欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识！
您现在的位置是： 首页

在Spring Boot中使用Spring-data-jpa实现分页查询

程序员文章站 2024-03-18 13:31:34
...

在我们平时的工作中，查询列表在我们的系统中基本随处可见，那么我们如何使用jpa进行多条件查询以及查询列表分页呢？下面我将介绍两种多条件查询方式。

1、引入起步依赖   

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

2、对thymeleaf和jpa进行配置

    打开application.yml，添加以下参数，以下配置在之前的文章中介绍过，此处不做过多说明

spring:
  thymeleaf:
    cache: true
    check-template-location: true
    content-type: text/html
    enabled: true
    encoding: utf-8
    mode: HTML5
    prefix: classpath:/templates/
    suffix: .html
    excluded-view-names:
    template-resolver-order:
  datasource:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/restful?useUnicode=true&characterEncoding=UTF-8&useSSL=false
      username: root
      password: root
      initialize: true
  init-db: true
  jpa:
      database: mysql
      show-sql: true
      hibernate:
        ddl-auto: update
        naming:
          strategy: org.hibernate.cfg.ImprovedNamingStrategy

3、编写实体Bean

@Entity
@Table(name="book")
public class Book {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", updatable = false)
    private Long id;

    @Column(nullable = false,name = "name")
    private String name;

    @Column(nullable = false,name = "isbn")
    private String isbn;

    @Column(nullable = false,name = "author")
    private String author;

    public Book (String name,String isbn,String author){
        this.name = name;
        this.isbn = isbn;
        this.author = author;
    }
    public Book(){

    }
    //此处省去get、set方法
}

public class BookQuery {
    private String name;
    private String isbn;
    private String author;
    //此处省去get、set方法
}

4、编写Repository接口

@Repository("bookRepository")
public interface BookRepository extends JpaRepository<Book,Long> 
        ,JpaSpecificationExecutor<Book> {
}

    此处继承了两个接口，后续会介绍为何会继承这两个接口

5、抽象service层

    首先抽象出接口

public interface BookQueryService {
    Page<Book> findBookNoCriteria(Integer page,Integer size);
    Page<Book> findBookCriteria(Integer page,Integer size,BookQuery bookQuery);
}

    实现接口

@Service(value="bookQueryService")
public class BookQueryServiceImpl implements BookQueryService {
    @Resource
    BookRepository bookRepository;
    @Override
    public Page<Book> findBookNoCriteria(Integer page,Integer size) {
        Pageable pageable = new PageRequest(page, size, Sort.Direction.ASC, "id");
        return bookRepository.findAll(pageable);
    }

    @Override
    public Page<Book> findBookCriteria(Integer page, Integer size, final BookQuery bookQuery) {
        Pageable pageable = new PageRequest(page, size, Sort.Direction.ASC, "id");
        Page<Book> bookPage = bookRepository.findAll(new Specification<Book>(){
            @Override
            public Predicate toPredicate(Root<Book> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) {
                List<Predicate> list = new ArrayList<Predicate>();
                if(null!=bookQuery.getName()&&!"".equals(bookQuery.getName())){
                    list.add(criteriaBuilder.equal(root.get("name").as(String.class), bookQuery.getName()));
                }
                if(null!=bookQuery.getIsbn()&&!"".equals(bookQuery.getIsbn())){
                    list.add(criteriaBuilder.equal(root.get("isbn").as(String.class), bookQuery.getIsbn()));
                }
                if(null!=bookQuery.getAuthor()&&!"".equals(bookQuery.getAuthor())){
                    list.add(criteriaBuilder.equal(root.get("author").as(String.class), bookQuery.getAuthor()));
                }
                Predicate[] p = new Predicate[list.size()];
                return criteriaBuilder.and(list.toArray(p));
            }
        },pageable);
        return bookPage;
    }
}

    此处我定义了两个接口，findBookNoCriteria是不带查询条件的，findBookCriteria是带查询条件的。在此处介绍一下上面提到的自定义Repository继承的两个接口，如果你的查询列表是没有查询条件，只是列表展示和分页，只需继承JpaRepository接口即可，但是如果你的查询列表是带有多个查询条件的话则需要继承JpaSpecificationExecutor接口，这个接口里面定义的多条件查询的方法。当然不管继承哪个接口，当你做分页查询时，都是需要调用findAll方法的，这个方法是jap定义好的分页查询方法。

    findBookCriteria方法也可以使用以下方法实现，大家可以自行选择

 @Override
    public Page<Book> findBookCriteria(Integer page, Integer size, final BookQuery bookQuery) {
        Pageable pageable = new PageRequest(page, size, Sort.Direction.ASC, "id");
        Page<Book> bookPage = bookRepository.findAll(new Specification<Book>(){
            @Override
            public Predicate toPredicate(Root<Book> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) {
                Predicate p1 = criteriaBuilder.equal(root.get("name").as(String.class), bookQuery.getName());
                Predicate p2 = criteriaBuilder.equal(root.get("isbn").as(String.class), bookQuery.getIsbn());
                Predicate p3 = criteriaBuilder.equal(root.get("author").as(String.class), bookQuery.getAuthor());
                query.where(criteriaBuilder.and(p1,p2,p3));
                return query.getRestriction();
            }
        },pageable);
        return bookPage;
    }

