Spring+Mybatis整合开发（Mapper接口方式开发）实现简单的增删改查

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1、创建数据库并插入几条数据

CREATE TABLE `t_user` (`id`  int NOT NULL AUTO_INCREMENT,`username`  varchar(255) NULL ,`jobs`  varchar(255) NULL ,`phone`  varchar(255) NULL ,PRIMARY KEY (`id`));

2、创建db.properties文件
maxTotal：最大连接数，maxIdle：最大空闲连接数，initialSize：初始化连接数

jdbc.driver=com.mysql.jdbc.Driverjdbc.url=jdbc:mysql://localhost:3306/db_mybatisjdbc.username=rootjdbc.password=rootjdbc.maxTotal=30jdbc.maxIdle=10jdbc.initialSize=5

3、创建applicationContext.xml配置文件

<?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:aop="http://www.springframework.org/schema/aop"        xmlns:tx="http://www.springframework.org/schema/tx"        xmlns:context="http://www.springframework.org/schema/context"        xsi:schemaLocation="http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans-4.3.xsd        http://www.springframework.org/schema/tx        http://www.springframework.org/schema/tx/spring-tx-4.3.xsd        http://www.springframework.org/schema/context        http://www.springframework.org/schema/context/spring-context-4.3.xsd        http://www.springframework.org/schema/aop        http://www.springframework.org/schema/aop/spring-aop-4.3.xsd">        <!-- 读取db.properties -->        <context:property-placeholder location="classpath:db.properties" />        <!-- 配置数据源 -->        <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">        <!-- 数据库驱动 -->        <property name="driverClassName" value="${jdbc.driver}"  />        <!-- 连接数据库的url -->        <property name="url" value="${jdbc.url}" />        <!-- 连接数据库的用户名 -->        <property name="username" value="${jdbc.username}" />        <!-- 连接数据库的密码 -->        <property name="password" value="${jdbc.password}" />        <!-- 最大连接数 -->        <property name="maxTotal" value="${jdbc.maxTotal}" />        <!-- 最大闲置连接 -->        <property name="maxIdle" value="${jdbc.maxIdle}" />        <!-- 初始化连接数 -->        <property  name="initialSize" value="${jdbc.initialSize}" />        </bean>        <!-- 事务管理器，依赖于数据源 -->        <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">        <property name="dataSource" ref="dataSource" />        </bean>        <!-- 注册事务管理器驱动，开启事务注解 -->        <tx:annotation-driven  transaction-manager="transactionManager"  />        <!-- 配置mybatis工厂 -->        <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">        <!-- 注入数据源 -->        <property name="dataSource" ref="dataSource" />        <!-- 指定核心配置文件位置 -->        <property name="configLocation" value="classpath:mybatis-config.xml" />        </bean>         <!-- 实例化Dao -->        <bean id="userDao" class="com.ssm.dao.impl.UserDaoImpl">        <property name="sqlSessionFactory" ref="sqlSessionFactory" />        </bean>        <!-- mapper代理开发（基于MapperFactoryBean） -->        <bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">        <property name="mapperInterface" value="com.ssm.mapper.UserMapper" />        <property name="sqlSessionFactory" ref="sqlSessionFactory" />        </bean>                  <!-- mapper代理开发（基于MapperScannerConfigurer） -->          <!--          <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">         <property name="basePackage" value="com.ssm.mapper" />         </bean>       -->        </beans>

3、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><!-- 配置别名 --><typeAliases><package name="com.ssm.po" /></typeAliases><!-- 配置mapper的位置 --><mappers><mapper resource="com/ssm/mapper/UserMapper.xml" /></mappers></configuration>

