Spring Boot整合QueryDSL的实现示例

之前研究Jooq，今天来研究一下搭配JPA的QueryDSL吧。

简介

Querydsl 是一个Java开源框架用于构建类型安全的SQL查询语句。它采用API代替拼凑字符串来构造查询语句。可跟 Hibernate 和 JPA 等框架结合使用。

新建Spring Boot项目

。。。还说啥？

1. pom.xml

    
      org.springframework.boot
      spring-boot-starter-data-jpa
    
    
    
      org.springframework.boot
      spring-boot-starter-web
    
 
    
      mysql
      mysql-connector-java
      runtime
    
 
    
    
      com.querydsl
      querydsl-apt
      provided
    
    
    
    
      com.querydsl
      querydsl-jpa
    
 
    
      org.springframework.boot
      spring-boot-starter-test
      test
      
 
   org.junit.vintage
   junit-vintage-engine
 
      
    
  
 
  
    
      
 org.springframework.boot
 spring-boot-maven-plugin
      
	  
      
 com.mysema.maven
 apt-maven-plugin
 1.1.3
 
   
     
process
     
     
target/generated-sources/java
com.querydsl.apt.jpa.JPAAnnotationProcessor
     
   
 
      
    
  

2. application.yml

server:
 port: 8888
spring:
 datasource:
  url: jdbc:mysql://IP地址:3306/querydsl?characterEncoding=UTF-8
  username: 用户名
  password: 密码
 jpa:
  show-sql: true # 控制台打印SQL
  hibernate:
   ddl-auto: update

3. JPAQueryFactory Bean

@Configuration
public class PeopleQueryConfig {
  @Bean
  public JPAQueryFactory jpaQuery(EntityManager entityManager) {
    return new JPAQueryFactory(entityManager);
  }
}

4. 新建实体类

@Entity
@Table(name="people")
public class People {
 
  @Id
  @Column(name="id")
  @GeneratedValue
  private Integer id;
 
  @Column(name="name")
  private String name;
 
  @Column(name="age")
  private Integer age;
 
  @Column(name="address")
  private String address;
 
  public Integer getId() {
    return id;
  }
 
  public void setId(Integer id) {
    this.id = id;
  }
 
  public String getName() {
    return name;
  }
 
  public void setName(String name) {
    this.name = name;
  }
 
  public Integer getAge() {
    return age;
  }
 
  public void setAge(Integer age) {
    this.age = age;
  }
 
  public String getAddress() {
    return address;
  }
 
  public void setAddress(String address) {
    this.address = address;
  }
}

5. 新建service

public interface PeopleService {
 
  
  People selectOne(Integer id);
 
}

6. 新建serviceImpl

@Service
public class PeopleServiceImpl implements PeopleService {
 
  @Resource
  JPAQueryFactory queryFactory;
 
  @Override
  public People selectOne(Integer id) {
    QPeople people = QPeople.people;
    return queryFactory.selectFrom(people).where(people.id.eq(id)).fetchOne();
  }
}

7. 新建controller

@RestController
public class PeopleController {
 
  @Resource
  PeopleService peopleService;
 
  @RequestMapping("/selectById")
  public People selectById(){
    return peopleService.selectOne(0);
  }
 
}

8. 新建repository，可以使用JPA原有的功能

public interface PeopleRepository extends JpaRepository {
}

9. postman测试

数据库数据如下：

请求结果：

Github代码地址：https://github.com/zhouzhaodong/springboot/tree/master/querydsl

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