mybatis入门学习

港控/mmm° 2022-08-08 05:08 180阅读 0赞

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 configuration
    PUBLIC "-//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>
    		
    		<mapper resource="cn/mybatis/domain/User.xml" />
    	</mappers>
    </configuration>

映射文件

<?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="cn.mybatis.domain.User">
    	
    	<select id="selectUserById" parameterType="string" resultType="cn.mybatis.domain.User">
    		select * from User where id = #{id}
    	</select>
    	
    	
    	<select id="selectUserByIdForMap" parameterType="string" resultType="hashmap">
    		select * from User where id = #{id}
    	</select>
    	
    	
    	<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>
    	
    	
    	<select id="selectAllUser" resultType="cn.mybatis.domain.User">
    		select * from User
    	</select>
    	
    	
    	<select id="insertUser" parameterType="cn.mybatis.domain.User">
    		insert into user (id, name, address) values (#{id}, #{name}, #{address})
    	</select>
    	
    	
    	<select id="deleteUserById" parameterType="string">
    		delete from user where id = #{id}
    	</select>
    	
    	
    	<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
    	 */
    	@Test
    	public 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
    	 */
    	@Test
    	public 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
    	@Test
    	public void deleteUserById() throws Exception {
    		SqlSession session = getSession();
    		session.delete("cn.mybatis.domain.User.deleteUserById", "002");
    		session.commit();
    	}
    	
    	//更新
    	@Test
    	public 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
    	@Test
    	public 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
    	@Test
    	public 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
    	@Test
    	public 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，