6、编写Controller

    针对有查询条件和无查询条件，我们分别编写一个Controller，默认每页显示5条，如下

@Controller
@RequestMapping(value = "/queryBook")
public class BookController {
    @Autowired
    BookQueryService bookQueryService;

    @RequestMapping("/findBookNoQuery")
    public String findBookNoQuery(ModelMap modelMap,@RequestParam(value = "page", defaultValue = "0") Integer page,
                        @RequestParam(value = "size", defaultValue = "5") Integer size){
        Page<Book> datas = bookQueryService.findBookNoCriteria(page, size);
        modelMap.addAttribute("datas", datas);
        return "index1";
    }

    @RequestMapping(value = "/findBookQuery",method = {RequestMethod.GET,RequestMethod.POST})
    public String findBookQuery(ModelMap modelMap, @RequestParam(value = "page", defaultValue = "0") Integer page,
                                @RequestParam(value = "size", defaultValue = "5") Integer size, BookQuery bookQuery){
        Page<Book> datas = bookQueryService.findBookCriteria(page, size,bookQuery);
        modelMap.addAttribute("datas", datas);
        return "index2";
    }
}

7、编写页面

    首先我们编写一个通用的分页页面，新建一个叫page.html的页面

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:th="http://www.thymeleaf.org"
      xmlns:layout="http://www.ultraq.net.nz/thymeleaf/layout"
      layout:decorator="page">
<body>
<div th:fragment="pager">
    <div class="text-right" th:with="baseUrl=${#httpServletRequest.getRequestURL().toString()},pars=${#httpServletRequest.getQueryString() eq null ? '' : new String(#httpServletRequest.getQueryString().getBytes('iso8859-1'), 'UTF-8')}">
        <ul style="margin:0px;" class="pagination" th:with="newPar=${new java.lang.String(pars eq null ? '' : pars).replace('page='+(datas.number), '')},
                                                curTmpUrl=${baseUrl+'?'+newPar},
                                                curUrl=${curTmpUrl.endsWith('&amp;') ? curTmpUrl.substring(0, curTmpUrl.length()-1):curTmpUrl}" >
            <!--<li th:text="${pars}"></li>-->

            <li><a href="#" th:href="@{${curUrl}(page=0)}">首页</a></li>
            <li th:if="${datas.hasPrevious()}"><a href="#" th:href="@{${curUrl}(page=${datas.number-1})}">上一页</a></li>

            <!--总页数小于等于10-->
            <div th:if="${(datas.totalPages le 10) and (datas.totalPages gt 0)}" th:remove="tag">
                <div th:each="pg : ${#numbers.sequence(0, datas.totalPages - 1)}" th:remove="tag">
                        <span th:if="${pg eq datas.getNumber()}" th:remove="tag">
                            <li class="active"><span class="current_page line_height" th:text="${pg+1}">${pageNumber}</span></li>
                        </span>
                    <span th:unless="${pg eq datas.getNumber()}" th:remove="tag">
                            <li><a href="#" th:href="@{${curUrl}(page=${pg})}" th:text="${pg+1}"></a></li>
                        </span>
                </div>
            </div>

            <!-- 总数数大于10时 -->
            <div th:if="${datas.totalPages gt 10}" th:remove="tag">
                <li th:if="${datas.number-2 ge 0}"><a href="#" th:href="@{${curUrl}(page=${datas.number}-2)}" th:text="${datas.number-1}"></a></li>
                <li th:if="${datas.number-1 ge 0}"><a href="#" th:href="@{${curUrl}(page=${datas.number}-1)}" th:text="${datas.number}"></a></li>
                <li class="active"><span class="current_page line_height" th:text="${datas.number+1}"></span></li>
                <li th:if="${datas.number+1 lt datas.totalPages}"><a href="#" th:href="@{${curUrl}(page=${datas.number}+1)}" th:text="${datas.number+2}"></a></li>
                <li th:if="${datas.number+2 lt datas.totalPages}"><a href="#" th:href="@{${curUrl}(page=${datas.number}+2)}" th:text="${datas.number+3}"></a></li>
            </div>


