Mybatis Dao开发

蔚落 2021-12-22 12:43 296阅读 0赞

1 创建项目，lib下引入Mybatis的jar包

![20190613202253534.png][]

2 引入数据库连接的jar包

![20190613202351526.png][]

3 选中所有lib下的包右键Build Path

4 编写Mybatis核心配置文件（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>
    	
    	<environments default="development">
    		<environment id="development">
    			
    			<transactionManager type="JDBC" />
    			
    			<dataSource type="POOLED">
    				<property name="driver" value="com.mysql.jdbc.Driver" />
    				<property name="url"
    					value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />
    				<property name="username" value="root" />
    				<property name="password" value="123456" />
    			</dataSource>
    		</environment>
    	</environments>
    	
    	<mappers>
    	<mapper resource="sqlmap/User.xml"/>
    	</mappers>
    </configuration>

5 创建POJO类

public class User{
    	private Integer id;
    	private String username;
    	private String sex;
    	private Date birthday;
    	private String address;
        .......get/set方法........
    
    }

6 创建sql映射User.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="test">
    
    
    	
    
    	<select id="findUserById" parameterType="Integer" resultType="com.entity.User">
    		select * from user where id = #{v}
    	</select>
    
    
    	
    
    
    	<select id="findUserByUsername" parameterType="String"
    		resultType="com.entity.User">
    		
    		
    		select * from user where username like '%${value}%'
    	</select>
    
    	
    
    	<insert id="insertUser" parameterType="com.entity.User">
    		
    		<selectKey keyProperty="id" resultType="Integer" order="AFTER">
    			select LAST_INSERT_ID()
    		</selectKey>
    		insert into user(username,sex,birthday,address)
    		values(#{username},#{sex},#{birthday},#{address})
    	</insert>
    
    	
    	
    
    	<update id="updateUserByID" parameterType="com.entity.User">
    	update user set username=#{username},sex=#{sex},birthday=#{birthday},address=#{address} where id=#{id}
    	</update>
    
    
    	
    
    	<delete id="deleteUserById" parameterType="Integer">
    	 delete from user where id = #{value}
    	</delete>
    </mapper>

7 加载映射文件

![20190613203335406.png][]

8 编写 Dao层

package com.dao;
    
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    
    import com.entity.User;
    
    public class UserDaoImpl implements UserDao {
    		//注入SqlSessionFactory
    		 private SqlSessionFactory sqlSessionFactory;
    		 //构造方法
    		public UserDaoImpl(SqlSessionFactory sqlSessionFactory) {
    			this.sqlSessionFactory = sqlSessionFactory;
    		}
    		//通过用户ID查询一个用户
    		public User selectUserById(Integer id) {
    			SqlSession sqlSession = sqlSessionFactory.openSession();
    			User user = sqlSession.selectOne("test.findUserById", id);
    			return user;
    
    		}
    		//根据用户名称模糊查询用户列表
    		public List<User> selectByUserName(String username) {
    			SqlSession sqlSession = sqlSessionFactory.openSession();
    			List<User> users = sqlSession.selectList("findUserByUsername", username);
    			return users;
    
    		}
    		 
    }

9 编写测试类

package com.junit;
    
    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.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.Before;
    import org.junit.Test;
    
    import com.dao.UserDao;
    import com.dao.UserDaoImpl;
    import com.entity.User;
    
    public class MybatisDaoTest {
    	public SqlSessionFactory sqlSessionFactory;
    	@Before
    	public void before() throws IOException {
    	    String resource = "sqlMapConfig.xml";
    		InputStream inputStream = Resources.getResourceAsStream(resource);
    		sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    
    	}
    	@Test
    	public void testById() {
    		UserDao userDao = new UserDaoImpl(sqlSessionFactory);
    		User user = userDao.selectUserById(10);
    		System.out.println(user);
    	}
    	@Test
    	public void testByName() {
    		UserDao userDao = new UserDaoImpl(sqlSessionFactory);
    		List<User> list = userDao.selectByUserName("三");
    		for (User user : list) {
    		System.out.println(user);	
    		}
    	}
    }

[20190613202253534.png]: /images/20211220/006fa925cda049e5bc9b407aaad17b01.png
[20190613202351526.png]: /images/20211220/93b672b7bfff415da8ac3b4e81a1d6b1.png
[20190613203335406.png]: /images/20211220/d292ebed529944c1917df81e3396ae16.png