1.先在resources目录下绑定好接口,否则无法找到接口,注意使用注解sql就不在配置接口对应的xml文件了。
<!--绑定接口-->
<mappers>
<mapper class="com.test.dao.UserMapper"/>
</mappers>
2.我这里直接封装了一个工具类MybatisUtils调用SqlSession,注意把事务开启,以后接不用手动提交SQL语句了
public static SqlSession getSqlSession(){
SqlSession sqlSession = sqlSessionFactory.openSession(true); // 自动提交事务为true
return sqlSession;
}
3.使用注解配置好对应的接口
public interface UserMapper {
// 查询全部用户
@Select("select * from user")
List<User> getUsers();
// 方法存在多个参数,所有的参数前面必须加@Param()注解
// 通过id和name查询用户
@Select("select * from user where id = #{id} and name = #{name}")
User getUsersByIdName(@Param("id") int id,@Param("name") String name);
// 插入用户
@Insert("insert into user(id,name,pwd) values(#{id},#{name},#{pwd})")
int addUser(User user);
// 修改用户
@Update("update user set name = #{name} where id = #{id}")
int updateUser(Map<String,Object> map);
// 删除用户
@Delete("delete from user where id = #{id}")
int deleteUser(@Param("id") int id);
}
4.编写测试类测试对应的接口
public class UserMapperTest {
@Test
public void getUserByLimit(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List<User> users = userMapper.getUsers();
for(User user : users){
System.out.println(user);
}
sqlSession.close();
}
@Test
public void getUsersByIdName(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.getUsersByIdName(1, "zhangsan");
System.out.println(user);
}
@Test
public void addUser(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
int i = userMapper.addUser(new User(6, "zhaoliu", "123456"));
if(i>0){
System.out.println("插入成功");
}
}
@Test
public void updateUser(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
Map<String,Object> map = new HashMap<String,Object>();
map.put("name","赵六");
map.put("id",6);
int i = userMapper.updateUser(map);
if(i>0){
System.out.println("更新成功");
}
}
@Test
public void deleteUser(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
int i = userMapper.deleteUser(6);
if(i>0){
System.out.println("删除成功");
}
}
}
笔记:
关于@Param()注解
1.基本类型的参数或者String类型,需要加上
2.引用类型不需要加
3.如果只有一个基本类型的参数,可以忽略,但建议加上
4.有多个基本类型的参数,必须加上
5.我们在SQL中引用的就是我们这里的@Param(“id”)中设定的属性名
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