在Spring Boot中使用Spring-data-jpa实现分页查询

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="https://my.oschina.net/wangxincj/blog/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 = "https://my.oschina.net/queryBook")
public class BookController {
@Autowired
BookQueryService bookQueryService;

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

@RequestMapping(value = "https://my.oschina.net/findBookQuery",method = {RequestMethod.GET,RequestMethod.POST})
public String findBookQuery(ModelMap modelMap, @RequestParam(value = "https://my.oschina.net/wangxincj/blog/page", defaultValue = "https://my.oschina.net/wangxincj/blog/0") Integer page,
@RequestParam(value = "https://my.oschina.net/wangxincj/blog/size", defaultValue = "https://my.oschina.net/wangxincj/blog/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=${curTmpUrl.endsWith('&') ? curTmpUrl.substring(0, curTmpUrl.length()-1):curTmpUrl}" >
<!--<li th:text="${pars}"></li>-->

<li><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=0)}">首页</a></li>
<li th:if="${datas.hasPrevious()}"><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=${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="${pg eq datas.getNumber()}" th:remove="tag">
<li><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${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="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=${datas.number}-2)}" th:text="${datas.number-1}"></a></li>
<li th:if="${datas.number-1 ge 0}"><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=${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="${datas.number+1 lt datas.totalPages}"><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=${datas.number}+1)}" th:text="${datas.number+2}"></a></li>
<li th:if="${datas.number+2 lt datas.totalPages}"><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=${datas.number}+2)}" th:text="${datas.number+3}"></a></li>
</div>

<li th:if="${datas.hasNext()}"><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=${datas.number+1})}">下一页</a></li>
<!--<li><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/@{${curUrl}(page=${datas.totalPages-1})}">尾页</a></li>-->
<li><a href="https://my.oschina.net/wangxincj/blog/#" th:href="https://my.oschina.net/wangxincj/blog/${datas.totalPages le 0 ? curUrl+'page=0':curUrl+'&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="https://my.oschina.net/wangxincj/blog/@{/jquery-1.12.3.min.js}"></script>
<script type="text/javascript" th:src="https://my.oschina.net/wangxincj/blog/@{/bootstrap/js/bootstrap.min.js}"></script>
<link type="text/css" rel="stylesheet" th:href="https://my.oschina.net/wangxincj/blog/@{/bootstrap/css/bootstrap-theme.min.css}"/>
<link type="text/css" rel="stylesheet" th:href="https://my.oschina.net/wangxincj/blog/@{/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="https://my.oschina.net/wangxincj/blog/@{/jquery-1.12.3.min.js}"></script>
<script type="text/javascript" th:src="https://my.oschina.net/wangxincj/blog/@{/bootstrap/js/bootstrap.min.js}"></script>
<link type="text/css" rel="stylesheet" th:href="https://my.oschina.net/wangxincj/blog/@{/bootstrap/css/bootstrap-theme.min.css}"/>
<link type="text/css" rel="stylesheet" th:href="https://my.oschina.net/wangxincj/blog/@{/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



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：



ok！以上便是一个简单的jap分页查询功能的实现。

转自：http://www.07net01.com/2017/01/1772868.html