@Insert：实现新增
@Select：实现查询
@Update：实现更新
@Delete：实现删除
@Result：实现结果集的封装
@Results：可以与Result一起使用，实现多个结果集的封装
@ResultMap：实现引用@Results定义的封装
@One：实现一对一结果集的封装
@Many：实现一对多结果集的封装
@SelectProvider：实现动态SQL映射
@CacheNamespace：实现注解二级缓存的使用
在使用Mybatis注解的时候需要首先配置Mybatis配置文件中的mappers。
<mappers> <package name="org.lanqiao.dao"/> </mappers>
//不需要返回主键
public interface StudentMapper{ @Insert("insert into student (stud_id, name, email, addr_id, phone)values(#{studId},#{name},#{email},#{address.addrId},#{phone})") int insertStudent(Student student); }
//MySQL数据库返回主键 public interface StudentMapper{ @Insert("insert into student (name,email,addr_id,phone)values(#{name},#{email},#{address.addrId},#{phone})") @Options(useGeneratedKeys=true,keyProperty="studId") int insertStudent(Student student); }
//Oracle数据库返回主键 public interface StudentMapper{ @Insert("insert into student (name,email,addr_id,phone)values(#{name},#{email},#{address.addrId},#{phone})") @SelectKey(statement="select stud_id_seq.nextval from dual",keyProperty="studId",resultType=int.calss,before=true) int insertStudent(Student student); }
//更新操作 @Update("update students set name=#{name},email=#{email}") int updateStudent(Student student); //删除操作 @Delete("delete form students where stud_id=#{studId}") int deleteStudent(int studId) //查询操作 @Select("select name,email,phone from students where stud_id=#{studId}") Student findStudentById(Integer studId);
@Select("select name,email,phone from students where stud_id=#{studId}")
@Results({
@Result(id=true,column="stud_id",property="studId"),
@Result(column="name",property="name"),
@Result(column="email",property="email"),
@Result(column="phone",property="phone")
})
Student findStudentById(Integer studId);
结果注解有一个缺点，就是在一个查询方法前面都要写一遍，不能重用。解决这个问题方案是：
定义一份结果映射文件如下所示：
<mapper namespace="com.mybatis3.mappers.StudentMapper">
<resultMap type="Student" id="StudentResult">
.......
</resultMap>
@Select("select name,email,phone from students where stud_id=#{studId}")
@ResultMap("com.mybatis3.mappers.StudentMapper.StudentResult")
Student findStudentById(Integer studId);
方式一：
@Select("<script>select * from user <if test=\"id !=null \">where id = #{id} </if></script>")
public List<User> findUserById(User user);
方式二：
@Mapper
public interface MybatisDao {
//使用UserDaoProvider类的findUserById方法来生成sql
@SelectProvider(type = UserDaoProvider.class, method = "findUserById")
public List<User> findUserById(User user);
class UserDaoProvider {
public String findUserById(User user) {
String sql = "SELECT * FROM user";
if(user.getId()!=null){
sql += " where id = #{id}";
}
return sql;
}
}
}
原文：https://www.cnblogs.com/david1216/p/13639935.html