不灭的火

先参考文章：【Spring MVC】使用IDEA创建Spring MVC的Maven项目 ，创建 Spring MVC 项目。

MyBatis最大的特点是：只需要写好 针对实体类映射数据库表的接口，不需要写接口的实现，MyBatis动态完成接口的实现。

MyBatis完成Java实体类和数据库表的ORM映射，主要有两种方式，一种是基于注解的；另外一种是基于XXXMaper.xml，用xml文件装配SQL，MyBatis动态实现接口的Impl，自动加载到Spring IoC容器，Controller在需要时即可@Autowired，本教程就是用第二种方式，实现最简单的User实体类与数据库表的映射，完成增删改查。

1、在Maven中添加“MySQL操作 相关依赖”：

<!--++++++++++++++++++++++++++++++++++++++++++++++++++++-->
<!-- MySQL操作 相关依赖 -->
<!--++++++++++++++++++++++++++++++++++++++++++++++++++++-->
<!-- MySQL JDBC驱动 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.23</version>
</dependency>
<!-- 数据库连接池 -->
<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.5.5</version>
</dependency>
<!-- DAO框架：MyBatis -->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.6</version>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis-spring</artifactId>
    <version>2.0.6</version>
</dependency>

2、在 applicationContext.xml 中加入内容：

<!--++++++++++++++++++++++++++++++++++++++++++++++++++++-->
<!-- MyBatis配置 -->
<!--++++++++++++++++++++++++++++++++++++++++++++++++++++-->
<context:property-placeholder location="classpath:jdbc.properties"/>
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"
      p:driverClass="${driver}"
      p:jdbcUrl="${url}"
      p:user="${username}"
      p:password="${password}"
      p:idleConnectionTestPeriod="${idleConnectionTestPeriod}"
      p:maxIdleTime="${maxIdleTime}"
      p:acquireIncrement="${acquireIncrement}"
      p:initialPoolSize="${initialPoolSize}"
      p:maxPoolSize="${maxPoolSize}"
      p:minPoolSize="${minPoolSize}"
      p:autoCommitOnClose="${autoCommitOnClose}"
      p:checkoutTimeout="${checkoutTimeout}"
      p:acquireRetryAttempts="${acquireRetryAttempts}"
      p:preferredTestQuery="SELECT 1"
      p:maxConnectionAge="3000"/>

<!-- MyBatis文件配置，扫描所有mapper文件 -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="configLocation" value="classpath:mybatis-config.xml"/>
    <property name="typeAliasesPackage" value="com.jianbao.entity"/>
    <property name="mapperLocations" value="classpath:mapper/*.xml"/>
</bean>
<!-- Spring与MyBatis整合配置，扫描所有DAO，指定的映射器类是接口，
    接口方法可以用注解来指定SQL语句，但是MyBatis的映射器也可以用XML文件 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"
      p:basePackage="com.jianbao.dao"
      p:sqlSessionFactoryBeanName="sqlSessionFactory"/>

<!-- 使用@Transactional进行声明式事务管理需要声明下面这行 -->
<tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true" />
<!-- 事务管理 -->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
    <property name="rollbackOnCommitFailure" value="true"/>
</bean>

3、新建文件：/src/main/resources/jdbc.properties

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/java_web?useUnicode=true&useSSL=false&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&autoReconnect=true&serverTimezone=Asia/Shanghai
username=root
password=123456

idleConnectionTestPeriod=60
maxIdleTime=240
acquireIncrement=5
initialPoolSize=10
maxPoolSize=30
minPoolSize=10
autoCommitOnClose=false
checkoutTimeout=1000
acquireRetryAttempts=2

4、新建文件：/src/main/resources/mybatis-config.xml

<?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>
    <!-- mybatis全局设置 -->
    <settings>
        <!--使用数据库自增id-->
        <setting name="useGeneratedKeys" value="true"/>
        <setting name="useColumnLabel" value="true"/>

