實(shí)際上分頁(yè)器或者分頁(yè)組件在現(xiàn)實(shí)中都有廣泛著的應(yīng)用，照理來(lái)說(shuō)老衛(wèi)沒(méi)有必要單獨(dú)撰文來(lái)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(yè)器啊之類的插件都不能很好的兼容，百度谷歌無(wú)果，而且 Bootstrap 4 還沒(méi)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(yè)器了，所用到的技術(shù)就是 Spring Data、Thymeleaf 3、Bootstrap 4 。
分頁(yè)器有哪些需求
中國(guó)式報(bào)表從來(lái)都是最復(fù)雜的，隨之衍生而來(lái)的分頁(yè)器要求也是錯(cuò)綜復(fù)雜。本例為求把分頁(yè)器原理告訴給大家，所以，將分頁(yè)組件的抽象為以下通用的內(nèi)容：
- 顯示頁(yè)碼的列表；
- 該列表的第一項(xiàng)是“上一頁(yè)”，最后一項(xiàng)是“下一頁(yè)”；
- 當(dāng)前選中的頁(yè)碼要高亮；
- 當(dāng)當(dāng)前頁(yè)的上一頁(yè)沒(méi)有頁(yè)碼可選時(shí)，則“上一頁(yè)”置為不可點(diǎn)擊的狀態(tài)；
- 當(dāng)當(dāng)前頁(yè)的下一頁(yè)沒(méi)有頁(yè)碼可選時(shí)，則“下一頁(yè)”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(yè)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(kāi)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(yè)器接口，提供了常用的方法，比如：
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List getContent(); // 返回分頁(yè)后的數(shù)據(jù)的列表int getTotalPages(); // 總頁(yè)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(yè)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(yè)面的索引，size 是頁(yè)面的大?。ㄒ豁?yè)最多有多少個(gè)數(shù)據(jù)）。
Spring Data 可以說(shuō)提供了我們前端分頁(yè)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(lái)渲染頁(yè)面。最爽的莫過(guò)于根據(jù)綁定的數(shù)據(jù)列表來(lái)遍歷生成頁(yè)面元素，比如：
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<ul class="pagination" > <!-- 上一頁(yè) --> <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(yè)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(yè) --> <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=${page.number} + 1" aria-label="Next"> <span aria-hidden="true">»</span> </a> </li></ul> |
這個(gè)就是簡(jiǎn)單版本的分頁(yè)器了，可以看到我們的分頁(yè)器的“上一頁(yè)”和“下一頁(yè)”是固定不變的，中間根據(jù) totalPages（總頁(yè)數(shù)）來(lái)動(dòng)態(tài)生成頁(yè)面。同時(shí)，我們根據(jù)是否是當(dāng)前頁(yè)（number + 1）來(lái)設(shè)置樣式是否高亮（active）。“上一頁(yè)”和“下一頁(yè)”是需要做一下判斷的，若當(dāng)前頁(yè)是第一頁(yè)（first）則“上一頁(yè)”不能點(diǎn)擊（disabled）；如果當(dāng)前頁(yè)是最后一頁(yè)（last）則“下一頁(yè)”不能點(diǎn)擊（disabled）。
考慮的再多一點(diǎn)
實(shí)際上，上面版本可以應(yīng)付大多數(shù)的應(yīng)用場(chǎng)景了。但是，可能會(huì)有點(diǎn)不完美，比如，我的頁(yè)數(shù)很多怎么辦？那么我們的分頁(yè)列表可能被拉得很長(zhǎng)了，領(lǐng)導(dǎo)們可能會(huì)不滿意的！絕對(duì)要把這種不滿意的情緒扼殺在搖籃里。
可以看到，假如要做得更加完美，則還需要考慮，當(dāng)頁(yè)數(shù)太多時(shí)，應(yīng)該將某些用省略號(hào)。這就涉及到三種情況了：
- 當(dāng)當(dāng)前頁(yè)頁(yè)碼接近首頁(yè)時(shí)，省略號(hào)在后部出現(xiàn)；
- 當(dāng)當(dāng)前頁(yè)頁(yè)碼接最后頁(yè)時(shí)，省略號(hào)在前部出現(xiàn)；
- 最煩的要屬于，當(dāng)當(dāng)前頁(yè)在中部時(shí)，前部、后部都需要省略號(hào)；
帶省略號(hào)的分頁(yè)器
聰明的工程師們應(yīng)該馬上行動(dòng)起來(lái)，大致的把算法畫了個(gè)草圖：
為求簡(jiǎn)單，我們預(yù)設(shè)頁(yè)碼的列表最多在 7 頁(yè)（你也可以根據(jù)需要來(lái)改），也就是說(shuō)，當(dāng) totalPages（總頁(yè)數(shù)）超過(guò) 7時(shí)，我們才需要考慮省略號(hào)的事情。
- “上一頁(yè)”和“下一頁(yè)”的算法于我們上面的簡(jiǎn)單版本類似，這里就不贅述了。
- 當(dāng)前頁(yè)面頁(yè)碼小于等于4時(shí)，省略號(hào)在列表后部的倒數(shù)第二個(gè)出現(xiàn)；
- 最后一頁(yè)與當(dāng)前頁(yè)面之差小于等于3時(shí)，省略號(hào)在列表前部的第二個(gè)位置出現(xiàn)；
- 其余情況，則當(dāng)前頁(yè)適中處于中間位置，省略號(hào)同時(shí)在列表第二個(gè)位置及倒數(shù)第二個(gè)位置出現(xiàn)。
實(shí)現(xiàn)方式如下：
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<!-- 處理頁(yè)數(shù)大于7 的情況 --><ul class="pagination" data-th-if="${page.totalPages gt 7}" > <!-- 上一頁(yè) --> <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=${page.number} - 1" aria-label="Previous"> <span aria-hidden="true">«</span> </a> </li> <!-- 首頁(yè) --> <li class="page-item" data-th-classappend="${(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(yè)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="${(page.number + 1) le 4}"> <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link"> <span aria-hidden="true">...</span> </a> </li> <!-- 最后一頁(yè)與當(dāng)前頁(yè)面之差，小于等于3 --> <li class="page-item disabled" data-th-if="${(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(yè)與當(dāng)前頁(yè)面之差大于3，且 當(dāng)前頁(yè)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="${((page.number + 1) gt 4) && ((page.totalPages-(page.number + 1)) gt 3 )}"> <a href="javascript:void(0);" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="page-link"> <span aria-hidden="true">...</span> </a> </li> <!-- 最后一頁(yè) --> <li class="page-item" data-th-classappend="${(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(yè) --> <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(kāi)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：
- 是否可以選擇頁(yè)面的最大頁(yè)？
- 是否可以選擇任意頁(yè)面的索引？
等等，尼瑪看來(lái)下表快凌晨1點(diǎn)了。頂不順了，要睡了。各位讀者朋友可以繼續(xù)完善~
最終效果
以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持服務(wù)器之家。
原文鏈接：http://www.importnew.com/24722.html?utm_source=tuicool&utm_medium=referral
