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Spring Data + Thymeleaf 3 + Bootstrap 4 實(shí)現(xiàn)分頁器實(shí)例代碼

更新時(shí)間：2017年05月20日 08:38:51 作者：waylau

本篇文章主要介紹了Spring Data + Thymeleaf 3 + Bootstrap 4 實(shí)現(xiàn)分頁器實(shí)例代碼，非常具有實(shí)用價(jià)值，需要的朋友可以參考下

實(shí)際上分頁器或者分頁組件在現(xiàn)實(shí)中都有廣泛著的應(yīng)用，照理來說老衛(wèi)沒有必要單獨(dú)撰文來提這茬。事實(shí)是，我近期剛好在寫一門關(guān)于Spring Data、Thymeleaf 3、Bootstrap 4 的應(yīng)用課程，所以用了Bootstrap 4的樣式，結(jié)果之前很多例如 Bootstrap 3 的表格、分頁器啊之類的插件都不能很好的兼容，百度谷歌無果，而且 Bootstrap 4 還沒有出穩(wěn)定版本，官網(wǎng)的示例也是少的可憐，最終下決心要自己寫個(gè)分頁器了，所用到的技術(shù)就是 Spring Data、Thymeleaf 3、Bootstrap 4 。

分頁器有哪些需求

中國(guó)式報(bào)表從來都是最復(fù)雜的，隨之衍生而來的分頁器要求也是錯(cuò)綜復(fù)雜。本例為求把分頁器原理告訴給大家，所以，將分頁組件的抽象為以下通用的內(nèi)容：

顯示頁碼的列表；
該列表的第一項(xiàng)是“上一頁”，最后一項(xiàng)是“下一頁”；
當(dāng)前選中的頁碼要高亮；
當(dāng)當(dāng)前頁的上一頁沒有頁碼可選時(shí)，則“上一頁”置為不可點(diǎn)擊的狀態(tài)；
當(dāng)當(dāng)前頁的下一頁沒有頁碼可選時(shí)，則“下一頁”置為不可點(diǎn)擊的狀態(tài)；

我們很容易就能找到一個(gè) Bootstrap 分頁器的設(shè)計(jì)原型，如下圖：

你可以參考 Bootstrap 官網(wǎng)的介紹 http://getbootstrap.com/components/#pagination，但建議你不要直接用上面的樣式，因?yàn)檫@個(gè)樣式是 Bootstrap 3版本的。最后，我找到的了Bootstrap 4 里面的樣式，卻不在官網(wǎng) http://www.quackit.com/bootstrap/bootstrap_4/tutorial/bootstrap_pagination.cfm。感謝 books-collection 項(xiàng)目帶給程序員的開源、免費(fèi)圖書集合！

Spring Data 能做什么

org.springframework.data.domain.Page 是 Spring Data 提供的一個(gè)分頁器接口，提供了常用的方法，比如：

List getContent(); // 返回分頁后的數(shù)據(jù)的列表
int getTotalPages(); // 總頁數(shù)
long getTotalElements(); // 總數(shù)據(jù)量
boolean isFirst(); // 是否是第一個(gè)數(shù)據(jù)；
boolean isLast(); // 是否是最后一個(gè)數(shù)據(jù)；
int getNumber(); // 當(dāng)前頁面索引

構(gòu)造一個(gè) Page，通常需要傳入一個(gè) org.springframework.data.domain.PageRequest.PageRequest對(duì)象，所需參數(shù)為 (int page, int size)，其中 page 就是要請(qǐng)求的頁面的索引，size 是頁面的大小（一頁最多有多少個(gè)數(shù)據(jù)）。

Spring Data 可以說提供了我們前端分頁器所需要的所有元素了。

Thymeleaf 牛刀小試

Thymeleaf 作為模版引擎，其好處就是可以綁定數(shù)據(jù)源，并且根據(jù)數(shù)據(jù)源來渲染頁面。最爽的莫過于根據(jù)綁定的數(shù)據(jù)列表來遍歷生成頁面元素，比如：

