MyBatis 实现 增删改查

今天来实现 mybatis 最基本的增删改查操作：

依旧是 三步：1.config.xml 配置文件    2. mapper.xml 映射配置文件  3.测试

首先1.config.xml 配置文件

<?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>
<!--开发环境 (自己的计算机)  -->
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<!--POOLED：使用连接池 避免打开和关闭数据库的耗时  -->
			<dataSource type="POOLED">
			<!-- 配置数据库信息 -->
				<property name="driver" value="oracle.jdbc.OracleDriver" />
				<property name="url" value="jdbc:oracle:thin:@localhost:1521:orcl" />
				<property name="username" value="sys as sysdba" />
				<property name="password" value="123456" />
			</dataSource>
		</environment>
	</environments>
	<mappers>
	<!-- 加载映射 文件 -->
		<mapper resource="org/cjr/entity/PersonMapper.xml" />
	</mappers>
</configuration>

这个配置文件是固定写法，大部分Mybatis的配置都是这样的。

接下来写映射文件：
 

<?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="org.cjr.entity.PersonMapper">

	<select id="queryPersonById" resultType="org.cjr.entity.Person" parameterType="int">
		select * from Person where id = #{id}
	</select>

	<select id="queryAll" resultType="org.cjr.entity.Person">
		select * from Person 
	</select>

	<insert id="addPerson" parameterType="org.cjr.entity.Person">
	insert into person values(#{id},#{name},#{age})
	</insert>

	<delete id="deletePerson" parameterType="int">
	delete from person where id= #{id}
	</delete>

	<update id="updatePerson" parameterType="org.cjr.entity.Person">
	update person set name=#{name},age=#{age} where id=#{id}
	</update>
	
	
</mapper>

该映射文件 存放了Sql语句 以及 返回值类型等 信息。

最后我们写测试类

package org.cjr.entity;


import java.io.IOException;
import java.io.Reader;
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;

public class testMyBatis {
   public static void queryStudentBySno() throws IOException {
	   //加载配置文件
	      Reader reader = Resources.getResourceAsReader("config.xml");
	       //qlSessionFactory 
	      SqlSessionFactory sqlSessionFactory = new  SqlSessionFactoryBuilder().build(reader);
	      //session- 相当于connection
	      SqlSession session = sqlSessionFactory.openSession();
	      //映射文件中的namespace + id
	     Person person = session.selectOne("org.cjr.entity.PersonMapper.queryPersonById",1);
	   //   Person person = (Person) session.selectOne("org.cjr.entity.PersonMapper.queryAll");
	      System.err.println(person);
	      session.close();
   }
   //查询
   public static void queryAllStudent() throws IOException {
	   //加载配置文件
	      Reader reader = Resources.getResourceAsReader("config.xml");
	       //qlSessionFactory 
	      SqlSessionFactory sqlSessionFactory = new  SqlSessionFactoryBuilder().build(reader);
	      //session- 相当于connection
	      SqlSession session = sqlSessionFactory.openSession();
	      //映射文件中的namespace + id
	     List<Person> persons = session.selectList("org.cjr.entity.PersonMapper.queryAll");
	      System.err.println(persons);
	      session.close();
   }
   //增加
   public static void addStudent() throws IOException {
	   //加载配置文件
	      Reader reader = Resources.getResourceAsReader("config.xml");
	       //qlSessionFactory 
	      SqlSessionFactory sqlSessionFactory = new  SqlSessionFactoryBuilder().build(reader);
	      //session- 相当于connection
	      SqlSession session = sqlSessionFactory.openSession();
	      //映射文件中的namespace + id
	    Person person = new Person(3,"ww",30); 
	int count =  session.insert("org.cjr.entity.PersonMapper.addPerson",person);
	     session.commit();//提交事务
	System.out.println("增加"+count+"个学生");
	      session.close();
   }
   //删除
   public static void deleteStudent() throws IOException {
	   //加载配置文件
	      Reader reader = Resources.getResourceAsReader("config.xml");
	       //qlSessionFactory 
	      SqlSessionFactory sqlSessionFactory = new  SqlSessionFactoryBuilder().build(reader);
	      //session- 相当于connection
	      SqlSession session = sqlSessionFactory.openSession();
	      //映射文件中的namespace + id  
	int count =  session.delete("org.cjr.entity.PersonMapper.deletePerson",3);
	     session.commit();//提交事务
	System.out.println("删除"+count+"个学生");
	      session.close();
   }
   
 //改
   public static void updateStudent() throws IOException {
	   //加载配置文件
	      Reader reader = Resources.getResourceAsReader("config.xml");
	       //qlSessionFactory 
	      SqlSessionFactory sqlSessionFactory = new  SqlSessionFactoryBuilder().build(reader);
	      //session- 相当于connection
	      SqlSession session = sqlSessionFactory.openSession();
	      //映射文件中的namespace + id  
	      Person person = new Person();
	      person.setId(2);
	      person.setName("zzz");
	      person.setAge(99);
	int count =  session.update("org.cjr.entity.PersonMapper.updatePerson",person);
	     session.commit();//提交事务
	System.out.println("修改"+count+"个学生");
	      session.close();
   }
   
   
   public static void main(String[] args) throws IOException {
	    
	   //deleteStudent();
	   //updateStudent();
	   //addStudent();
	   queryAllStudent();
	   
   }
   
}	

 这些方法中 都是通过session对象来 调用 增删改查的方法，相比较 传统的Jdbc方式，mybatis解决了 Sql与代码之间的耦合问题。