MyBatis框架之注解开发

Posted 2021-12-05 qingmuchuanqi48

MyBatis注解开发

@Insert注解
注解属性value:写入SQL语句

@Options注解
实现添加新数据的主键封装
注解属性
useGeneratedKeys：使用生成的主键，配置为true
keyProperty：主键封装的pojo对象属性

@SelectKey注解
实现添加新数据的主键封装
注解属性
statement：要执行的SQL语句
before：在添加SQL语句之前还是之后进行，配置为false

keyProperty：主键封装的pojo对象属性

注解实现添加数据

UserMapper接口

//新增用户数据
@Insert("insert into user(username,sex,birthday,address)values(#
{username},#{sex},#{birthday},#{address})")
void saveUser(User user);

UserMapper测试

/**
* 注解开发
* 添加用户数据
*/
@Test
public void testSaveUser(){
SqlSession sqlSession = sqlSessionFactory.openSession();
User user = new User();
user.setUsername("孙权");
user.setSex("1");
user.setBirthday(new Date());
user.setAddress("东吴");
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
userMapper.saveUser(user);
sqlSession.commit();
System.out.println(user);
sqlSession.close();
}

@Update注解
注解属性value:写入SQL语句
注解实现更新数据
UserMapper接口

//跟新用户
@Update("update user set username=#{username},sex=#{sex},birthday=#
{birthday},address=#{address} where id=#{id}")
void updateUser(User user);

UserMapper测试

/**
* 注解开发
* 更新用户数据
*/
@Test
public void testUpdateUser(){
SqlSession sqlSession = sqlSessionFactory.openSession();
User user = new User();
user.setId(21);
user.setUsername("孙策");
user.setSex("2");
user.setBirthday(new Date());
user.setAddress("江东");
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
userMapper.updateUser(user);
sqlSession.commit();
sqlSession.close();
}

@Delete注解
注解属性value:写入SQL语句
注解实现删除数据
UserMapper接口

//删除用户
@Delete("delete from user where id = #{id}")
void deleteUser(int id);

UserMapper测试

/**
* 注解开发
* 更新用户数据
*/
@Test
public void testDeleteUser(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
userMapper.deleteUser(21);
sqlSession.commit();
sqlSession.close();
}

@Select注解
注解属性value:写入SQL语句
注解实现主键查询用户数据
UserMapper接口

//主键查询用户
@Select("select id,username,sex,birthday,address from user where id =
#{id}")
User queryUserById(int id);

UserMapper测试

/**
* 注解开发
* 主键查询用户
*/
@Test
public void testQueryUserById(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.queryUserById(1);
System.out.println(user);
sqlSession.close();
}

注解实现查询全部用户数据

UserMapper接口

//查询全部用户
@Select("select id,username,sex,birthday,address from user")
List<User> queryUserByList();

UserMapper测试

/**
* 注解开发
* 查询全部用户
*/
@Test
public void testQueryUserByList(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List<User> userList = userMapper.queryUserByList();
if (userList != null && userList.size() > 0){
for (User user : userList){
System.out.println(user);
}
}
sqlSession.close();
}

动态SQL语句之where和if

UserMapper接口

//多条件查询用户
@Select("<script>select id,username,sex,birthday,address from user" +
"<where>" +
"<if test = \"sex != null and sex != ‘‘\">" +
" and sex = #{sex}" +
"</if>" +
"<if test = \"username != null and username != ‘‘\">" +
" and username like #{username}" +
"</if>" +
"</where></script>")
List<User> queryUserByWhere(User user);

UserMapper测试

/**
* 注解开发
* 多条件查询用户信息
*/
@Test
public void testQueryUserByWhere(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = new User();
user.setSex("2");
user.setUsername("%王%");
List<User> userList = userMapper.queryUserByWhere(user);
if(userList != null && userList.size() > 0){
for(User user1 : userList){
System.out.println(user1);
}
}
sqlSession.close();
}

动态SQL语句之foreach

UserMapper接口

@Select("<script>select id,username,sex,birthday,address from user" +
"<foreach collection = \"list\" open = \"where id in(\" close
= \")\" separator = \",\" item = \"item\">" +
"#{item}" +
"</foreach>" +
"</script>")
List<User> queryUserByListIds(List<Integer> ids);

UserMapper测试

/**
* 注解开发
* 传入List集合，查询用户数据
*/
@Test
public void testQueryUserByListIds(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List<Integer> ids = new ArrayList<Integer>();
ids.add(1);
ids.add(2);
ids.add(3);
List<User> userList = userMapper.queryUserByListIds(ids);
if(userList != null && userList.size() > 0){
for(User user : userList){
System.out.println(user);
}
}
sqlSession.close();
}

一对一的注解开发

@Results注解
配置手动映射，取代resultMap标签
@Result注解
配置手动映射，取代result标签

OrdersMapper接口

//根据订单查询用户，一对一查询
@Select(" SELECT o.id,o.user_id,o.number,o.createtime,o.note FROM
orders o")
@Results({
//配置主键映射，id默认false,不是主键
@Result(id = true,column = "id",property = "id"),
//配置其他映射关系
@Result(column = "user_id",property = "userId"),
@Result(column = "number",property = "number"),
@Result(column = "createtime",property = "createtime"),
@Result(column = "note",property = "note"),
/*
配置关联查询用户表
property查询的pojo对象哪个属性做为条件查询
这个属性还是个pojo对象
column查询条件的pojo对象的属性
@One注解配置一对一的另一个查询语句
此语句需要对应的接口方法出现
*/
@Result(column = "user_id",property = "user",javaType =
User.class,
one = @One(select =
"com.itheima.mapper.UserMapper.queryUserByUserId",fetchType =
FetchType.LAZY))
})
List<Orders> queryOrdersUser();

UserMapper接口

@Select("select id,username,sex,birthday,address from user where id=#
{user_Id}")
User queryUserByUserId(Integer id);

OrdersMapp接口测试

/**
* 注解开发
* 一对一延迟加载测试
*/
@Test
public void testQueryOrdersUser(){
SqlSession sqlSession = sqlSessionFactory.openSession();
OrdersMapper ordersMapper =
sqlSession.getMapper(OrdersMapper.class);
List<Orders> ordersList = ordersMapper.queryOrdersUser();
if(ordersList != null && ordersList.size() > 0){
for(Orders orders : ordersList){
System.out.println(orders);
System.out.println(orders.getUser());
}
}
sqlSession.close();
}

一对多注解开发
UserMapper接口

//用户查询订单，一对多
@Select("select id,username,sex,birthday,address from user")
@Results({
@Result(id = true,column = "id",property = "id"),
@Result(column = "username",property ="username" ),
@Result(column = "sex",property ="sex" ),
@Result(column = "birthday",property ="birthday" ),
@Result(column = "address",property ="address" ),
@Result(column = "id",property = "ordersList",javaType =
List.class,
many = @Many(select =
"com.itheima.mapper.OrdersMapper.queryOrdersByUserId",fetchType =
FetchType.LAZY))
})
List<User> queryUserOrders();

OrdersMapper接口

//用户查询订单，一对多
@Select("select number,createtime from orders where user_id = #
{user_id}" )
List<Orders> queryOrdersByUserId(Integer user_id);

UserMapper接口测试

/**
* 注解开发
* 查询用户下的订单，一对多
*/
@Test
public void testQueryUserOrders(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List<User> userList = userMapper.queryUserOrders();
if(userList != null && userList.size() > 0){
for(User user : userList){
System.out.println(user);
System.out.println(user.getOrdersList());
}
}
sqlSession.close();
}