MyBatis入门使用方式

ゞ浴缸里的玫瑰 2021-09-15 18:28 323阅读 0赞

MyBatis解决了JDBC的不便于修改，硬编码过多的缺点，是一种比较轻量级的框架

动态代理模式能简化代码的编写，只需配置一些xml文件就能动态生成代理对象来执行sql。

需要的文件：JDK、Mybatis架包（官网下载后lib全部导入）、log4日志文件（可以不用）、JDBC驱动包（网上哪都有）

关键文件：sqlMapConfig.xml（差不多是个数据库全局配置，需放到classpath下）、类+Mapper.xml（sql语句相关配置文件）、jdbc.properties（存放JDBC连接参数）

创建一个java工程如图所示：注意sqlMapConfig.xml文件一定要放到classpath下，只需将文件夹右键Sourse Folder就行

![70][]

非代理模式：在xml中配置sql并按id区分，SqlSession再跟进namespace+id来执行不同的sql

入门程序配置如下

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>
    
    	
    	<properties resource="jdbc.properties"></properties>
    	
    	
    	<typeAliases>
    		<typeAlias type="com.baidu.dept.Dept" alias="dept"/>
    	</typeAliases>
    	
    	
      	<environments default="development">
    		<environment id="development">
    			<transactionManager type="JDBC" />
    			<dataSource type="POOLED">
    				<property name="driver" value="${driver}" />
    				<property name="url" value="${url}" />
    				<property name="username" value="${username}" />
    				<property name="password" value="${password}" />
    			</dataSource>
    		</environment>
    	</environments>
    	
    	
    	<mappers>
    		
    		
    		
    		
    		<package name="com.baidu.mapper"/>
    	</mappers>
    	
    </configuration>

sql配置文件：常用的语句，增删查改...

<?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="test">
    	
    	<select id="getDeptList" resultType="dept">
    		select * from testdept
    	</select>
    	
    	
    	<select id="getDeptById" parameterType="int" resultType="dept">
    		select * from testdept where did=#{did}
    	</select>
    	<select id="getDeptById2" parameterType="int" resultType="dept" >
    		select * from testdept where did=${value}
    	</select>
    	
    	<select id="getDeptListByMohu" parameterType="String" resultType="dept">
    		select * from testdept where dname like #{dname}
    	</select>
    	<select id="getDeptListByMohu2" parameterType="String" resultType="dept">
    		select * from testdept where dname like ${value}
    	</select>
    	
    	
    	<select id="getDeptListByDept" parameterType="com.baidu.dept.Dept" resultType="dept">
    		select * from testdept where dname like #{dName}
    	</select>
    	
    	<select id="getDeptCount" resultType="int">
    		select count(did) from testdept
    	</select>
    	
    	<insert id="insertDept" parameterType="dept">
    		insert into testdept set dname=#{dName}
    	</insert>
    	<insert id="insertDept2" parameterType="dept">
    		
    		
    		<selectKey keyProperty="dId" resultType="int" order="AFTER">
    			select LAST_INSERT_ID()
    		</selectKey>
    		insert into testdept set dname=#{dName}
    	</insert>
    	
    	<delete id="delDeptById" parameterType="dept">
    		delete from testdept where did=#{dId}
    	</delete>
    	
    	<update id="updateDeptById" parameterType="dept">
    		update testdept set dname=#{dName} where did=#{dId}
    	</update>
    	
    </mapper>

测试文件

package com.baidu.test;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.List;
    
    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.After;
    import org.junit.Before;
    import org.junit.Test;
    
    import com.baidu.dept.Dept;
    
    public class Test1 {
    	private InputStream inputStream;
    	SqlSessionFactory sessionFactory;
    	SqlSession session;
    	
    	@Before
    	public void Init() throws IOException {
    		inputStream=Resources.getResourceAsStream("sqlMapConfig.xml");
    		sessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
    		session = sessionFactory.openSession();
    	}
    	
    	@Test
    	public void test1() {
    		List<Dept> deptList = session.selectList("test.getDeptList");
    		Dept dept = session.selectOne("test.getDeptById",1);
    		System.out.println(deptList);
    		System.out.println(dept);
    	}
    	
    	@Test
    	public void test2() {
    		List<Dept> deptList = session.selectList("test.getDeptListByMohu","%雄%");
    		System.out.println(deptList);
    	}
    	
    	@Test
    	public void test3() {
    		List<Dept> deptList = session.selectList("test.getDeptListByDept",new Dept(2, "呵呵哒"));
    		System.out.println(deptList);
    	}
    	