            <li th:if="${datas.hasNext()}"><a href="#" th:href="@{${curUrl}(page=${datas.number+1})}">下一页</a></li>
            <!--<li><a href="#" th:href="@{${curUrl}(page=${datas.totalPages-1})}">尾页</a></li>-->
            <li><a href="#" th:href="${datas.totalPages le 0 ? curUrl+'page=0':curUrl+'&amp;page='+(datas.totalPages-1)}">尾页</a></li>
            <li><span th:utext="'共'+${datas.totalPages}+'页 / '+${datas.totalElements}+' 条'"></span></li>
        </ul>
    </div>
</div>
</body>
</html>

    针对无查询条件的接口，创建一个名为index1.html的页面并引入之前写好的分页页面，如下

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8"/>
    <title>Title</title>
    <script type="text/javascript" th:src="@{/jquery-1.12.3.min.js}"></script>
    <script type="text/javascript" th:src="@{/bootstrap/js/bootstrap.min.js}"></script>
    <link type="text/css" rel="stylesheet" th:href="@{/bootstrap/css/bootstrap-theme.min.css}"/>
    <link type="text/css" rel="stylesheet" th:href="@{/bootstrap/css/bootstrap.css}"/>
</head>
<body>
    <table class="table table-hover">
        <thead>
        <tr>
            <th>ID</th>
            <th>name</th>
            <th>isbn</th>
            <th>author</th>
        </tr>
        </thead>
        <tbody>
        <tr th:each="obj : ${datas}">
            <td th:text="${obj.id}">${obj.id}</td>
            <td th:text="${obj.name}">${obj.name}</td>
            <td th:text="${obj.isbn}">${obj.isbn}</td>
            <td th:text="${obj.name}">${obj.author}</td>
        </tr>
        </tbody>
    </table>
        <div th:include="page :: pager" th:remove="tag"></div>
</body>
</html>

     针对有查询条件的接口，创建一个名为index2.html的页面并引入之前写好的分页页面，如下

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8"/>
    <title>Title</title>
    <script type="text/javascript" th:src="@{/jquery-1.12.3.min.js}"></script>
    <script type="text/javascript" th:src="@{/bootstrap/js/bootstrap.min.js}"></script>
    <link type="text/css" rel="stylesheet" th:href="@{/bootstrap/css/bootstrap-theme.min.css}"/>
    <link type="text/css" rel="stylesheet" th:href="@{/bootstrap/css/bootstrap.css}"/>
</head>
<body>
<form th:action="@{/queryBook/findBookQuery}" th:object="${bookQuery}" th:method="get">
    <div class="form-group">
        <label class="col-sm-2 control-label" >name</label>
        <div class="col-sm-4">
            <input type="text" class="form-control" id="name" placeholder="请输入名称" th:field="*{name}"/>
        </div>
        <label class="col-sm-2 control-label">isbn</label>
        <div class="col-sm-4">
            <input type="text" class="form-control" id="isbn" placeholder="请输ISBN" th:field="*{isbn}"/>
        </div>
    </div>
    <div class="form-group">
        <label class="col-sm-2 control-label" >author</label>
        <div class="col-sm-4">
            <input type="text" class="form-control" id="author" placeholder="请输author" th:field="*{author}"/>
        </div>
        <div class="col-sm-4">
            <button class="btn btn-default" type="submit" placeholder="查询">查询</button>
        </div>
    </div>
</form>
    <table class="table table-hover">
        <thead>
        <tr>
            <th>ID</th>
            <th>name</th>
            <th>isbn</th>
            <th>author</th>
        </tr>
        </thead>
        <tbody>
        <tr th:each="obj : ${datas}">
            <td th:text="${obj.id}">${obj.id}</td>
            <td th:text="${obj.name}">${obj.name}</td>
            <td th:text="${obj.isbn}">${obj.isbn}</td>
            <td th:text="${obj.name}">${obj.author}</td>
        </tr>
        </tbody>
    </table>
        <div th:include="page :: pager" th:remove="tag"></div>
</body>
</html>

    ok！代码都已经完成，我们将项目启动起来，看一下效果。大家可以往数据库中批量插入一些数据，访问http://localhost:8080/queryBook/findBookNoQuery，显示如下页面

在Spring Boot中使用Spring-data-jpa实现分页查询

访问http://localhost:8080/queryBook/findBookQuery，显示页面如下，可以输入查询条件进行带条件的分页查询：

在Spring Boot中使用Spring-data-jpa实现分页查询

    ok！以上便是一个简单的jap分页查询功能的实现。

博文转自：https://my.oschina.net/wangxincj/blog/820670

相关标签： 分页

上一篇： C语言_扫雷

下一篇： C语言——中国象棋（无图形化界面）

推荐阅读