mybatis入门学习

首先mybatis有一个总的配置文件，和映射文件,可以在下载的pdf介绍中参考写法

下面演示一个使用mybatis的CUDR操作

总配置文件sqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><environments default="development"><environment id="development"><transactionManager type="JDBC" /><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver" /><property name="url" value="jdbc:mysql:///mybatis" /><property name="username" value="root" /><property name="password" value="123" /></dataSource></environment></environments><mappers><!-- 映射文件 --><mapper resource="cn/mybatis/domain/User.xml" /></mappers></configuration>

映射文件

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="cn.mybatis.domain.User"><!-- namespace保证唯一 --><!-- 根据id查询, parameterType参数类型, resultType结果类型--><select id="selectUserById" parameterType="string" resultType="cn.mybatis.domain.User">select * from User where id = #{id}</select><!-- 查询返回为map --><select id="selectUserByIdForMap" parameterType="string" resultType="hashmap">select * from User where id = #{id}</select><!-- 动态sql where可以代替1=1--><select id="selectUserByCondition" parameterType="cn.mybatis.domain.User" resultType="cn.mybatis.domain.User">select * from User where<where><if test="id != null">id = #{id}</if><if test="name != null">and name = #{name}</if><if test="address != null">and address = #{address}</if></where></select><!-- 查询所有 --><select id="selectAllUser" resultType="cn.mybatis.domain.User">select * from User</select><!-- 插入 --><select id="insertUser" parameterType="cn.mybatis.domain.User">insert into user (id, name, address) values (#{id}, #{name}, #{address})</select><!-- 删除 --><select id="deleteUserById" parameterType="string">delete from user where id = #{id}</select><!-- 更新--><select id="updateUserById" parameterType="cn.mybatis.domain.User">update user set name = #{name}, address = #{address} where id = #{id}</select></mapper>

然后是测试类

package cn.mybatis.test;import java.io.InputStream;import java.util.List;import java.util.Map;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.Test;import cn.mybatis.domain.User;public class MybatisTest {public SqlSession getSession() throws Exception {String resource = "sqlMapConfig.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(inputStream);SqlSession session = ssf.openSession();return session;}/** * 查询User * @throws Exception */@Testpublic void selectOne() throws Exception {String resource = "sqlMapConfig.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(inputStream);SqlSession session = ssf.openSession();User user = session.selectOne("cn.mybatis.domain.User.selectUserById", "001");System.out.println(user);}/** * 查询返回map类型 * @throws Exception */@Testpublic void selectUserForMap() throws Exception {SqlSession session = getSession();Map<String, String> map = session.selectOne("cn.mybatis.domain.User.selectUserByIdForMap", "001");System.out.println(map);}//删除@Testpublic void deleteUserById() throws Exception {SqlSession session = getSession();session.delete("cn.mybatis.domain.User.deleteUserById", "002");session.commit();}//更新@Testpublic void updateUserById() throws Exception {SqlSession session = getSession();User user = new User();user.setId("002");user.setName("zhaodaxia");user.setAddress("shanghai");session.delete("cn.mybatis.domain.User.updateUserById", user);session.commit();}//查询所有@Testpublic void selectList() throws Exception {String resource = "sqlMapConfig.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(inputStream);SqlSession session = ssf.openSession();List<User> userList = session.selectList("cn.mybatis.domain.User.selectAllUser");for (User user : userList) {System.out.println(user);}}//插入@Testpublic void insertUser() throws Exception {SqlSession session = getSession();User user = new User();user.setId("002");user.setName("xiaozhao");user.setAddress("shanghai");//i影响的数据库条数int i = session.insert("cn.mybatis.domain.User.insertUser", user);//影响数据库需要提交事务session.commit();System.out.println(i);}//动态sql@Testpublic void selectUserByCondition() throws Exception {SqlSession session = getSession();User user = new User();user.setName("zhaodaxia");List<User> userList = session.selectList("cn.mybatis.domain.User.selectUserByCondition", user);for (User userResult : userList) {System.out.println(userResult);}}}

当实体和数据库表明字段不一致时，可以在sql语句中使用别名，