4、在com.ssm.po包中创建User

package com.ssm.po;public class User {private Integer id;private String username;private String jobs;private String phone;public Integer getId() {return id;}public String getUsername() {return username;}public String getJobs() {return jobs;}public String getPhone() {return phone;}public void setId(Integer id) {this.id = id;}public void setUsername(String username) {this.username = username;}public void setJobs(String jobs) {this.jobs = jobs;}public void setPhone(String phone) {this.phone = phone;}@Overridepublic String toString() {return "User [id=" + id + ", username=" + username + ", jobs=" + jobs + ", phone=" + phone + "]";}}

5、在com.ssm.mapper下创建UserMapper接口及对应的映射文件（名字要相同）

package com.ssm.mapper;import com.ssm.po.User;public interface UserMapper {//查找public User findUserById(Integer id);//添加public int insertUser(User user);//更新public int updateUserById(User user);//删除public int deleteUser(Integer id);}

UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.ssm.mapper.UserMapper"><!-- 通过编号获取信息 --><select id="findUserById" parameterType="Integer" resultType="com.ssm.po.User">select * from t_user where id=#{id}</select><!-- 添加用户信息 --><insert id="insertUser" parameterType="com.ssm.po.User" >insert into t_user(username,jobs,phone) values(#{username},#{jobs},#{phone})</insert><!-- 更新用户信息 --><update id="updateUserById"  parameterType="com.ssm.po.User" >update t_user set username=#{username},jobs=#{jobs},phone=#{phone} where id=#{id}</update><!-- 删除用户信息 --><delete id="deleteUser" parameterType="Integer" >delete from t_user where id=#{id}</delete></mapper>

select元素要有parameterType属性以及resultType属性，因为查完返回查到的信息。
而insert、update、delete不需要resultType属性。还要注意这几个元素的parameterType属性值，传入的语句参数不同。最重要的是要保证他们的id要与你在UserMapper中写的方法名一致，最好复制粘贴。

Spring_MyBatis_Test测试类

package com.ssm.test;import org.junit.Test;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.ssm.dao.UserDao;import com.ssm.mapper.UserMapper;import com.ssm.po.User;public class Spring_MyBatis_Test {@Testpublic void findUserByIdTest(){//1、初始化spring容器，加载配置文件ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");//2、通过容器获得userDao实例UserDao userDao=(UserDao)applicationContext.getBean("userDao");//调用UserDao接口查询方法（id为2）User user=userDao.findUserById(2);System.out.println(user.toString());}@Testpublic void findUserByIdTest2(){ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");UserMapper userMapper=(UserMapper) applicationContext.getBean("userMapper");User user=userMapper.findUserById(2);System.out.println(user);}@Testpublic void insertUserTest(){ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");UserMapper userMapper=(UserMapper) applicationContext.getBean("userMapper");User user=new User();user.setUsername("hqx2");user.setJobs("teaccher");user.setPhone("123456789");userMapper.insertUser(user);}@Testpublic void insertUserTest1(){ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");//2、通过容器获得userDao实例UserDao userDao=(UserDao)applicationContext.getBean("userDao");User user=new User();user.setUsername("hqx1");user.setJobs("teaccher");user.setPhone("123456789");userDao.insertUser(user);}@Testpublic void updateUser(){ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");UserMapper userMapper=(UserMapper) applicationContext.getBean("userMapper");User user=new User();user.setUsername("11");user.setJobs("11");user.setPhone("11");user.setId(2);userMapper.updateUserById(user);}@Testpublic void deleteUserTest(){ApplicationContext applicationContext=new ClassPathXmlApplicationContext("applicationContext.xml");UserMapper userMapper=(UserMapper) applicationContext.getBean("userMapper");userMapper.deleteUser(2);}}

通过Dao接口方式开发与Mapper接口方式开发都能够实现，读者可自行测试。
但Mapper的开发方式更加简洁，代码比其少。
以下是一些注意事项：
1、在Mapper开发时，要保证Mapper接口名与Mapper.xml映射文件名一致
2、要将Mapper.xml文件的namespace与Mapper接口类路径一致（接口与映射文件要在一个包下）
项目总体架构