MyBatis 实现增删改查

我不是女神ヾ 2023-06-16 07:59 26阅读 0赞

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>
    
    	<environments default="development">
    		<environment id="development">
    			<transactionManager type="JDBC" />
    			
    			<dataSource type="POOLED">
    			
    				<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>
    	
    		<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。