0-SNAPSHOT</version><packaging>war</packaging><name>mybatis_test Maven Webapp</name><!-- FIXME change it to the project's website --><url>http://www.example.com</url><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.11</version><scope>test</scope></dependency><!--Hutool--><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>5.6.5</version></dependency><!--LomBok--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.16.18</version></dependency><!--  Spring+SpringMVC --><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>4.3.8.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>4.3.8.RELEASE</version><exclusions><!-- Exclude Commons Logging in favor of SLF4j --><exclusion><groupId>commons-logging</groupId><artifactId>commons-logging</artifactId></exclusion></exclusions></dependency><!-- 事务管理 --><dependency><groupId>org.springframework</groupId><artifactId>spring-tx</artifactId><version>4.3.8.RELEASE</version></dependency><!-- Spring的jdbc模块 --><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>4.3.8.RELEASE</version></dependency><!-- 做jdbc的连接管理 --><dependency><groupId>org.apache.commons</groupId><artifactId>commons-dbcp2</artifactId><version>2.1.1</version></dependency><!-- jsp-api --><dependency><groupId>javax.servlet</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId><version>2.5</version><scope>provided</scope></dependency><dependency><groupId>javax.servlet.jsp</groupId><artifactId>jsp-api</artifactId><version>2.2</version><scope>provided</scope></dependency><!-- MyBatis --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.4.1</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.16</version></dependency><dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper</artifactId><version>5.1.2</version></dependency><!-- MyBatis-Spring连接包 --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>1.3.1</version></dependency><!-- jackson --><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-core</artifactId><version>2.8.8</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.8.8</version></dependency><!-- 日志管理 --><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>1.7.5</version><scope>compile</scope></dependency><dependency><groupId>ch.qos.logback</groupId><artifactId>logback-classic</artifactId><version>1.0.13</version><scope>runtime</scope></dependency></dependencies>
</project>

配置好之后点一下右上角的按钮，开始下载相关的jar包

右键src，选择new，directory

创建这四个文件夹（如果不需要测试的话，也可以只创建main下的两个）

那现在这就是我们暂时的目录结构

创建数据库

/* 创建mybatis数据库 */
create database mybatis;
use mybatis;/* 创建用户表 */
create table user
(id       int auto_increment,username varchar(255) not null,password varchar(255) not null,constraint primary key (id)
);/* 创建角色表 */
create table role(id int auto_increment,name varchar(255) not null ,constraint primary key (id)
);/* 创建用户-角色详情表 */
create table userinfo(id int auto_increment,user_id int not null ,role_id int not null ,constraint primary key (id)
);

解释一下这三个表之间的关系

这里我并没有设置外键约束，其实设置一下也没问题。
有人可能不太理解role表的含义，这里我解释一下，类似权限的划分。
是游客用户？还是普通用户？或者是VIP用户？

/* 插入几个数据 */insert into user (username, password) values ('abc','123');
insert into user (username, password) values ('admin','123456');insert into role (name) values ('tourist');
insert into role (name) values ('common');insert into userinfo (user_id, role_id) values (1,1);
insert into userinfo (user_id, role_id) values (1,1);
insert into userinfo (user_id, role_id) values (2,1);

自动生成mapper

这里需要下载几个jar包
链接：https://pan.baidu.com/s/1KZyUXrCZ6DU0V2frbk8aew?pwd=lej6
提取码：lej6

改好xml之后，复制mybatis自动生成命令，输入cmd+回车
（也可以用cmd cd到当前auto目录，也可以选中auto+按住shift+右键选择cmd/powershell打开）

输入命令后回车，看到successfully表示生成成功了
如果有其他情况，没有successfully，可能是generatorConfig.xml出错了，找不到数据库/表

