简单的增删改查:

接着MyBytis快速入门(一)的项目继续做

mapper文件

<?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="userMapper">
    <!--查询用户-->
    <select id="findAll" resultType="com.itheibai.entity.User">
        select * from user
    </select>
    <!--插入用户-->
    <insert id="save" parameterType="com.itheibai.entity.User">
        insert into user values (#{id},#{username},#{password})
    </insert>
    <!--更新用户-->
    <update id="updateById" parameterType="com.itheibai.entity.User">
        update user set username=#{username},password=#{password} where id=#{id}
    </update>
    <!--删除用户-->
    <delete id="deleteById" parameterType="Integer">
        delete from user where id=#{id}
    </delete>
</mapper>

测试类

package com.itheibai.test;
import com.itheibai.entity.User;
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 org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class MyBatisTest {
    /**
     * 删除操作
     * @throws IOException
     */
    @Test
    public void test4() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        int delete = sqlSession.delete("userMapper.deleteById", 5);
        System.out.println(delete);
        //提交事务
        sqlSession.commit();
        sqlSession.close();
    }
    /**
     * 更新操作
     * @throws IOException
     */
    @Test
    public void test3() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //构造模拟要更改的user数据
        User user = new User();
        user.setId(5);
        user.setUsername("李八");
        user.setPassword("654321");
        int update = sqlSession.update("userMapper.updateById", user);
        System.out.println(update);
        //提交事务
        sqlSession.commit();
        sqlSession.close();
    }
    /**
     * 插入操作
     * @throws IOException
     */
    @Test
    public void test2() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //构造模拟插入 user 的数据
        User user = new User();
        user.setUsername("李七");
        user.setPassword("123456");
        int insert = sqlSession.insert("userMapper.save", user);
        System.out.println(insert);
        //提交事务
        sqlSession.commit();
        //释放资源
        sqlSession.close();
    }
    /**
     * 查询所有用户
     * @throws IOException
     */
    @Test
    public void test1() throws IOException {
        //获得核心配置文件,导入的是相对地址
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        //获取session工厂对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //获得会话对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //执行操作 参数： namespace+id
        List<User> userList = sqlSession.selectList("userMapper.findAll");
        //打印数据
        System.out.println(userList);
        //释放资源
        sqlSession.close();
    }
}

注意事项:

插入语句使用insert标签

在映射文件中使用parameterType属性指定要插入的数据类型

Sql语句中使用#{实体属性名}方式引用试题中的属性值

插入操作使用的API是sqlSession.insert(“命名空间.id”,实体对象)

插入操作涉及数据库数据变化,所以要使用sqlSession对象显示的提交事务,即sqlSession.commit()