# Spring Boot Data JPA 排序教程 > 原文： [http://zetcode.com/springboot/datajpasort/](http://zetcode.com/springboot/datajpasort/) Spring Boot Data JPA 排序教程展示了如何在 Spring Data JPA 中對查詢結果進行排序。 查詢結果使用`ORDER BY`子句或`Sort`對象進行排序。 Spring 是流行的 Java 應用框架，而 Spring Boot 是 Spring 的演進，可以幫助輕松地創建獨立的，生產級的基于 Spring 的應用。 ## Spring Data JPA Spring Data JPA 是傘式 Spring Data 項目的一部分，該項目使實現基于 JPA 的存儲庫更加容易。 Spring Data JPA 使用 JPA 將數據存儲在關系數據庫中。 它可以在運行時從存儲庫接口自動創建存儲庫實現。 ## Spring Data JPA 排序 在 Spring Data JPA 中，查詢結果可以通過兩種方式排序： * 在 JPQL 查詢中使用`ORDER BY`子句 * 將類型為`Sort`的參數添加到查詢方法 ## Spring Boot Data JPA 排序示例 以下應用檢索按升序排序的城市。 ```java pom.xml src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ │ Application.java │ │ ├───controller │ │ │ MyController.java │ │ ├───model │ │ │ City.java │ │ ├───repository │ │ │ CityRepository.java │ │ └───service │ │ CityService.java │ │ ICityService.java │ └───resources │ application.properties │ data-h2.sql │ schema-h2.sql └───test └───java ``` 這是項目結構。 `pom.xml` ```java <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.zetcode</groupId> <artifactId>springbootdatajpasort</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> </properties> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.1.RELEASE</version> </parent> <dependencies> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> ``` 這是 Maven `pom.xml`文件。 `resources/application.properties` ```java spring.main.banner-mode=off spring.datasource.platform=h2 spring.jpa.hibernate.ddl-auto=none ``` 在主屬性文件中，我們使用`spring.main.banner-mode`屬性關閉 Spring Boot 橫幅。 `spring.datasource.platform`設置為`h2`，因此數據庫名稱存在于數據庫初始化腳本中。 由于我們從 SQL 代碼初始化腳本，因此通過將`spring.jpa.hibernate.ddl-auto`設置為`none`可以關閉從實體自動創建表的功能。 `com/zetcode/model/City.java` ```java package com.zetcode.model; import java.util.Objects; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name = "cities") public class City { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String name; private int population; public City() { } public City(String name, int population) { this.name = name; this.population = population; } 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 int getPopulation() { return population; } public void setPopulation(int population) { this.population = population; } @Override public int hashCode() { int hash = 7; hash = 79 * hash + Objects.hashCode(this.id); hash = 79 * hash + Objects.hashCode(this.name); hash = 79 * hash + this.population; return hash; } @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final City other = (City) obj; if (this.population != other.population) { return false; } if (!Objects.equals(this.name, other.name)) { return false; } return Objects.equals(this.id, other.id); } @Override public String toString() { var builder = new StringBuilder(); builder.append("City{id=").append(id).append(", name=") .append(name).append(", population=") .append(population).append("}"); return builder.toString(); } } ``` 這是`City`實體。 `resources/schema-h2.sql` ```java CREATE TABLE cities(id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(255), population INT); ``` 啟動應用時，將執行`schema-h2.sql`腳本。 它創建一個新的數據庫表。 `resources/data-h2.sql` ```java INSERT INTO cities(name, population) VALUES('Bratislava', 432000); INSERT INTO cities(name, population) VALUES('Budapest', 1759000); INSERT INTO cities(name, population) VALUES('Prague', 1280000); INSERT INTO cities(name, population) VALUES('Warsaw', 1748000); INSERT INTO cities(name, population) VALUES('Los Angeles', 3971000); INSERT INTO cities(name, population) VALUES('New York', 8550000); INSERT INTO cities(name, population) VALUES('Edinburgh', 464000); INSERT INTO cities(name, population) VALUES('Suzhou', 4327066); INSERT INTO cities(name, population) VALUES('Zhengzhou', 4122087); INSERT INTO cities(name, population) VALUES('Berlin', 3671000); ``` 之后，執行`data-h2.sql`文件。 它用數據填充表。 `com/zetcode/service/ICityService.java` ```java package com.zetcode.service; import com.zetcode.model.City; import java.util.List; public interface ICityService { List<City> findAllOrderByPopulationAsc(); List<City> findAllOrderByNameAsc(); } ``` `ICityService`包含兩種簽約方法。 `com/zetcode/service/CityService.java` ```java package com.zetcode.service; import com.zetcode.model.City; import com.zetcode.repository.CityRepository; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.domain.Sort; import org.springframework.stereotype.Service; import java.util.List; @Service public class CityService implements ICityService { @Autowired private CityRepository repository; @Override public List<City> findAllOrderByPopulationAsc() { return repository.findAllOrderByPopulationAsc(); } @Override public List<City> findAllOrderByNameAsc() { var sort = new Sort(Sort.Direction.ASC, "name"); return repository.findAllOrderByNameAsc(sort); } } ``` 在這里，我們有兩種排序方法的實現。 ```java @Override public List<City> findAllOrderByNameAsc() { var sort = new Sort(Sort.Direction.ASC, "name"); return repository.findAllOrderByNameAsc(sort); } ``` `Sort`對象按名稱升序對查詢結果進行排序。 `Sort`作為參數傳遞給方法。 `com/zetcode/repository/CityRepository.java` ```java package com.zetcode.repository; import com.zetcode.model.City; import org.springframework.data.domain.Sort; import org.springframework.data.jpa.repository.Query; import org.springframework.data.repository.CrudRepository; import org.springframework.stereotype.Repository; import java.util.List; @Repository public interface CityRepository extends CrudRepository<City, Long> { @Query("FROM City ORDER BY population ASC") List<City> findAllOrderByPopulationAsc(); @Query("FROM City") List<City> findAllOrderByNameAsc(Sort sort); } ``` `CityRepository`有兩種分類方法。 在第一種情況下，我們使用`ORDER BY`子句。 在第二種情況下，我們使用`Sort`對象。 `com/zetcode/controller/MyController.java` ```java package com.zetcode.controller; import com.zetcode.model.City; import com.zetcode.service.ICityService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; import java.util.List; @RestController public class MyController { @Autowired private ICityService cityService; @GetMapping(value = "/cities") public List<City> getCitiesByPopulation() { return cityService.findAllOrderByPopulationAsc(); } @GetMapping(value = "/cities2") public List<City> getCitiesByName() { return cityService.findAllOrderByNameAsc(); } } ``` 控制器為 RESTFul，并以 JSON 格式返回數據。 `com/zetcode/Application.java` ```java package com.zetcode; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); } } ``` `Application`是設置 Spring Boot 應用的入口點。 我們使用`mvn -q spring-boot:run`運行該應用。 ```java $ curl localhost:8080/cities [{"id":1,"name":"Bratislava","population":432000},{"id":7,"name":"Edinburgh","population":464000}, {"id":3,"name":"Prague","population":1280000},{"id":4,"name":"Warsaw","population":1748000}, {"id":2,"name":"Budapest","population":1759000},{"id":10,"name":"Berlin","population":3671000}, {"id":5,"name":"LosAngeles","population":3971000},{"id":9,"name":"Zhengzhou","population":4122087}, {"id":8,"name":"Suzhou","population":4327066},{"id":6,"name":"NewYork","population":8550000}] ``` 在此輸出中，城市按人口按升序排序。 ```java $ curl localhost:8080/cities2 [{"id":10,"name":"Berlin","population":3671000},{"id":1,"name":"Bratislava","population":432000}, {"id":2,"name":"Budapest","population":1759000},{"id":7,"name":"Edinburgh","population":464000}, {"id":5,"name":"LosAngeles","population":3971000},{"id":6,"name":"NewYork","population":8550000}, {"id":3,"name":"Prague","population":1280000},{"id":8,"name":"Suzhou","population":4327066}, {"id":4,"name":"Warsaw","population":1748000},{"id":9,"name":"Zhengzhou","population":4122087}] ``` 在此輸出中，城市按名稱按升序排序。 本教程展示了如何在 Spring Boot Data JPA 中對查詢結果進行排序。 您可能也對相關教程感興趣： [Spring Boot Data JPA `@Query`教程](/springboot/datajpaquery/)， [Spring Boot Data JPA `@NamedQuery`教程](/springboot/datajpanamedquery/)， [Java 教程](/lang/java/)或列出[所有 Spring Boot 教程](/all/#springboot)。