ORM(对象/关系映射)是数据库层非常重要的一部分,有三种常用的映射关系
1.多对一
tbl_clazz
clazz{
id
name
description
grade_id
charge_id
}
clazz {
id
name
description
grade:{
id:
name:
...
},
charge:{
id
name
gender
}
}
提供多对一的查询 -------班级表对应年级表和班主任表
bean
extend
ClazzVM.java
dao
extend
ClazzVMMapper.java(接口)
mapper
extend
ClazzVMMapper.xml
ClazzVMMapper主要实现sql语句,是非常重要的一部分,关键代码如下
<select id="selectByPrimaryKey" parameterType="long" resultMap="ClazzVMMapper"> select * from poll_clazz where id=#{id} </select>
<resultMap type="com.briup.apps.poll.bean.extend.ClazzVM" id="ClazzVMMapper"> <id column="id" property="id"/> <result column="name" property="name"/> <result column="description" property="description"/> <association column="grade_id" property="grade" select="com.briup.apps.poll.dao.GradeMapper.selectByPrimaryKey"> </association> <association column="charge_id" property="charge" select="com.briup.apps.poll.dao.UserMapper.selectByPrimaryKey"> </association> </resultMap>
2.一对多
一对多 查询 ------一个问题包括多个问题选项
查找所有问题,包括问题选项
bean:
package com.briup.apps.poll.bean.extend; import java.util.List; import com.briup.apps.poll.bean.Options; public class QuestionVM { private Long id; private String name; private String questionType; private List<Options> options; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getQuestionType() { return questionType; } public void setQuestionType(String questionType) { this.questionType = questionType; } public List<Options> getOptions() { return options; } public void setOptions(List<Options> options) { this.options = options; } }
dao:
public interface QuestionVMMapper {
List<QuestionVM> selectAll() throws Exception;
List<QuestionVM> selectByQuestionnaireId(long id) throws Exception;
}
QuestionVMMapper.xml(对应实现dao层的selectAll功能)
<mapper namespace="com.briup.apps.poll.dao.extend.QuestionVMMapper"> <select id="selectAll" resultMap="QuestionVMResultMap"> select * from poll_question <!-- id,name,questionType --> </select> <resultMap type="com.briup.apps.poll.bean.extend.QuestionVM" id="QuestionVMResultMap"> <id column="id" property="id"/> <result column="name" property="name" /> <result column="questionType" property="questionType"/> <collection column="id" property="options" javaType="ArrayList" ofType="com.briup.apps.poll.bean.Options" select="selectOptionsByQuestionId"> </collection> </resultMap> <!-- 通过题目id查询问题选项 --> <select id="selectOptionsByQuestionId" resultType="com.briup.apps.poll.bean.Options" parameterType="long"> select * from poll_options where question_id = #{id} </select> </mapper>
service层:
接口
package com.briup.apps.poll.service; import java.util.List; import com.briup.apps.poll.bean.Question; import com.briup.apps.poll.bean.extend.QuestionVM; public interface IQuestionService { //查找所有问题,并查找出问题的所有选项 List<QuestionVM> findAll() throws Exception; //更新或者保存问题,并保存更新问题选项 void saveOrUpdateQuestionVM(QuestionVM questionVM) throws Exception; //删除问题,级联删除选项 void deleteById(long id) throws Exception; //关键字查询 List<Question> query(String keywords) throws Exception; //批量删除题目 void deleteBach(Long[] id)throws Exception; }
接口实现层
package com.briup.apps.poll.service.Impl; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.briup.apps.poll.bean.Options; import com.briup.apps.poll.bean.OptionsExample; import com.briup.apps.poll.bean.Question; import com.briup.apps.poll.bean.QuestionExample; import com.briup.apps.poll.bean.extend.QuestionVM; import com.briup.apps.poll.dao.OptionsMapper; import com.briup.apps.poll.dao.QuestionMapper; import com.briup.apps.poll.dao.extend.QuestionVMMapper; import com.briup.apps.poll.service.IQuestionService; @Service public class QuestionServiceImpl implements IQuestionService { @Autowired private QuestionVMMapper questionVMMapper; @Autowired private OptionsMapper optionsMapper; @Autowired private QuestionMapper questionMapper; @Override public List<QuestionVM> findAll() throws Exception { return questionVMMapper.selectAll(); } /* * 保存或者修改问题,带选项 */ @Override public void saveOrUpdateQuestionVM(QuestionVM questionVM) throws Exception { /* * 1.得到question和options实体,因为保存是分别保存的 * 2.判断是否是保存还是修改操作 * 3.