MyBatis入门使用方式

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

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>

	<!-- 加载数据库properties文件 -->
	<properties resource="jdbc.properties"></properties>
	
	<!-- 配置别称，Mybatis已经默认配置一些了比如 _int -->
	<typeAliases>
		<typeAlias type="com.baidu.dept.Dept" alias="dept"/>
	</typeAliases>
	
	<!-- 配置连接数据库环境 -->
  	<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>
	
	<!-- 关联Mapper.xml文件以用来执行sql语句 -->
	<mappers>
		<!-- 这样写是非代理模式下 -->
		<!-- <mapper resource="com/baidu/mapper/DeptMapper.xml"/> -->
		
		<!-- 这样写是代理模式-->
		<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">
 
 <!-- 配置Mapper以用来控制SQL语句 -->
<mapper namespace="test">
	
	<select id="getDeptList" resultType="dept">
		select * from testdept
	</select>
	
	<!-- 加上#表示使用parperment即预编译，使用$表示的statment也就是拼接字符串 -->
	<select id="getDeptById" parameterType="int" resultType="dept">
		select * from testdept where did=#{did}
	</select>
	<select id="getDeptById2" parameterType="int" resultType="dept" >
		select * from testdept where did=${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>
	
	<!-- #后面写什么都行，但是如果参数是个对象，就要和对对象里的 变量写法一样-->
	<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">
		<!-- 返回主键 -->
		<!-- 这里传进来的是对象，所以判断的时候以对象的dId -->
		<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">
 
 <!-- 配置Mapper以用来控制SQL语句 -->
<mapper namespace="com.baidu.mapper.DeptMapper">
	
	
	
	<!-- 使用代理模式....................................................... -->
	
	<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();
	}
}

MyBatis入门使用方式

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