Mybatis框架基本使用

淡淡的烟草味﹌ 2023-10-02 09:36 37阅读 0赞

## Mybatis框架基本使用 ##

## 操作 ##

### 1.引入dtd文件 -> 编写xml文件 ###

myTool\dtd\mybatis-3-config.dtd
    myTool\dtd\mybatis-3-mapper.dtd

### 2.导入依赖项(jar包) ###

mybatis-3.5.2.jar
    mysql-connector-java-5.1.46.jar

### 3.配置文件 ###

mybatis.cfg.xml	-> 核心配置 <- mybatis-3-config.dtd
    	连接池
    	注册映射
    	
    Mapper映射 -> 业务操作 <- mybatis-3-mapper.dtd
    	接口		namespace="com.uplooking.dao.DeptDO"
    	实体类		resultType="com.uplooking.pojo.DeptVO"
    	业务方法
    				<select id="find" resultType="com.uplooking.pojo.DeptVO">
    					SELECT deptno,dname,loc FROM dept LIMIT #{start},#{limit}
    				</select>

### 4.API操作 ###

sqlSession = MyBatisUtils.getSqlSession();
    DeptDO deptDO = sqlSession.getMapper(DeptDO.class);

## 概念 ##

### 1.核心类 ###

SqlSessionFactoryBuilder	-> 类		局部变量
    
    SqlSessionFactory			-> 接口		单例模式
    	DefaultSqlSessionFactory
    
    SqlSession					-> 接口		会话独立**，具有回滚提交的功能，在插入元素的时候使用**
    	DefaultSqlSession

**代码演示：**

<?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"></transactionManager>
    			<dataSource type="POOLED">
    				<property name="driver" value="com.mysql.jdbc.Driver"/>
    				<property name="url" value="jdbc:mysql://localhost:3306/mytest"/>
    				<property name="username" value="root"/>
    				<property name="password" value="root"/>
    			</dataSource>
    		</environment>
    	</environments>
    	<mappers>
    	<mapper resource="mappers/DeptDO.xml"/>
    	<mapper resource="mappers/EmpDO.xml"/>
    	</mappers>
    </configuration>

### 2.ORM -> 对象关系映射 ###

表		列
    	public class DeptVO {}
    实体类	字段	
    	@Param("id")int id
    OGNL	#{键}

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAUmVjZW50bHkg56Wd56Wd_size_20_color_FFFFFF_t_70_g_se_x_16]

**代码演示：**

<?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.uplooking.dao.DeptDO">
     	<select id="findById" resultType="com.uplooking.pojo.DeptVO">
     	SELECT deptno,dname,loc FROM dept WHERE deptno= #{id}
     	</select >
     	<select id="find" resultType="com.uplooking.pojo.DeptVO">
     	SELECT deptno,dname,loc FROM dept LIMIT #{start},#{end}
     	</select>
     	<insert id="insert" >
     	INSERT INTO dept(deptno,dname,loc) 
     	 VALUEs(#{item.deptno},#{item.dname},#{item.loc})
     	</insert>
     	<insert id="insert1" >
     	insert into dept(deptno,dname,loc) VALUEs(#{deptno},#{dname},#{loc})
     	</insert>
     	<update id="update">
     	UPDATE dept SET dname=#{dname},loc=#{loc} WHERE deptno=#{deptno};
     	</update>
    </mapper>

![在这里插入图片描述][6e4389bed3a84fb0adddbb4b5eeeacd7.png]

### 3.业务原理 -> 动态代理 ###

//会话通过动态代理产生代理对象 实现代理接口 
    //sqlSession.getMapper(type);
    //configuration.getMapper(type, this);
    //mapperRegistry.getMapper(type, sqlSession);
    //mapperProxyFactory.newInstance(sqlSession);
    //Proxy.newProxyInstance(mapperInterface.getClassLoader(), new Class[] { mapperInterface }, mapperProxy);
    //class MapperProxy<T> implements InvocationHandler
    DeptDO deptDO = sqlSession.getMapper(DeptDO.class);

**代码演示：**

package com.uplooking.test;
    
    import org.apache.ibatis.session.SqlSession;
    import org.junit.Test;
    
    import com.uplooking.dao.DeptDO;
    import com.uplooking.dao.EmpDO;
    import com.uplooking.pojo.EmpVO;
    import com.uplooking.utils.MybatisUtils;
    
    public class MyBatisTest {
    
    //	@Test
    	public void testDeptDO() {
    		SqlSession session = MybatisUtils.getSqlSession();
    		DeptDO deptDO = session.getMapper(DeptDO.class);
    		int i = 10;
    		System.out.println(deptDO.findById(10));
    		System.out.println(deptDO.find(0, 2));
    
    	}
    	@Test
    	public void testEmpDO() {
    		SqlSession session = MybatisUtils.getSqlSession();
    		EmpDO empDO = session.getMapper(EmpDO.class);
    		int i = 10;
    		System.out.println(empDO.findByid(10));
    //		System.out.println(deptDO.find(0, 2));
    		int index=1;
    		int size=5;
    		int ix= (index-1)*5;
    		System.out.println(empDO.find(ix, size));
    
    	}
    }

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[6e4389bed3a84fb0adddbb4b5eeeacd7.png]: https://img-blog.csdnimg.cn/6e4389bed3a84fb0adddbb4b5eeeacd7.png