直接将生成的com.XXX.domain/mapper复制粘贴到java下

稍微修改一下目录结构（在resources下新建mapper文件夹，将xml文件全部移到mapper文件夹内）

这里三个实体类自动生成了get和set方法，但其实可以用pom.xml里下载好的lombok插件来配置

public class Role {private Integer id;private String name;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 == null ? null : name.trim();}
}import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@AllArgsConstructor
@NoArgsConstructor
public class Role {private Integer id;private String name;
}/* 感兴趣的可以去搜一下lombok的注解@Data、@AllArgsConstructor、@NoArgsConstructor这里我们就这么配置*/// user
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {private Integer id;private String username;private String password;// 注意：这里我添加了一个属性private List<UserInfo> userInfoList;
}// role
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Role {private Integer id;private String name;// 注意：这里我添加了一个属性private List<UserInfo> userInfoList;
}// userinfo
@Data
@AllArgsConstructor
@NoArgsConstructor
public class UserInfo {private Integer id;private Integer userId;private Integer roleId;
}

先做一个简单的测试

我们可以上网找一下返回结果工具类（下面也提供了一个不完全的）
在com.XXX下新建一个util文件夹（idea右键，new，directory//也可以直接在外面项目文件夹新建）

package com.twh.util;import java.io.Serializable;public class Result<T> implements Serializable {//返回的结果集类private Integer code;//服务器响应的状态   不是http状态private String msg;//备注private T data;//返回的数据public Result() {}public Result(Integer code, String msg, T data) {this.code = code;this.msg = msg;this.data = data;}public Integer getCode() {return code;}public Result setCode(Integer code) {this.code = code;return this;}public String getMsg() {return msg;}public Result setMsg(String msg) {this.msg = msg;return this;}public T getData() {return data;}public Result setData(T data) {this.data = data;return this;}@Overridepublic String toString() {return "Result{" +"code=" + code +", msg='" + msg + '\'' +", data=" + data +'}';}public Result setCode(com.twh.util.ResultEnum resultEnum) {this.code = resultEnum.code;return this;}
}//--------------------------------------------package com.twh.util;public enum  ResultEnum {//枚举类/*** 成功*/SUCCESS(200),/*** 失败*/FAIL(400),/*** 接口不存在*/NOT_FOUND(404),/*** 服务器内部错误*/INTERNAL_SERVER_ERROR(500);public int code;ResultEnum(int code) {this.code = code;}
}//-----------------------------------------package com.twh.util;import com.twh.util.Result;
import com.twh.util.ResultEnum;public class ResultUtil {public static <T> Result<T>  defineSuccess(Integer code, T data) {Result result = new Result<>();return result.setCode(code).setData(data);}public static <T> Result<T> success(T data) {Result result = new Result();result.setCode(ResultEnum.SUCCESS).setData(data);return result;}public static <T> Result<T> fail(String msg) {Result result = new Result();result.setCode(ResultEnum.FAIL).setMsg(msg);return result;}public static <T> Result<T> defineFail(int code, String msg){Result result = new Result();result.setCode(code).setMsg(msg);return result;}public static <T> Result<T> define(int code, String msg, T data){Result result = new Result();result.setCode(code).setMsg(msg).setData(data);return result;}
}

这里遇到了奇奇怪怪的报错，设置有点问题

设置为8，点击OK，错误消除了

新建impl

新建controller

以下配置可参考博客https://blog.csdn.net/weixin_45301250/article/details/121298472(我已省略)

<!--  mybatis-config.xml    复制粘贴，覆盖掉原本的内容 -->
<!-- 如果你的命名和我不一样，那么下面有些文件名字得改改 --><?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration  PUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><settings><!-- mybatis通过日志来打印sql语句 --><setting name="logImpl" value="STDOUT_LOGGING"/><setting name="useGeneratedKeys" value="true"/></settings><!--设置别名--><typeAliases><package name="com.twh.domain"/></typeAliases><plugins><plugin interceptor="com.github.pagehelper.PageInterceptor"/></plugins><!--绑定mapper映射文件--><mappers><mapper resource="mapper/UserMapper.xml"/><mapper resource="mapper/UserInfoMapper.xml"/><mapper resource="mapper/RoleMapper.xml"/></mappers></configuration>