<ul class="pagination" >
 <!-- 上一頁 -->
 <li class="page-item" data-th-classappend="*{first} ? 'disabled' : ''">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.number} - 1" aria-label="Previous">
  <span aria-hidden="true">?</span>
 </a>
 </li>
 
 <!-- 迭代生成頁碼 -->
 <li class="page-item" data-th-each="i : ${#numbers.sequence(1, page.totalPages)}" 
 data-th-classappend="${(page.number + 1) eq i} ? 'active' : ''" >
 <a class="page-link" data-th-attr="pageIndex=${i} - 1" href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >
       <span data-th-text="${i}"></span>
    </a>
 </li>
 
 <!-- 下一頁 -->
 <li class="page-item" data-th-classappend="*{last} ? 'disabled' : ''">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.number} + 1" aria-label="Next">
  <span aria-hidden="true">?</span>
 </a>
 </li>
</ul>

這個(gè)就是簡(jiǎn)單版本的分頁器了，可以看到我們的分頁器的“上一頁”和“下一頁”是固定不變的，中間根據(jù) totalPages（總頁數(shù)）來動(dòng)態(tài)生成頁面。同時(shí)，我們根據(jù)是否是當(dāng)前頁（number + 1）來設(shè)置樣式是否高亮（active）。“上一頁”和“下一頁”是需要做一下判斷的，若當(dāng)前頁是第一頁（first）則“上一頁”不能點(diǎn)擊（disabled）；如果當(dāng)前頁是最后一頁（last）則“下一頁”不能點(diǎn)擊（disabled）。

考慮的再多一點(diǎn)

實(shí)際上，上面版本可以應(yīng)付大多數(shù)的應(yīng)用場(chǎng)景了。但是，可能會(huì)有點(diǎn)不完美，比如，我的頁數(shù)很多怎么辦？那么我們的分頁列表可能被拉得很長(zhǎng)了，領(lǐng)導(dǎo)們可能會(huì)不滿意的！絕對(duì)要把這種不滿意的情緒扼殺在搖籃里。

可以看到，假如要做得更加完美，則還需要考慮，當(dāng)頁數(shù)太多時(shí)，應(yīng)該將某些用省略號(hào)。這就涉及到三種情況了：

當(dāng)當(dāng)前頁頁碼接近首頁時(shí)，省略號(hào)在后部出現(xiàn)；
當(dāng)當(dāng)前頁頁碼接最后頁時(shí)，省略號(hào)在前部出現(xiàn)；
最煩的要屬于，當(dāng)當(dāng)前頁在中部時(shí)，前部、后部都需要省略號(hào)；

帶省略號(hào)的分頁器

聰明的工程師們應(yīng)該馬上行動(dòng)起來，大致的把算法畫了個(gè)圖：

為求簡(jiǎn)單，我們預(yù)設(shè)頁碼的列表最多在 7 頁（你也可以根據(jù)需要來改），也就是說，當(dāng) totalPages（總頁數(shù)）超過 7時(shí)，我們才需要考慮省略號(hào)的事情。

“上一頁”和“下一頁”的算法于我們上面的簡(jiǎn)單版本類似，這里就不贅述了。
當(dāng)前頁面頁碼小于等于4時(shí)，省略號(hào)在列表后部的倒數(shù)第二個(gè)出現(xiàn)；
最后一頁與當(dāng)前頁面之差小于等于3時(shí)，省略號(hào)在列表前部的第二個(gè)位置出現(xiàn)；
其余情況，則當(dāng)前頁適中處于中間位置，省略號(hào)同時(shí)在列表第二個(gè)位置及倒數(shù)第二個(gè)位置出現(xiàn)。