        <!-- 开启驼峰命名规范-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

5、创建实体文件：/src/main/java/com/jianbao/entity/User.java

package com.jianbao.entity;

public class User {
    private Integer id;
    private String user_name;
    private String password;
    private String email;
    private String add_time;

    public Integer getId() {
        return id;
    }

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

    public String getUserName() {
        return user_name;
    }

    public void setUserName(String userName) {
        this.user_name = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

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

    public String getAddTime() {
        return add_time;
    }

    public void setAddTime(String addTime) {
        this.add_time = addTime;
    }
    
    public String toString() {
        return "User{" +
            "id=" + id +
            ", user_name=" + user_name +
            ", password=" + password +
            "}";
    }
}

6、新建 Mapper 接口文件：/src/main/java/com/jianbao/dao/UserDao.java

package com.jianbao.dao;

import com.jianbao.entity.User;

import java.util.List;

/**
 * DAO接口，MyBatis动态完成Impl(接口实现)
 */
public interface UserDao {
    Integer addUser(User u);
    Integer deleteById(Integer id);
    User findByUserName(String userName);
    User findById(Integer id);
    List<User> getUserList();
}

7、新建 Mapper 配置文件：/src/main/resources/mapper/userDao.xml

<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.jianbao.dao.UserDao">
    <insert id="addUser" parameterType="com.jianbao.entity.User">
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
            SELECT last_insert_id()
        </selectKey>
        INSERT INTO user(user_name, password, email) VALUE (#{userName}, #{password}, #{email})
    </insert>
    <delete id="deleteById" parameterType="java.lang.Integer">
        DELETE FROM user WHERE id=#{id}
    </delete>
    <select id="findById" parameterType="java.lang.Integer" resultType="com.jianbao.entity.User">
        SELECT * FROM user WHERE id=#{id}
    </select>
    <select id="findByUserName" parameterType="java.lang.String"  resultType="com.jianbao.entity.User">
        SELECT * FROM user WHERE user_name=#{userName}
    </select>
    <select id="getUserList" resultType="com.jianbao.entity.User">
        SELECT * FROM user
    </select>

</mapper>

8、新建控制器文件：/src/main/java/com/jianbao/controller/UserController.java

package com.jianbao.controller;

import com.jianbao.dao.UserDao;
import com.jianbao.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
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.bind.annotation.ResponseBody;

import java.util.List;

@Controller
@RequestMapping("/user")
public class UserController {
    @Autowired(required = true)
    private UserDao userDao;

    @RequestMapping(value = "/index", method = RequestMethod.GET)
    @ResponseBody
    public String index() {
        User user = userDao.findByUserName("wjb");
        System.out.println(user);
        return "ok";
    }

    @RequestMapping(value = "list", method = RequestMethod.GET)
    @ResponseBody
    public String userList() {
        List<User> userList = userDao.getUserList();
        System.out.println(userList);
        return "ok";
    }
    
    @RequestMapping(value = "/add", method = RequestMethod.GET)
    @ResponseBody
    public String save(@RequestParam("userName") String userName,
                     @RequestParam(value = "password", defaultValue = "123456") String password,
                     @RequestParam(value = "email", defaultValue = "phpjava8642@163.com") String email) {

        // 添加用户
        User user = new User();
        user.setUserName(userName);
        user.setPassword(password);
        user.setEmail(email);
        userDao.addUser(user);
        
        User userNew = userDao.findById(user.getId());
        System.out.println(userNew);
        
        return "ok";
    }

    @RequestMapping(value = "/delete", method = RequestMethod.GET)
    @ResponseBody
    public String delete(@RequestParam("id") Integer id) {
        userDao.deleteById(id);
        return "ok";
    }
}

9、项目目录结构截图

参考：

IDEA SpringMVC 集成 mybatis 教程

[手把手教程][JavaWeb]优雅的SpringMvc+Mybatis整合之路