[Mybatis学习] 2.接口代理实现的数据库操作

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丰富接口实现更多的操作

public interface IUserDao {
    public List<User> findALL();
    public List<User> findById(int id);
    public List<User> findByName(String username);
    public void saveUser(User u);
    public void updateUser(User u);
    public void deleteUser(int id);
    public List<User> findByQueryBean(QueryBean queryBean);

}

现在我们一下子添加了对数据的增删改和各种的查询操作

对应的Mapper.xml文件也要增加相应的条目

<mapper namespace="mybatis.CRUD.dao.IUserDao">
    <select id="findALL" resultType="mybatis.CRUD.bean.User">
        SELECT * FROM user;
    </select>
    <select id="findById" resultType="mybatis.CRUD.bean.User" parameterType="int">
        SELECT * FROM user WHERE id=#{id} ;
    </select>
    <select id="findByName" resultType="mybatis.CRUD.bean.User" parameterType="java.lang.String">
        SELECT * FROM USER WHERE username  LIKE #{username};
    </select>
    <select id="findByQueryBean" parameterType="mybatis.CRUD.bean.QueryBean" resultType="mybatis.CRUD.bean.User">
        sELECT * FROM user WHERE username LIKE #{user.username};
    </select>
    <insert id="saveUser" parameterType="mybatis.CRUD.bean.User">
        <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
            SELECT last_insert_id();
        </selectKey>
        INSERT INTO user(username,birthday,sex,address) VALUES (#{username},#{birthday},#{sex},#{address});
    </insert>
    <update id="updateUser" parameterType="mybatis.CRUD.bean.User">
        UPDATE user SET username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} WHERE id=#{id};
    </update>
    <delete id="deleteUser" parameterType="int">
        DELETE FROM user WHERE id=#{id};
    </delete>
</mapper>

 另外Mybatis中Sql语句的拼接中有‘#{}’与‘${}’两种形式，其实这两个都是老朋友了

#{}：使用的是PreparedStatement提交sql语句，#{}中的数据就是原来的？对应的位置。

${}：使用的是Statement提交sql语句，${}中的数据会直接拼接进sql语句中。

最后编写测试类测试代码

public class MybatisTest {
    InputStream in;
    SqlSession session;
    IUserDao userDao;
    @Before
    public void init()throws Exception{
        in= Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();
        SqlSessionFactory factory=builder.build(in);
        session=factory.openSession();
        userDao=session.getMapper(IUserDao.class);

    }

    @After
    public void destory() throws IOException {
        session.close();
        in.close();
    }
    @Test
    public void testFindAll() throws Exception {
        List<User> users=userDao.findALL();
        for(User user:users) {
            System.out.println(user.toString());
        }
    }
    @Test
    public void testSaveUser()throws Exception{
        User u=new User();
        u.setUsername("XX");
        u.setSex("男");
        u.setAddress("XX");
        u.setBirthday(new Date());
        System.out.println("保存数据之前的"+u.toString());
        userDao.saveUser(u);
        System.out.println("保存数据之后的"+u.toString());
        System.out.println("获得id："+u.getId());
        session.commit();
    }

    @Test
    public void testUpdateUser()throws Exception{
        User u=new User();
        u.setId(51);
        u.setUsername("XXXXX");
        u.setSex("男");
        u.setAddress("XXXXX");
        u.setBirthday(new Date());
        userDao.updateUser(u);
        session.commit();
    }

    @Test
    public void testDeleteUser()throws Exception{
        userDao.deleteUser(48);
        session.commit();
    }
    @Test
    public void testFindById() throws Exception {
        List<User> users=userDao.findById(51);
        for(User user:users) {
            System.out.println(user.toString());
        }
    }
    @Test
    public void testFindByName() throws Exception {
        List<User> users=userDao.findByName("YF%");
        for(User user:users) {
            System.out.println(user.toString());
        }
    }

    @Test
    public void testFindByQueryBean(){
        QueryBean qb=new QueryBean();
        User user=new User();
        user.setUsername("%X%");
        qb.setUser(user);
        List<User> users=userDao.findByQueryBean(qb);
        for(User u:users) {
            System.out.println(u.toString());
        }
    }

}

<mapper namespace="mybatis.CRUD.dao.IUserDao">
    <select id="findALL" resultType="mybatis.CRUD.bean.User">
SELECT * FROM user;
    </select>
    <select id="findById" resultType="mybatis.CRUD.bean.User" parameterType="int">
SELECT * FROM user WHERE id=#{id} ;
    </select>
    <select id="findByName" resultType="mybatis.CRUD.bean.User" parameterType="java.lang.String">
SELECT * FROM USER WHERE username  LIKE #{username};
    </select>
    <select id="findByQueryBean" parameterType="mybatis.CRUD.bean.QueryBean" resultType="mybatis.CRUD.bean.User">
sELECT * FROM user WHERE username LIKE #{user.username};
    </select>
    <insert id="saveUser" parameterType="mybatis.CRUD.bean.User">
        <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
SELECT last_insert_id();
        </selectKey>
INSERT INTO user(username,birthday,sex,address) VALUES (#{username},#{birthday},#{sex},#{address});
    </insert>
    <update id="updateUser" parameterType="mybatis.CRUD.bean.User">
UPDATE user SET username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} WHERE id=#{id};
    </update>
    <delete id="deleteUser" parameterType="int">
DELETE FROM user WHERE id=#{id};
    </delete>
</mapper>