MyBatis 注解映射 java 中MyBatis注解映射的实例详解

时间:2021-03-29 yunlian0621 人气:0

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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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