Mybatis学习第二天

1.Mybatis实现CRUD操作

domain包下User类就用了ORM思想。

Dao接口里面的方法：

package com.dao;
import com.domain.User;
import java.util.List;

public interface IUserDao {
    List<User> findAll();
    void saveUser(User user);
    void updateUser(User user);
    void deleteUser(Integer userId);
    User findById(Integer userId);
    List<User> findByName(String username);
    int findTotal();
}

主配置文件：

<?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">
<!--mybaits的主配置文件-->
<configuration>
    <environments default="mysql">
        <!--配置mysql环境-->
        <environment id="mysql">
        <!--配置事务类型-->
            <transactionManager type="JDBC"></transactionManager>
        <!--配置数据源（连接池）-->
            <dataSource type="POOLED">
            <!--配置数据源（连接池）的基本信息-->
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/406"/>
            <property name="username" value="root"/>
            <property name="password" value="123456789"/>
            </dataSource>
        </environment>
    </environments>
        <!--指定映射配置文件的位置，映射配置文件指的是每个dao配置的文件-->
    <mappers>
        <mapper resource="com/dao/IUserDao.xml"></mapper>
    </mappers>
</configuration>

映射配置文件：

<?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="com.dao.IUserDao">
    <!--查询所有-->
    <select id="findAll" resultType="com.domain.User">
        select * from user;
    </select>

    <!--保存用户-->
    <insert id="saveUser" parameterType="com.domain.User">
            <!--配置插入数据后，获取插入数据的id-->
        <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
            select last_insert_id();
        </selectKey>
        insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday});
    </insert>

    <!--更新用户-->
    <update id="updateUser" parameterType="com.domain.User">
        update user set username=#{username},address=#{address},sex=#{sex},birthday=#{birthday} where id =#{id}
    </update>
    
    <!--删除用户-->
    <delete id="deleteUser" parameterType="Integer">
        delete from user where id =#{uid}
    </delete>

    <!--根据id查询用户-->
    <select id="findById" parameterType="INT" resultType="com.domain.User">
        select * from user where id=#{uid}
    </select>

    <!--根据名称模糊查询的语法-->
    <select id="findByName" parameterType="String" resultType="com.domain.User">
        <!--select * from user where username like #{name}-->
        select * from user where username like '%${value}%'
    </select>

    <!--获取用户的总记录条数-->
    <select id="findTotal" resultType="int">
        select count(id) from user;
    </select>
</mapper>

测试类代码：

package com.test;
import ...

public class MybatisTest {

    private InputStream in;
    private SqlSession sqlSession;
    private IUserDao userDao;
    @Before//用于在测试方法执行之前执行
    public void init()throws Exception{
        //1.读取配置文件,生成字节输入流
         in =Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.获取SqlSessionFactory
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(in);
        //3.获取SqlSession对象
        sqlSession = factory.openSession();
        //4.获取dao代理对象
        userDao = sqlSession.getMapper(IUserDao.class);
    }

    @After//用于在测试方法执行之后执行
    public void destroy()throws Exception{
        //提交事务
        sqlSession.commit();
        //6.释放资源
        sqlSession.close();
        in.close();
    }
    @Test
    public void testFindAll(){
        //5.执行查询所有方法
        List<User> users=userDao.findAll();
        for (User user:users){
            System.out.println(user);
        }
    }

    @Test
    public void testSave(){
        User user = new User();
        user.setUsername("mybatis saveuser");
        user.setAddress("SZ");
        user.setSex("男");
        user.setBirthday(new Date());
        System.out.println("保存操作之前,"+user);
        //5.执行保存方法
        userDao.saveUser(user);
        System.out.println("保存操作之后"+user);
    }

    @Test
    public void testUpdate(){
        User user = new User();
        user.setId(41);
        user.setUsername("mybatis update");
        user.setAddress("SZZ");
        user.setSex("女");
        user.setBirthday(new Date());
        //5.执行更新方法
        userDao.updateUser(user);
    }

    @Test
    public void testDelete(){
        //5.执行删除方法
        userDao.deleteUser(41);
    }
    @Test
    public void testFindOne(){
        //5.执行查询一个方法
        User user = userDao.findById(42);
        System.out.println(user);
    }

    @Test
    public void testFindByName(){
        //5.执行模糊查询方法
//        List<User> users = userDao.findByName("%my%");
        List<User> users = userDao.findByName("my");
        for (User user : users){
            System.out.println(user);
        }
    }

    @Test
    public void testFindTotal(){
        //5.执行查询总记录条数方法
        int count =userDao.findTotal();
        System.out.println(count);
    }
}

模糊查询的细节：

第二张图 控制台后面是where like ?