    	@Test
    	public void test4() {
    		Integer i = session.selectOne("test.getDeptCount");
    		System.out.println(i);
    	}
    	
    	@Test
    	public void test5() {
    		//session是默认不会自动提交事务操作的，需要手动提交事务
    		Dept dept=new Dept(null, "呵呵哒");
    		int i=session.insert("test.insertDept2", dept);
    		session.commit();
    		System.out.println(dept);
    	}
    	
    	@Test
    	public void test6() {
    		session.delete("test.delDeptById",new Dept(9, "?!"));
    		session.commit();
    	}
    	
    	@Test
    	public void test7() {
    		session.delete("test.updateDeptById",new Dept(8, "老王"));
    		session.commit();
    	}
    	
    	@After
    	public void closeSession() {
    		session.close();
    	}
    }

需要注意：参数是对象时，需要注意\#中的值要和对象里的值一样

代理模式：通过动态代理一个接口来动态创建接口代理对象

sql配置文件：

<?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="com.baidu.mapper.DeptMapper">
    	
    	
    	
    	
    	
    	<select id="getDeptList" resultType="dept">
    		select * from testdept
    	</select>
    	<select id="getDeptListById" resultType="dept" parameterType="dept">
    		select * from testdept where did=#{dId}
    	</select>
    		
    		
    		
    	<select id="getDeptListById2" resultType="dept" parameterType="dept">
    		select * from testdept
    		<where>
    			<if test="dId!=null">
    				and did=#{dId}
    			</if>
    		</where>
    	</select>
    	
    	<select id="getDeptListById3" resultType="dept" parameterType="dept">
    		select * from testdept
    		<where>
    			and did
    			<if test="deptList!=null">
    				<foreach collection="deptList" open="in(" close=")" separator="," item="d">
    					#{d}
    				</foreach>
    			</if>
    		</where>
    	</select>
    	
    	<sql id="getDeptSql">
    		<if test="dId!=null">
    			and did=#{dId}
    		</if>
    	</sql>
    	<select id="getDeptByDept" resultType="dept" parameterType="dept">
    		select * from testdept
    		<where> <include refid="getDeptSql"></include> </where>
    	</select>
    </mapper>

测试文件：

package com.baidu.test;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.ArrayList;
    import java.util.List;
    
    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.After;
    import org.junit.Before;
    import org.junit.Test;
    
    import com.baidu.dept.Dept;
    import com.baidu.mapper.DeptMapper;
    
    public class Test1 {
    	private InputStream inputStream;
    	SqlSessionFactory sessionFactory;
    	SqlSession session;
    	
    	@Before
    	public void init() throws IOException {
    		inputStream=Resources.getResourceAsStream("sqlMapConfig.xml");
    		sessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
    		session = sessionFactory.openSession();
    	}
    	
    	
    	//
    	
    	@Test
    	public void test8() {
    		DeptMapper mapper = session.getMapper(DeptMapper.class);
    		List<Dept> deptList = mapper.getDeptList();
    		System.out.println(deptList);
    	}
    	
    	@Test
    	public void test9() {
    		DeptMapper mapper = session.getMapper(DeptMapper.class);
    		List<Dept> deptListById = mapper.getDeptListById(new Dept(1, null));
    		System.out.println(deptListById);
    	}
    	
    	
    	@Test
    	public void test10() {
    		DeptMapper mapper = session.getMapper(DeptMapper.class);
    		List<Dept> deptListById2 = mapper.getDeptListById2(new Dept(2,null));
    		System.out.println(deptListById2);
    	}
    	
    	@Test
    	public void test11() {
    		DeptMapper mapper = session.getMapper(DeptMapper.class);
    		List<Integer> depts=new ArrayList<>();
    		depts.add(1);
    		depts.add(2);
    		depts.add(3);
    		Dept dept = new Dept(null, null);
    		dept.setDeptList(depts);
    		List<Dept> deptListById = mapper.getDeptListById3(dept);
    		System.out.println(deptListById);
    	}
    	
    	@Test
    	public void test12() {
    		DeptMapper mapper = session.getMapper(DeptMapper.class);
    		Dept deptByDept = mapper.getDeptByDept(new Dept(1, null));
    		System.out.println(deptByDept);
    	}
    	
    	@After
    	public void closeSession() {
    		session.close();
    	}
    }

[70]: /images/20210720/b3a4751a297c4253ab00d560e1450f4a.png