那么，基本配置到此结束，开始编写代码

// usermapper.java
public interface UserMapper {int deleteByPrimaryKey(Integer id);int insert(User row);int insertSelective(User row);User selectByPrimaryKey(Integer id);int updateByPrimaryKeySelective(User row);int updateByPrimaryKey(User row);List<User> getAllUsers();// 根据账号查找用户User selectByUsername(@Param("username") String username);// 根据user id查找对应的多个userinfoUser selectUserInfoByUsername(@Param("username") String username);
}

<!-- usermapper.xml --><select id="getAllUsers" resultType="User">select id,username,password from user;</select><select id="selectByUsername" parameterType="java.lang.String" resultType="User">select id,username,password from user where username=#{username};</select><select id="selectUserInfoByUsername" parameterType="java.lang.String" resultMap="UserInfoByUserId">select u.id,username,password,info.id,info.user_id,info.role_id from user u join userinfo info where info.user_id in (select u.id from user s where u.username=#{username});</select><resultMap id="UserInfoByUserId" type="User"><result property="id" column="id"/><result property="username" column="username"/><result property="password" column="password"/><collection property="userInfoList" ofType="UserInfo"><result property="id" column="id"/><result property="userId" column="user_id"/><result property="roleId" column="role_id"/></collection></resultMap>
</mapper>

// mytest.java
public class MyTest {// 获取全部users@Testpublic void test1(){SqlSession sqlSession = MybatisUtils.getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<User> users = mapper.getAllUsers();for (User user : users) {System.out.println(user);}sqlSession.close();}// 获取指定账号的user@Testpublic void test2(){SqlSession sqlSession = MybatisUtils.getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = mapper.selectByUsername("admin");System.out.println(user);sqlSession.close();}// 获取指定user账号的userinfo@Testpublic void test3(){SqlSession sqlSession = MybatisUtils.getSqlSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = mapper.selectUserInfoByUsername("abc");System.out.println(user);sqlSession.close();}
}

这里可以查到user id对应的userinfo 的内容(直接在MyTest下test1、test2、test3处点击运行即可)

这是运行test1（test2、test3就分别在他们的方法内右键运行）
暂时MyBatis相关配置已经成功了
更改一些配置文件，删除了一些配置

接下来配置其他的

在resources下再额外新建两个xml文件（springmvc.xml applicationContext.xml）

<!-- applicationContext.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:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"><context:component-scan base-package="com.twh.*"><context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/></context:component-scan><!-- 1.管理数据库连接，使用数据库连接池的方式 --><bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource"><property name="driverClassName" value="com.mysql.jdbc.Driver"></property><property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&amp;characterEncoding=utf8"></property><property name="username" value="root"></property><property name="password" value="123456"></property></bean><!-- 2.获得sqlsessionFactory --><bean id="sqlsessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"><property name="configLocation" value="classpath:mybatis-config.xml"></property><property name="dataSource" ref="dataSource"></property><property name="mapperLocations" value="classpath:mapper/*.xml"></property></bean><!-- 3.扫描mapper.xml文件，获得mapper对象 --><bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"><property name="basePackage" value="com.twh.mapper"></property><property name="sqlSessionFactoryBeanName" value="sqlsessionFactory"></property></bean><!-- 4.管理事务  DML操作：增删改 --><bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"><property name="dataSource" ref="dataSource"></property></bean><tx:annotation-driven transaction-manager="txManager" />
</beans>

<!-- 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:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xmlns:mvc="http://www.springframework.org/schema/mvc"xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsdhttp://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"><mvc:annotation-driven/><mvc:default-servlet-handler/><context:component-scan base-package="com.twh.controller"><context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/></context:component-scan></beans>