判断题目类型(简答还是选择) * */ Question question=new Question(); question.setId(questionVM.getId()); question.setName(questionVM.getName()); question.setQuestiontype(questionVM.getQuestionType()); List<Options> options=questionVM.getOptions(); if(questionVM.getId()==null){ /*保存操作 * 1.保存题目 * 2.保存选型 */ if(questionVM.getQuestionType().equals("简答题")){ //仅仅保存题目 questionMapper.insert(question); }else{ //先保存题目 questionMapper.insert(question); //获取question的id long id=question.getId(); //保存选项 for(Options option : options){ //遍历所有选项,进行保存 option.setQuestionId(id); optionsMapper.insert(option); } } }else{ //修改 /* * 1.修改题目信息 * 2.删除选项 * 3.重新添加选项 */ questionMapper.updateByPrimaryKey(question); OptionsExample example=new OptionsExample(); example.createCriteria().andQuestionIdEqualTo(question.getId()); optionsMapper.deleteByExample(example); long id=question.getId(); for(Options option : options){ //遍历所有选项,进行保存 option.setQuestionId(id); optionsMapper.insert(option); } } } @Override public void deleteById(long id) throws Exception { questionMapper.deleteByPrimaryKey(id); } @Override public List<Question> query(String keywords) throws Exception { QuestionExample example=new QuestionExample(); example.createCriteria().andNameLike(keywords); return questionMapper.selectByExample(example); } @Override public void deleteBach(Long[] ids) throws Exception { for(long id : ids){ questionMapper.deleteByPrimaryKey(id); } } }
Controll层
package com.briup.apps.poll.web.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.briup.apps.poll.bean.Question;
import com.briup.apps.poll.bean.extend.QuestionVM;
import com.briup.apps.poll.service.IQuestionService;
import com.briup.apps.poll.util.MsgResponse;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
@Api(description="问题模块接口")
@RestController
@RequestMapping("/question")
public class QuestionController {
@Autowired
private IQuestionService questionService;
@ApiOperation(value="删除问题",notes="同时级联删除options")
@GetMapping("deleteQuestionById")
public MsgResponse deleteQuestionQuestionById(long id){
try{
questionService.deleteById(id);
return MsgResponse.success("删除成功", null);
}catch(Exception e){
return MsgResponse.error(e.getMessage());
}
}
@ApiOperation(value="保存或者更新问题",notes="如果id为空,执行保存操作,如果id不为空,执行更新操作")
@PostMapping("saveOrUpdateQuestion")
public MsgResponse saveOrUpdateQuestion(QuestionVM questionVM){
try {
questionService.saveOrUpdateQuestionVM(questionVM);
return MsgResponse.success("success", null);
} catch (Exception e) {
e.printStackTrace();
return MsgResponse.error(e.getMessage());
}
}
@ApiOperation(value="查找所有问题",notes="并查找出所有问题的选项")
@GetMapping("findAllQuestion")
public MsgResponse findAllQuestion(){
try{
List<QuestionVM> list=questionService.findAll();
return MsgResponse.success("success", list);
}catch(Exception e){
e.printStackTrace();
return MsgResponse.error(e.getMessage());
}
}
@ApiOperation(value="批量删除问题",notes="输入问题id")
@GetMapping("deleteBatch")
public MsgResponse deleteBatch(Long[] ids){
try{
questionService.deleteBach(ids);
return MsgResponse.success("success", null);
}catch(Exception e){
e.printStackTrace();
return MsgResponse.error(e.getMessage());
}
}
@ApiOperation(value="关键字查询",notes="输入题目的关键字")
@GetMapping("findByQuery")
public MsgResponse findByQuery(String keywords){
try{
List<Question> list=questionService.query(keywords);
return MsgResponse.success("success", list);
}catch(Exception e){
e.printStackTrace();
return MsgResponse.error(e.getMessage());
}
}
}
3.多对多
问卷模块
1. 查询所有问卷/通过关键字查询问卷(单表)
2. 预览问卷、课调
通过问卷id查询问卷下所有信息(问卷,问题,选项)
2.1 数据库级别表示多对多
问卷 questionnaire
id name
1 主讲问卷
2 辅讲问卷
问题 question
id name
1 授课质量
2 技术水平
3 亲和力
qq
id questionnaire_id question_id
1 1 1
2 1 2
3 1 3
4 2 1
5 2 3
# 通过问卷id查找问卷信息
select * from poll_questionnaire where id =1;
// id name description
# 通过问卷id查找属于问卷的问题信息
select * from poll_question where id in (
select question_id
from poll_qq
where questionnaire_id = 1;
);
2.2 面向对象级别上多对多
QuestionnaireVM{
private Long id;
private String name;
private List<Question> questions;
}
QuestionVM{
private Long id
private String name;
private List<Questionnaire> questionnaires;
}
bean层:
package com.briup.apps.poll.bean.extend; import java.util.List; public class QuestionnaireVM { private Long id; private String name; private String description; private List<QuestionVM> questionVMs; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public List<QuestionVM> getQuestionVMs() { return questionVMs; } public void setQuestionVMs(List<QuestionVM> questionVMs) { this.questionVMs = questionVMs; } }
