MyBatis开发dao的两种方式

雨点打透心脏的1/2处 2022-06-15 05:39 204阅读 0赞

## 原始dao的开发 ##

需要编写dao接口及其实现类  
需要在dao实现类中注入一个SqlSessionFactory  
  
**user.xml**

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
    <mapper namespace="com.hl.mybatis.first.mapper.UserMapper">
        
        <select id="findUserById" parameterType="int" resultType="com.hl.myabtis.first.beas.User">
            select * FROM user WHERE id = #{id}
        </select>
        
        <select id="findUserByName" parameterType="String" resultType="com.hl.myabtis.first.beas.User">
            select * FROM user WHERE address LIKE '%${value}%'
        </select>
    
        
        <insert id="insertUser" parameterType="com.hl.myabtis.first.beas.User">
            <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
            SELECT LAST_INSERT_ID()
        </selectKey>
            insert into user (username,birthday,sex,address) value(#{username},#{birthday},#{sex},#{address})
        </insert>
        
        <delete id="deleteUser" parameterType="java.lang.Integer">
            delete from user where id = #{value}
        </delete>
        
         <update id="updateUserByID" parameterType="com.hl.myabtis.first.beas.User">
            update user set username = #{username},birthday = #{birthday},sex = #{sex},address = #{address} where id = #{id}
         </update>
    </mapper>

**接口：**

package com.hl.mybatis.first.dao;
    
    
    import java.util.List;
    
    import com.hl.myabtis.first.beas.User;
    
    public interface IUserDAO { 
    
        //根据id查询用户信息
        public User finfUserById(int id) throws Exception;
        //添加用户信息
        public void insertUser(User user);
        //根据id删除用户
        public void deleteUser(int id);
        //根据用户姓名模糊查找
        public List<User> findUserByName(String name);
    }

**接口的实现**

package com.hl.mybatis.first.daoimpl;
    
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    
    import com.hl.myabtis.first.beas.User;
    import com.hl.mybatis.first.dao.IUserDAO;
    
    public class UserDaoImpl implements IUserDAO { 
    
        private SqlSessionFactory sqlSessionFactory;
        //通过构造函数注入sqlSessionFactory
        public UserDaoImpl(SqlSessionFactory sqlSessionFactory){
            this.sqlSessionFactory = sqlSessionFactory;
        }
        @Override
        public User finfUserById(int id) throws Exception {
            SqlSession sqlSession = sqlSessionFactory.openSession();
            User user = sqlSession.selectOne("test.findUserById", id);
            sqlSession.close();
            return user;
        }
    
        @Override
        public void insertUser(User user) {
            SqlSession sqlSession = sqlSessionFactory.openSession();
            sqlSession.insert("test.insertUser", user);
            sqlSession.commit();
            sqlSession.close();
        }
    
        @Override
        public void deleteUser(int id) {
            SqlSession sqlSession = sqlSessionFactory.openSession();
            sqlSession.delete("test.deleteUser", id);
            sqlSession.commit();
            sqlSession.close();
        }
        @Override
        public List<User> findUserByName(String name) {
            SqlSession sqlSession = sqlSessionFactory.openSession();
            List<User> list = sqlSession.selectList("test.findUserByNaem", name);
            sqlSession.close();
            return list;
        }
    
    }

## Mapper代理开发 ##

只需要程序员编写mapper接口，但是程序员在编写mapper.xml文件（映射文件）和mapper接口时需要遵循一些规范。  
规范如下：  
1、mapper.xml中namespace就是mapper接口的类路径全名  
2、mapper.xml中statement的id和mapper接口中的方法名一致  
3、mapper.xml中的statement的parameterType指定输入参数的类型与mapper接口对应方法传递的参数类型相同  
4、mapper.xml中statement的resultType指定输出结果的类型与mapper接口对应方法的返回值类型相同  
  
参考：[http://blog.csdn.net/leisure\_life/article/details/72641788][http_blog.csdn.net_leisure_life_article_details_72641788]

[http_blog.csdn.net_leisure_life_article_details_72641788]: http://blog.csdn.net/leisure_life/article/details/72641788