这个xml是原本就有得，现在需要进行一些配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"id="WebApp_ID" version="3.0"><display-name>Archetype Created Web Application</display-name><listener><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener><context-param><param-name>contextConfigLocation</param-name><param-value>classpath:applicationContext.xml</param-value></context-param><servlet><servlet-name>springmvc</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><!-- 自定义springmvc的配置文件路径 --><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:springmvc.xml</param-value></init-param><load-on-startup>1</load-on-startup></servlet><servlet-mapping><servlet-name>springmvc</servlet-name><url-pattern>/</url-pattern></servlet-mapping><filter><!-- post/put --><filter-name>CharacterEncodingFilter</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></filter><filter-mapping><filter-name>CharacterEncodingFilter</filter-name><url-pattern>/*</url-pattern></filter-mapping></web-app>

这里的配置与applicationContext.xml的配置重复了，注释掉，不然会报错

实现登录功能

// userservicepublic interface UserService {Object login(User user);
}//---------------------------------------------------------------// userserviceImpl
@Service
public class UserServiceImpl implements UserService {@Autowiredprivate UserMapper userMapper;@Overridepublic Object login(User user) {String username=user.getUsername();String password=user.getPassword();// 需要导入hutool工具类才能这么写if(StrUtil.hasEmpty(username,password)){return ResultUtil.fail("账号或密码为空");}// 否则得这样写// if(username==null||username.equals("")||password==null||password.equals(""))User u=userMapper.selectByUsername(username);if(u==null){return ResultUtil.fail("账号未注册");}else {if(u.getPassword().equals(password)){return ResultUtil.success("登陆成功");}else {return ResultUtil.fail("密码错误");}}}
}//---------------------------------------------------------------// usercontroller  这里写的有点low
// 暂时先这么写 编写一个html登录页面就可以传账号、密码进来了 后面会改用ajax来写@Controller
@RequestMapping("/user")
public class UserController {@Autowiredprivate UserService userService;@RequestMapping(value = "/login", method = RequestMethod.POST)@ResponseBodypublic Object login(String username,String password) {User user=new User();user.setUsername(username);user.setPassword(password);return userService.login(user);}
}

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<form action="user/login" method="post"><label>账号:</label><input type="text" name="username" class="username" placeholder="账号"/><br><label>密码:</label><input type="password" name="password" class="password" placeholder="密码"/><br><input type="submit" value="登录"/>
</form>
</body>
</html>

删除后面的内容

开始运行

输入账号密码，登陆成功
这里我用了插件，json数据看起来会好看点（可以在网上搜浏览器json插件）

去bootstrap官网下了一个免费模板
链接：https://pan.baidu.com/s/1aLX8iJBdeeE2nQEXnVjBfw?pwd=94ky
提取码：94ky

这是登录页面

<script src="js/jquery.min.js"></script>
<!-- 这里在登录页面加了一个点击事件,只用复制粘贴 οnclick="login()"到页面该位置即可 -->
<button type="button" class="btn btn-block btn-primary" onclick="login()">Sign in</button>
<script>function login() {let username = $("#input-email").val();let password = $("#input-password").val();let user = {"username": username,"password": password};$.ajax({url: "user/login",type: "post",dataType: "json",contentType:"application/json",data: JSON.stringify(user),success: function (message) {console.log(message);},error: function (message) {console.log("失败");}})}
</script>
<!-- 打包一个user对象发给后端usercontrolller -->

// usercontroller改为下面的代码即可
@Controller
@RequestMapping("/user")
public class UserController {@Autowiredprivate UserService userService;@RequestMapping(value = "/login", method = RequestMethod.POST)@ResponseBodypublic Object login(@RequestBody User user) {return userService.login(user);}
}

打开F12，输入账号密码登录

其他业务方法也是类似写，发送ajax请求，通过对后端返回得code来进行判断是否成功，并进行相应的处理

全代码
链接：https://pan.baidu.com/s/1TvGHH6BISzQCYIJWIJwgxg?pwd=kqp5
提取码：kqp5