MyBatis入门程序

电玩女神 2022-05-16 13:40 253阅读 0赞

**准备MyBatis环境**

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**创建mybatis项目，并导入MyBatis、MySql JAR包**

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**创建mybatis-config.xml（通过xml构建SqlSessionFactory）**

<?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="mysql">
    		<environment id="mysql">
    			
    			<transactionManager type="jdbc"/>
    			
    			<dataSource type="POOLED">
    				<property name="driver" value="com.mysql.jdbc.Driver"/>
    				<property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
    				<property name="username" value="root"/>
    				<property name="password" value="root"/>
    			</dataSource>
    		</environment>
    	</environments>
    	
    	<mappers>
    		<mapper resource="com/mapper/UserMapper.xml"/>
    	</mappers>
    </configuration>

**创建User**

package com.po;
    public class User {
    	private Integer uid;
    	private String username;
    	private String password;
    	public Integer getUid() {
    		return uid;
    	}
    	public void setUid(Integer uid) {
    		this.uid = uid;
    	}
    	public String getUsername() {
    		return username;
    	}
    	public void setUsername(String username) {
    		this.username = username;
    	}
    	public String getPassword() {
    		return password;
    	}
    	public void setPassword(String password) {
    		this.password = password;
    	}
    	@Override
    	public String toString() {
    		return "User [uid=" + uid + ", username=" + username + ", password=" + password + "]";
    	}
    }

**创建UserMapper.xml（用xml实现映射器）**

<?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.mapper.UserMapper">	
    	
    	<insert id="adduser" parameterType="com.po.User" useGeneratedKeys="true">
    		insert into t_user(uid,username,password) values(#{uid},#{username},#{password})
    	</insert>
    	
    	<delete id="deleteUser" parameterType="Integer">
    		delete from t_user where uid=#{uid}
    	</delete>
    	
    	<update id="updateUser" parameterType="com.po.User">
    		update t_user set username=#{username},password=#{password} where uid=#{uid}
    	</update>
    	
    	<select id="getUserById" parameterType="Integer" resultType="com.po.User">
    		select * from t_user where uid=#{uid}
    	</select>
    	<select id="getusers" resultType="com.po.User">
    		select * from t_user
    	</select>
    </mapper>

**创建UserDao**

package com.dao;
    import java.io.IOException;
    import java.io.InputStream;
    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;
    import com.po.User;
    public class UserDao {
    	private static SqlSession session;
    	private static List<User> users;
    	private static User user;
    	
    	public static void getUsers(){
    		users=session.selectList("com.mapper.UserMapper.getusers");
    		session.commit();
    		session.close();
    	}
    
    	public static void main(String[] args) throws IOException {
    		//读取配置文件
    		InputStream is=Resources.getResourceAsStream("mybatis-config.xml");
    		//根据配置文件构建SqlSessionFactory
    		SqlSessionFactory sessionFactory=new SqlSessionFactoryBuilder().build(is);
    		//通过SqlSessionFactory创建SqlSession
    		session=sessionFactory.openSession();
    
    		getUsers();
    		for (User use : users) {
    			System.out.println(use);
    		}
    	}
    }

**查询所有用户**

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[70]: /images/20220516/29ed8bb4d03a4b23a15d251088e30366.png
[70 1]: /images/20220516/2d8df6ae6fff4527b7c7c5dc90f98772.png
[70 2]: /images/20220516/b86b3cd667ba4d418b3ccc4a17f5ba74.png