Mybatis增删改查

Mybatis增删改查

在写这个查所有的用户的时候，JavaBean必须得写一个无参数的构造方法，不然查询所有的用户的时候会出现错误。

package demo2;

public class User {

    private int id;
    private String name;
    private int age;
    
    public User(int id, String name, int age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }
    
    public User()
    {
        
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
    }
    
    
    
}

<?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="demo2.userMapper">
    <!-- 
        根据id查询得到一个user对象
     -->
     <select id="getUser" parameterType="int" resultType="demo2.User">
         select * from users where id=#{id}
     </select>
     <!-- 添加一个用户 -->
     <insert id="insertUser" parameterType="demo2.User">
     
     insert into users(name,age)values(#{name},#{age});
     </insert>
     <!-- 修改一个用户的信息 -->
     <update id="updateUser"  parameterType="demo2.User">
     
     update users set name=#{name},age=#{age} where id = #{id}
     
     </update>
     
     <delete id="deleteUser" parameterType="int">
     
     delete from users where id = #{id} 
     </delete>
     
    <select id="selectAllUsers" resultType="demo2.User">
    select * from users
    </select>

     
    
        

     
     
</mapper>

<?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>

    <properties resource="db.properties"/>
    
    
<!-- 
    development : 开发模式
    work : 工作模式
 -->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="${driver}" />
                <property name="url" value="${url}" />
                <property name="username" value="${name}" />
                <property name="password" value="${password}" />
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        
        <mapper resource="demo2/userMapper.xml"/>
        
    </mappers>
</configuration>

package Test;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.util.List;

import demo2.User;

public class Test {

    public static void main(String[] args) {
        String resouse = "conf.xml";
        //读取上上述的config.xml文件
        InputStream is = Test.class.getClassLoader().getResourceAsStream(resouse);
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        SqlSession session = factory.openSession(true);//在这里如果配置成true就自动提交
        String statement = "demo2.userMapper.getUser";
        
        //User user = (User)session.selectOne(statement, 1);
        String statement2 = "demo2.userMapper.updateUser";
        int update = session.update(statement2, new User(1,"张三",14));
       
        //删除User
        String statement3 = "demo2.userMapper.deleteUser";
        int delete = session.delete(statement3, 1);
        //得到所有的用户
        
        String statement4 = "demo2.userMapper.selectAllUsers";
       List<User> list= session.selectList(statement4);
      
        
        
        
        System.out.println(list);

    }

}