Mybatis02_通过Mapper代理实现自定义接口

àì夳堔傛蜴生んèń 2023-03-13 03:54 6阅读 0赞

**Mybatis02\_通过Mapper代理实现自定义接口**

1.  在[Mybatis01\_使用原生接口开发][Mybatis01]工程基础上创建⾃定义接⼝AccountRepository，编写增删改查方法：

package com.blu.repository;
    
    import java.util.List;
    import com.blu.entity.Account;
    
    public interface AccountRepository { 
    	
    	public int save(Account account);
    	public int update(Account account);
    	public int deleteById(long id);
    	public List<Account> findAll();
    	public Account findById(long id);
    	public Account findByNameAndAge(String name, int age);
    }

1.  创建接⼝对应的mapper.xml，编写接⼝⽅法对应的 SQL 语句：

AccountRepository.xml:

<?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.blu.repository.AccountRepository">
    	<insert id="save" parameterType="com.blu.entity.Account">
    		insert into t_account(username,password,age) values(#{username},#{password},#{age})
    	</insert>
    	<update id="update" parameterType="com.blu.entity.Account">
    		update t_account set username = #{username},password = #{password},age = #{age} where id = #{id}
    	</update>
    	<delete id="deleteById" parameterType="long">
    		delete from t_account where id = #{id}
    	</delete>
    	<select id="findAll" resultType="com.blu.entity.Account">
    		select * from t_account
    	</select>
    	<select id="findById" parameterType="java.lang.Long" resultType="com.blu.entity.Account">
    		select * from t_account where id = #{id}
    	</select>
    	<select id="findByNameAndAge" resultType="com.blu.entity.Account">
     		select * from t_account where username = #{arg0} and age = #{arg1}
    	</select>
    </mapper>

mapper编写规则：

namespace用于指定接口的全类名
    insert, delete, update, select四个标签分别对应增删改查
    id用于指定接口中的方法名
    
    parameterType用于指定接口中的方法参数类型
    注：parameterType可以写基本数据类型也可以写成包装类，区别是基本数据类型不接受null值
    当参数不为1时，不需写parameterType，在sql语句中通过索引值取参。
    可以写成#{arg0}，#{arg1}，也可以写成#{param1}，#{param2}
    arg的下标从0开始，param的下标从1开始
    
    resultType用于指定接口中的方法的返回值类型
    添加、修改和删除方法有默认的int类型的resultType（影响的行数）
    注：findAll方法的resultType是List中的泛型类型，而不是List类型

1.  在全局配置⽂件 config.xml 中注册AccountRepository.xml：

1.  save测试方法：

public class Testsave { 
    	public static void main(String[] args) { 
    		InputStream inputStream = Test.class.getClassLoader().getResourceAsStream("config.xml");
    		SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    		SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		// 获取实现接口的代理对象
    		AccountRepository accountRepository = sqlSession.getMapper(AccountRepository.class);
    		Account account = new Account(2L,"李四","111111",24);
    		int result = accountRepository.save(account);
    		//涉及到对数据库进行修改的操作必须要提交事务
    		sqlSession.commit();
    		//关闭连接
    		sqlSession.close();
    	}
    }

运行结果：数据库新增了一条记录  
![在这里插入图片描述][2020051023045361.png]

1.  findById测试方法：

public class TestfindById { 
    	public static void main(String[] args) { 
    		InputStream inputStream = Test.class.getClassLoader().getResourceAsStream("config.xml");
    		SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    		SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		AccountRepository accountRepository = sqlSession.getMapper(AccountRepository.class);
    		Account account = accountRepository.findById(2L);
    		System.out.println(account);
    		sqlSession.close();
    	}
    }

结果：

Account(id=2, username=李四, password=111111, age=24)

1.  findAll测试方法：

public class TestfindAll { 
    	public static void main(String[] args) { 
    		InputStream inputStream = Test.class.getClassLoader().getResourceAsStream("config.xml");
    		SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    		SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		AccountRepository accountRepository = sqlSession.getMapper(AccountRepository.class);
    		List<Account> list = accountRepository.findAll();
    		for (Account account : list){ 
    		    System.out.println(account);
    		}
    		sqlSession.close();
    	}
    }

结果：

Account(id=1, username=张三, password=123123, age=22)
    Account(id=2, username=李四, password=111111, age=24)

1.  update测试方法：

public class Testupdate { 
    	public static void main(String[] args) { 
    		InputStream inputStream = Test.class.getClassLoader().getResourceAsStream("config.xml");
    		SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    		SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		AccountRepository accountRepository = sqlSession.getMapper(AccountRepository.class);
    		Account account = accountRepository.findById(2L);
    		account.setUsername("⼩明");
    		account.setPassword("123456");
    		account.setAge(18);
    		int result = accountRepository.update(account);
    		sqlSession.commit();
    		System.out.println(result);
    		sqlSession.close();
    	}
    }

运行结果：数据库中id为2的数据被修改  
![在这里插入图片描述][20200510233643553.png]  
8. deleteById测试方法：

public class TestdeleteById { 
    	public static void main(String[] args) { 
    		InputStream inputStream = Test.class.getClassLoader().getResourceAsStream("config.xml");
    		SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    		SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		AccountRepository accountRepository = sqlSession.getMapper(AccountRepository.class);
    		int result = accountRepository.deleteById(2L);
    		sqlSession.commit();
    		System.out.println(result);
    		sqlSession.close();
    	}
    }

运行结果：数据库中id为2的数据被删除  
![在这里插入图片描述][20200510234002550.png]  
9. findByNameAndAge测试方法：

public class TestfindByNameAndAge { 
    	public static void main(String[] args) { 
    		InputStream inputStream = Test.class.getClassLoader().getResourceAsStream("config.xml");
    		SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
    		SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		AccountRepository accountRepository = sqlSession.getMapper(AccountRepository.class);
    		Account account = accountRepository.findByNameAndAge("张三", 22);
    		System.out.println(account);
    		sqlSession.close();
    	}
    }

结果：

Account(id=1, username=张三, password=123123, age=22)

[Mybatis01]: https://blog.csdn.net/BLU_111/article/details/105965401
[2020051023045361.png]: /images/20230312/673771c0dbab4c878a0e0c48c8715355.png
[20200510233643553.png]: /images/20230312/b39d864b3b9b4daeb0c3da5c51cc056e.png
[20200510234002550.png]: /images/20230312/eacd467570774d5bafc660c315d4b80a.png