myBatis系列之二:以接口方式交互数据
myBatis系列之四:关联数据的查询
myBatis系列之五:与Spring3集成
myBatis系列之六:与SpringMVC集成
myBatis系列之七:事务管理
1. 查询
myBatis系列之二:以接口方式交互数据实现了单条记录的查询,这里查询一组记录:
IUserMapper接口添加下面方法:
List<User> getUsers(String name);
在User.xml中添加:
<resultMap type="User" id="userList"><!-- type为返回列表元素的类全名或别名 --> <id column="id" property="id" /> <result column="name" property="name" /> <result column="age" property="age" /> <result column="address" property="address" /> </resultMap> <select id="getUsers" parameterType="string" resultMap="userList"><!-- resultMap为上面定义的User列表 --> select * from `user` where name like #{name} </select>
测试方法:
@Test public void queryListTest() { SqlSession session = sqlSessionFactory.openSession(); try { IUserMapper mapper = session.getMapper(IUserMapper.class); List<User> users = mapper.getUsers("%a%"); // %在sql里代表任意个字符。 for (User user : users) { log.info("{}: {}", user.getName(), user.getAddress()); } } finally { session.close(); } }
2. 新增
IUserMapper接口添加下面方法:
int addUser(User user);
User.xml添加:
<insert id="addUser" parameterType="User" useGeneratedKeys="true" keyProperty="id"><!-- useGeneratedKeys指定myBatis使用数据库自动生成的主键,并填充到keyProperty指定的属性上。如果未指定,返回对象拿不到生成的值 --> insert into user(name,age,address) values(#{name},#{age},#{address}) </insert>
测试方法:
@Test public void addUserTest() { User user = new User("Lucy", 102, "Happy District"); SqlSession session = sqlSessionFactory.openSession(); try { IUserMapper mapper = session.getMapper(IUserMapper.class); int affectedCount = mapper.addUser(user); session.commit(); // 默认为不自动提交。调用session.getConnection().getAutoCommit()查看 log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId()); } finally { session.close(); } }
3. 更新
接口添加方法:
int updateUser(User user);
User.xml添加:
<update id="updateUser" parameterType="User"> update `user` set name=#{name}, age=#{age}, address=#{address} where id=#{id} </update>
测试方法:
@Test public void updateUserTest() { SqlSession session = sqlSessionFactory.openSession(); try { IUserMapper mapper = session.getMapper(IUserMapper.class); User user = mapper.getUserById(8); user.setAddress("Satisfied District"); int affectedCount = mapper.updateUser(user); // 除了要修改的属性外,user的其它属性也要赋值,否则这些属性会被数据库更新为初始值(null或0等),可以先查询一次,但这样会增加和数据库不必要的交互。后面的条件判断能避免此问题。 log.info("Affected count: {}", affectedCount); session.commit(); } finally { session.close(); } }
4. 删除
接口添加方法:
int deleteUser(int id);
User.xml添加:
<delete id="deleteUser" parameterType="int"> delete from `user` where id=#{id} </delete>
测试方法:
@Test public void deleteUserTest() { SqlSession session = sqlSessionFactory.openSession(); try { IUserMapper mapper = session.getMapper(IUserMapper.class); int affectedCount = mapper.deleteUser(8); log.info("Affected count: {}", affectedCount); session.commit(); } finally { session.close(); } }
参考:
http://www.yihaomen.com/article/java/305.htm