更新 spring-boot-jpa-querydsl 进阶使用方式

Author: meteor1993

spring-boot-jpa-querydsl/src/main/java/com/springboot/springbootjpaquerydsl/model/UserModel.java

@@ -4,6 +4,7 @@
 import org.hibernate.annotations.GenericGenerator;
 
 import javax.persistence.*;
+import java.util.Date;
 import java.util.List;
 
 /**
@@ -28,4 +29,6 @@ public class UserModel {
 
     private int age;
 
+    private Date createDate;
+
 }

spring-boot-jpa-querydsl/src/main/java/com/springboot/springbootjpaquerydsl/service/LessonService.java

@@ -11,7 +11,10 @@
  * @Desc:
  */
 public interface LessonService {
+
     List<LessonModel> findLessonList(String name, Date startDate, String address, String userId) throws ParseException;
 
     List<LessonModel> findLessonDynaList(String name, Date startDate, String address, String userId) throws ParseException;
+
+    List<LessonModel> findLessonSubqueryList(String name, String address);
 }

spring-boot-jpa-querydsl/src/main/java/com/springboot/springbootjpaquerydsl/service/UserService.java

@@ -6,27 +6,21 @@
 import java.util.List;
 
 public interface UserService {
-    // 更新
     Long update(String id, String nickName);
 
-    // 删除
     Long delete(String id);
 
-    // 查询字段
     List<String> selectAllNameList();
 
-    // 查询实体
     List<UserModel> selectAllUserModelList();
 
-    // 查询实体并将结果封装至DTO
     List<UserDTO> selectAllUserDTOList();
 
-    // 去重查询
     List<String> selectDistinctNameList();
 
-    // 查询首个实体
     UserModel selectFirstUser();
 
-    // 查询单个实体，如果结果有多个，会抛`NonUniqueResultException`。
     UserModel selectUser(String id);
+
+    String mysqlFuncDemo(String id, String nickName, int age);
 }

spring-boot-jpa-querydsl/src/main/java/com/springboot/springbootjpaquerydsl/service/impl/LessonServiceImpl.java

@@ -1,6 +1,7 @@
 package com.springboot.springbootjpaquerydsl.service.impl;
 
 import com.querydsl.core.BooleanBuilder;
+import com.querydsl.jpa.JPAExpressions;
 import com.querydsl.jpa.impl.JPAQueryFactory;
 import com.springboot.springbootjpaquerydsl.model.LessonModel;
 import com.springboot.springbootjpaquerydsl.model.QLessonModel;
@@ -24,13 +25,15 @@
  */
 @Service
 public class LessonServiceImpl implements LessonService {
+
     @Autowired
     JPAQueryFactory queryFactory;
 
     @Override
     public List<LessonModel> findLessonList(String name, Date startDate, String address, String userId) throws ParseException {
         QLessonModel lessonModel = QLessonModel.lessonModel;
         SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
+        // 多条件查询示例
         return queryFactory.selectFrom(lessonModel)
                 .where(
                         lessonModel.name.like("%" + name + "%")
@@ -46,6 +49,7 @@ public List<LessonModel> findLessonDynaList(String name, Date startDate, String
         QLessonModel lessonModel = QLessonModel.lessonModel;
         SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
 
+        // 动态查询示例
         BooleanBuilder builder = new BooleanBuilder();
 
         if (!StringUtils.isEmpty(name)){
@@ -66,4 +70,18 @@ public List<LessonModel> findLessonDynaList(String name, Date startDate, String
 
         return queryFactory.selectFrom(lessonModel).where(builder).fetch();
     }
+
+    @Override
+    public List<LessonModel> findLessonSubqueryList(String name, String address) {
+        QLessonModel lessonModel = QLessonModel.lessonModel;
+        // 子查询示例，并无实际意义
+        return queryFactory.selectFrom(lessonModel)
+                .where(lessonModel.name.in(
+                        JPAExpressions
+                                .select(lessonModel.name)
+                                .from(lessonModel)
+                                .where(lessonModel.address.eq(address))
+                ))
+                .fetch();
+    }
 }

spring-boot-jpa-querydsl/src/main/java/com/springboot/springbootjpaquerydsl/service/impl/UserServiceImpl.java