dao层:
package com.briup.apps.poll.dao.extend; import java.util.List; import com.briup.apps.poll.bean.extend.QuestionnaireVM; public interface QuestionnaireVMMapper { List<QuestionnaireVM> selectById(long id); }
QuestionnaireVM.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.briup.apps.poll.dao.extend.QuestionnaireVMMapper"> <select id="selectById" resultMap="QuestionnaireVMResultMap"> select * from poll_questionnaire where id = #{id} <!-- id,name,description --> </select> <!-- 定义结果集 --> <resultMap type="com.briup.apps.poll.bean.extend.QuestionnaireVM" id="QuestionnaireVMResultMap"> <id column="id" property="id"/> <result column="name" property="name" /> <result column="description" property="description"/> <collection column="id" property="questionVMs" javaType="ArrayList" ofType="com.briup.apps.poll.bean.extend.QuestionVM" select="com.briup.apps.poll.dao.extend.QuestionVMMapper.selectByQuestionnaireId"> </collection> </resultMap> </mapper>
<select id="selectByQuestionnaireId" parameterType="long" resultMap="QuestionVMResultMap"> select * from poll_question where id in( select question_id from poll_qq where questionnaire_id = #{id} ) <!-- id,name,questionType --> </select>
根据问卷id查找所有该问卷的问题,在QuestionVMMapper.java中声名了一个根据问卷id查找所有问题的方法
该方法在QuestionVMMapper.xml中对应的代码为:
<select id="selectByQuestionnaireId" parameterType="long" resultMap="QuestionVMResultMap"> select * from poll_question where id in( select question_id from poll_qq where questionnaire_id = #{id} ) <!-- id,name,questionType --> </select>
service层
接口
package com.briup.apps.poll.service; import java.util.List; import com.briup.apps.poll.bean.Questionnaire; import com.briup.apps.poll.bean.extend.QuestionnaireVM; public interface IQuestionnaireVMService { //查询所有问卷 List<Questionnaire> findAll(); //查询所有问卷及问卷的问题 List<QuestionnaireVM> findQuestionById(long id); }
实现
package com.briup.apps.poll.service.Impl; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.briup.apps.poll.bean.Questionnaire; import com.briup.apps.poll.bean.QuestionnaireExample; import com.briup.apps.poll.bean.extend.QuestionnaireVM; import com.briup.apps.poll.dao.QuestionnaireMapper; import com.briup.apps.poll.dao.extend.QuestionnaireVMMapper; import com.briup.apps.poll.service.IQuestionnaireVMService; @Service public class QuestionnaireVMServiceImpl implements IQuestionnaireVMService{ @Autowired private QuestionnaireMapper questionnaireMapper; @Autowired private QuestionnaireVMMapper questionnaireVMMapper; @Override public List<Questionnaire> findAll() { QuestionnaireExample example=new QuestionnaireExample(); return questionnaireMapper.selectByExampleWithBLOBs(example); } @Override public List<QuestionnaireVM> findQuestionById(long id) { return questionnaireVMMapper.selectById(id); } }
controll层
package com.briup.apps.poll.web.controller; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import com.briup.apps.poll.bean.Questionnaire; import com.briup.apps.poll.bean.extend.QuestionnaireVM; import com.briup.apps.poll.service.IQuestionnaireVMService; import com.briup.apps.poll.util.MsgResponse; import io.swagger.annotations.Api; import io.swagger.annotations.ApiOperation; @Api(description="问卷模块接口") @RestController @RequestMapping("/questionnaire") public class QuestionnaireVMController { @Autowired private IQuestionnaireVMService qnvs; @ApiOperation(value="查找所有问卷",notes="仅仅只查找问卷") @PostMapping("findAllQuestionnaire") public MsgResponse findAllQuestionnaire(){ try{ List<Questionnaire> list=qnvs.findAll(); return MsgResponse.success("success", list); }catch(Exception e){ e.printStackTrace(); return MsgResponse.error(e.getMessage()); } } @ApiOperation(value="预览问卷信息",notes="预览包括问卷上的问题") @GetMapping("findAllQuestionnaireById") public MsgResponse findAllQuestionnaireById(long id){ try{ List<QuestionnaireVM> list=qnvs.findQuestionById(id); return MsgResponse.success("success", list); }catch(Exception e){ e.printStackTrace(); return MsgResponse.error(e.getMessage()); } } }
原文地址:https://www.cnblogs.com/zzuli/p/9245801.html