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
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!--QueryDSL支持-->
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-apt</artifactId>
<scope>provided</scope>
</dependency>
<!--QueryDSL支持-->
<dependency>
<groupId>com.querydsl</groupId>
<artifactId>querydsl-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<!-- 这个插件是为了让程序自动生成query type(查询实体，命名方式为："Q"+对应实体名) -->
<plugin>
<groupId>com.mysema.maven</groupId>
<artifactId>apt-maven-plugin</artifactId>
<version>1.1.3</version>
<executions>
<execution>
<goals>
<goal>process</goal>
</goals>
<configuration>
<outputDirectory>target/generated-sources/java</outputDirectory>
<processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
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<People, Integer> {
}
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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