@@ -1,9 +1,9 @@
 package com.springboot.springbootjpaquerydsl.service.impl;
 
 import com.querydsl.core.types.Projections;
+import com.querydsl.core.types.dsl.Expressions;
 import com.querydsl.jpa.impl.JPAQueryFactory;
 import com.springboot.springbootjpaquerydsl.dto.UserDTO;
-import com.springboot.springbootjpaquerydsl.model.LessonModel;
 import com.springboot.springbootjpaquerydsl.model.QLessonModel;
 import com.springboot.springbootjpaquerydsl.model.QUserModel;
 import com.springboot.springbootjpaquerydsl.model.UserModel;
@@ -30,31 +30,36 @@ public class UserServiceImpl implements UserService {
     @Override
     public Long update(String id, String nickName) {
         QUserModel userModel = QUserModel.userModel;
+        // 更新
         return queryFactory.update(userModel).set(userModel.nickName, nickName).where(userModel.id.eq(id)).execute();
     }
 
     @Override
     public Long delete(String id) {
         QUserModel userModel = QUserModel.userModel;
+        // 删除
         return queryFactory.delete(userModel).where(userModel.id.eq(id)).execute();
     }
 
     @Override
     public List<String> selectAllNameList() {
         QUserModel userModel = QUserModel.userModel;
+        // 查询字段
         return queryFactory.select(userModel.nickName).from(userModel).fetch();
     }
 
     @Override
     public List<UserModel> selectAllUserModelList() {
         QUserModel userModel = QUserModel.userModel;
+        // 查询实体
         return queryFactory.selectFrom(userModel).fetch();
     }
 
     @Override
     public List<UserDTO> selectAllUserDTOList() {
         QUserModel userModel = QUserModel.userModel;
         QLessonModel lessonModel = QLessonModel.lessonModel;
+        // 连表查询实体并将结果封装至DTO
         return queryFactory
                 .select(
                         Projections.bean(UserDTO.class, userModel.nickName, userModel.age, lessonModel.startDate, lessonModel.address, lessonModel.name)
@@ -68,18 +73,46 @@ public List<UserDTO> selectAllUserDTOList() {
     @Override
     public List<String> selectDistinctNameList() {
         QUserModel userModel = QUserModel.userModel;
+        // 去重查询
         return queryFactory.selectDistinct(userModel.nickName).from(userModel).fetch();
     }
 
     @Override
     public UserModel selectFirstUser() {
         QUserModel userModel = QUserModel.userModel;
+        // 查询首个实体
         return queryFactory.selectFrom(userModel).fetchFirst();
     }
 
     @Override
     public UserModel selectUser(String id) {
         QUserModel userModel = QUserModel.userModel;
+        // 查询单个实体，如果结果有多个，会抛`NonUniqueResultException`。
         return queryFactory.selectFrom(userModel).fetchOne();
     }
+
+    @Override
+    public String mysqlFuncDemo(String id, String nickName, int age) {
+
+        QUserModel userModel = QUserModel.userModel;
+
+        // Mysql 聚合函数示例
+
+        // 聚合函数-avg()
+        Double averageAge = queryFactory.select(userModel.age.avg()).from(userModel).fetchOne();
+
+        // 聚合函数-sum()
+        Integer sumAge = queryFactory.select(userModel.age.sum()).from(userModel).fetchOne();
+
+        // 聚合函数-concat()
+        String concat = queryFactory.select(userModel.nickName.concat(nickName)).from(userModel).fetchOne();
+
+        // 聚合函数-contains()
+        Boolean contains = queryFactory.select(userModel.nickName.contains(nickName)).from(userModel).where(userModel.id.eq(id)).fetchOne();
+
+        // 聚合函数-DATE_FORMAT()
+        String date = queryFactory.select(Expressions.stringTemplate("DATE_FORMAT({0},'%Y-%m-%d')", userModel.createDate)).from(userModel).fetchOne();
+
+        return null;
+    }
 }