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

/**

* JPAQueryFactory Bean

* @author zhouzhaodong

*/

@Configuration

public class PeopleQueryConfig {

@Bean

public JPAQueryFactory jpaQuery(EntityManager entityManager) {

return new JPAQueryFactory(entityManager);

}

}

4. 新建实体类

/**

* 实体类

* @author zhouzhaodong

*/

@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

/**

* service

* @author zhouzhaodong

*/

public interface PeopleService {

/**

* 根据id查询

* @param id

* @return

*/

People selectOne(Integer id);

}

6. 新建serviceImpl

/**

* serviceImpl

* @author zhouzhaodong

*/

@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

/**

* controller

* @author zhouzhaodong

*/

@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

/**

* 实现jpaRepository

* @author zhouzhaodong

*/

public interface PeopleRepository extends JpaRepository {

}

9. postman测试

数据库数据如下：

请求结果：

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