java 中MyBatis注解映射的实例详解

java  中MyBatis注解映射的实例详解

１.普通映射 

@Select("select * from mybatis_Student where id=#{id}")
public Student getStudent(int id);
@Insert("insert into mybatis_Student (name, age, remark, pic,grade_id,address_id) values (#{name},#{age},#{remark}, #{pic},#{grade.id},#{address.id})")
public int insert(Student student);
@Update("update mybatis_Student set name=#{name},age=#{age} where id=#{id}")
public int update(Student student);
@Delete("delete from mybatis_Student where id=#{id}")
public int delete(int id);

 ２.结果集映射

@Select("select * from mybatis_Student")
@Results({
  @Result(id=true,property="id",column="id"),
  @Result(property="name",column="name"),
  @Result(property="age",column="age")
})
public List<Student> getAllStudents(); 

 ３.关系映射

     1),一对一

@Select("select * from mybatis_Student")
@Results({
  @Result(id=true,property="id",column="id"),
  @Result(property="name",column="name"),
  @Result(property="age",column="age"),
    @Result(property="address",column="address_id",one=@One(select="com.skymr.mybatis.mappers.AddressMapper.getAddress"))
})
public List<Student> getAllStudents();

    2)一对多

package com.skymr.mybatis.mappers;

import org.apache.ibatis.annotations.Many;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import com.skymr.mybatis.model.Grade;

public interface Grade2Mapper {

  @Select("select * from mybatis_grade where id=#{id}")
  @Results({
    @Result(id=true,column="id",property="id"),
    @Result(column="grade_name",property="gradeName"),
    @Result(property="students",column="id",many=@Many(select="com.skymr.mybatis.mappers.Student2Mapper.getStudentsByGradeId"))
  })
  public Grade getGrade(int id);
}

  Java代码 

package com.skymr.mybatis.mappers;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.skymr.mybatis.model.Student;

public interface Student2Mapper {

  @Select("select * from mybatis_Student where id=#{id}")
  public Student getStudent(int id);
  @Insert("insert into mybatis_Student (name, age, remark, pic,grade_id,address_id) values (#{name},#{age},#{remark}, #{pic},#{grade.id},#{address.id})")
  public int insert(Student student);
  @Update("update mybatis_Student set name=#{name},age=#{age} where id=#{id}")
  public int update(Student student);
  @Delete("delete from mybatis_Student where id=#{id}")
  public int delete(int id);

  @Select("select * from mybatis_Student")
  @Results({
    @Result(id=true,property="id",column="id"),
    @Result(property="name",column="name"),
    @Result(property="age",column="age"),
    @Result(property="address",column="address_id",one=@One(select="com.skymr.mybatis.mappers.AddressMapper.getAddress"))
  })
  public List<Student> getAllStudents();
  @Select("select * from mybatis_Student where grade_id=#{gradeId}")
    @Results({
    @Result(id=true,property="id",column="id"),
    @Result(property="name",column="name"),
    @Result(property="age",column="age"),
    @Result(property="address",column="address_id",one=@One(select="com.skymr.mybatis.mappers.AddressMapper.getAddress"))
  })
  public List<Student> getStudentsByGradeId(int gradeId);
}

 ４.动态sql注解映射

provider类

package com.skymr.mybatis.mappers.provider;

import java.util.Map;

import org.apache.ibatis.jdbc.SQL;

import com.skymr.mybatis.model.Student;

public class StudentDynaSqlProvider {

  public String insertStudent(final Student student){
    return new SQL(){
      {
        INSERT_INTO("mybatis_Student");
        if(student.getName() != null){
          VALUES("name","#{name}");
        }
        if(student.getAge() > 0){
          VALUES("age","#{age}");
        }
      }
    }.toString();
  }

  public String updateStudent(final Student student){
    return new SQL(){
      {
        UPDATE("mybatis_Student");
        if(student.getName() != null){
          SET("name=#{name}");
        }
        if(student.getAge() > 0){
          SET("age=#{age}");
        }
        WHERE("id=#{id}");
      }
    }.toString();
  }

  public String getStudent(final Map<String,Object> map){
    return new SQL(){
      {
        SELECT("*");
        FROM("mybatis_Student");
        if(map.containsKey("name")){
          WHERE("name like #{name}");
        }
        if(map.containsKey("age")){
          WHERE("age=#{age}");
        }
      }
    }.toString();
  }

  public String deleteStudent(){
    return new SQL(){
      {
        DELETE_FROM("mybatis_Student");
        WHERE("id=#{id}");
      }
    }.toString();
  }
}

 Mapper接口

@SelectProvider(type=StudentDynaSqlProvider.class,method="getStudent")
public List<Student> getStudents(Map<String,Object> map);

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