Spring Data JPA实现排序与分页查询超详细流程讲解

下面我来详细讲解一下“Spring Data JPA实现排序与分页查询超详细流程讲解”的完整攻略。本教程共包含以下五个步骤：

1. 引入依赖

在pom.xml文件中加入以下依赖：

<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>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.72</version>
</dependency>

1. 创建实体类和DAO层

创建实体类Book和对应的DAO层BookRepository：

Book实体类：

@Entity
@Table(name = "tb_book")
public class Book {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String title;

    private String author;

    private Double price;

    @Column(name = "publication_date")
    private Date publicationDate;

    //getters and setters

}

BookRepository接口：

public interface BookRepository extends JpaRepository<Book, Long> {

    Page<Book> findByTitleContaining(String title, Pageable pageable);

}

1. 创建控制器

创建一个RestController，提供两个接口分别实现分页和排序查询：

@RestController
public class BookController {

    @Autowired
    private BookRepository bookRepository;

    @GetMapping("/books")
    public ResponseEntity<Page<Book>> findBooksByPage(@RequestParam(defaultValue = "0") Integer page,
                                                       @RequestParam(defaultValue = "5") Integer size,
                                                       @RequestParam(required = false) String title) {
        Pageable pageable = PageRequest.of(page, size, Sort.Direction.ASC,"id");
        Page<Book> books = bookRepository.findByTitleContaining(title, pageable);
        return ResponseEntity.ok(books);
    }

    @GetMapping("/books/sort")
    public ResponseEntity<List<Book>> findBooksBySort() {
        Sort sort = Sort.by(Sort.Direction.DESC, "price");
        List<Book> books = bookRepository.findAll(sort);
        return ResponseEntity.ok(books);
    }

}

其中，findBooksByPage方法实现分页查询，findBooksBySort方法实现排序查询。

1. 测试接口

使用REST client等工具测试接口，例如分页查询：

http://localhost:8080/books?page=1&size=10&title=java

返回结果为：

{
    "content": [
        {
            "id": 2,
            "title": "Head First Java",
            "author": "Bert Bates, Kathy Sierra",
            "price": 79.0,
            "publicationDate": "2018-01-01"
        }
    ],
    "pageable": {
        "sort": {
            "sorted": true,
            "unsorted": false,
            "empty": false
        },
        "pageSize": 10,
        "pageNumber": 1,
        "offset": 10,
        "paged": true,
        "unpaged": false
    },
    "last": false,
    "totalPages": 1,
    "totalElements": 1,
    "sort": {
        "sorted": true,
        "unsorted": false,
        "empty": false
    },
    "first": false,
    "numberOfElements": 1,
    "size": 10,
    "number": 1,
    "empty": false
}

1. 结束语

至此，我们介绍了使用Spring Data JPA实现排序与分页查询的完整攻略，希望对你有所帮助。

示例2：从前往后的正序排列

@GetMapping("/books/sort")
public ResponseEntity<List<Book>> findBooksBySort() {
    Sort sort = Sort.by(Sort.Direction.ASC, "publicationDate");
    List<Book> books = bookRepository.findAll(sort);
    return ResponseEntity.ok(books);
}

测试接口：

http://localhost:8080/books/sort

返回结果为：

[
    {
        "id": 2,
        "title": "Head First Java",
        "author": "Bert Bates, Kathy Sierra",
        "price": 79.0,
        "publicationDate": "2018-01-01"
    },
    {
        "id": 1,
        "title": "Head First Design Patterns",
        "author": "Eric Freeman, Elisabeth Robson",
        "price": 59.0,
        "publicationDate": "2019-01-01"
    }
]

以上就是两个示例的具体流程，希望对你有所帮助。