實(shí)現(xiàn)方式如下：

<!-- 處理頁數(shù)大于7 的情況 --> 
<ul class="pagination" data-th-if="${page.totalPages gt 7}" >
 <!-- 上一頁 -->
 <li class="page-item" data-th-classappend="*{first} ? 'disabled' : ''">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.number} - 1" aria-label="Previous">
  <span aria-hidden="true">?</span>
 </a>
 </li>
 
 <!-- 首頁 -->
 <li class="page-item" data-th-classappend="${(page.number + 1) eq 1} ? 'active' : ''" >
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=0">1</a>
 </li>
 
 
 <!-- 當(dāng)前頁面小于等于4 -->
 <li class="page-item" data-th-if="${(page.number + 1) le 4}" data-th-each="i : ${#numbers.sequence(2,5)}" 
 data-th-classappend="${(page.number + 1) eq i} ? 'active' : ''" >
 <a class="page-link" href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-th-attr="pageIndex=${i} - 1">
      <span data-th-text="${i}"></span>
    </a>
 </li>

 <li class="page-item disabled" data-th-if="${(page.number + 1) le 4}">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link">
  <span aria-hidden="true">...</span>
 </a>
 </li>
 
 <!-- 最后一頁與當(dāng)前頁面之差，小于等于3 -->
 <li class="page-item disabled" data-th-if="${(page.totalPages-(page.number + 1)) le 3}">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link">
  <span aria-hidden="true">...</span>
 </a>
 </li> 
 <li class="page-item" data-th-if="${(page.totalPages-(page.number + 1)) le 3}" data-th-each="i : ${#numbers.sequence(page.totalPages-4, page.totalPages-1)}" 
 data-th-classappend="${(page.number + 1) eq i} ? 'active' : ''" >
 <a class="page-link" href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-th-attr="pageIndex=${i} - 1">
      <span data-th-text="${i}"></span>
    </a>
 </li>
 
 <!-- 最后一頁與當(dāng)前頁面之差大于3，且 當(dāng)前頁面大于4-->
 
 <li class="page-item disabled" data-th-if="${((page.number + 1) gt 4) && ((page.totalPages-(page.number + 1)) gt 3 )}">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link">
  <span aria-hidden="true">...</span>
 </a>
 </li> 
 <li class="page-item" data-th-if="${((page.number + 1) gt 4) && ((page.totalPages-(page.number + 1)) gt 3 )}" >
  <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.number}">[[${page.number}]]</a>
 </li>
 <li class="page-item active" data-th-if="${((page.number + 1) gt 4) && ((page.totalPages-(page.number + 1)) gt 3 )}">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.number} + 1">[[${page.number + 1}]]</a>
 </li>
 <li class="page-item" data-th-if="${((page.number + 1) gt 4) && ((page.totalPages-(page.number + 1)) gt 3 )}">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.number} + 2">[[${page.number + 2}]]</a>
 </li>
 
 <li class="page-item disabled" data-th-if="${((page.number + 1) gt 4) && ((page.totalPages-(page.number + 1)) gt 3 )}">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link">
  <span aria-hidden="true">...</span>
 </a>
 </li>

 <!-- 最后一頁 -->
 <li class="page-item" data-th-classappend="${(page.number + 1) eq page.totalPages} ? 'active' : ''" >
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.totalPages} - 1">[[${page.totalPages}]]</a>
 </li>

 <!-- 下一頁 -->
 <li class="page-item" data-th-classappend="*{last} ? 'disabled' : ''">
 <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link" data-th-attr="pageIndex=${page.number} + 1" aria-label="Next">
  <span aria-hidden="true">?</span>
 </a>
 </li>
</ul>

還要再考慮的多一點(diǎn)？

當(dāng)然，正如我們開篇所講，中國(guó)式報(bào)表的需求千奇百怪，本文也只是從大部分通用需求出發(fā)，給個(gè)思路，不一定能滿足所有人的需求。如果可能的話，再考慮多一點(diǎn)，比如：