分页技术原理与实现(三)——无刷新的Ajax分页技术
紧接着上篇—分页技术原理与实现(二)——Java+Oracle实现,本篇继续分析分页技术。上篇讲的是分页技术的代码实现，这篇继续分析一下分页技术的效果控制。
上篇已经用代码简单的实现了一个分页。但是我们都看到，代码中每次通过servlet请求取得结果集后，都会转向到一个jsp页面显示结果，这样每次查询页面都会刷新一下，比如查询出现结果集后要查看第三页，页面就会刷新一下。这样页面给人的效果感觉就会有点不舒服，所以我们希望能够在通过条件查询结果集后无论访问哪一页，页面都不会刷新，而只是结果集变化。要解决这个，我想大家很容易就会想到Ajax了。
是啊，这就要请Ajax出山了。当通过查询条件查询到结果集后，以后每次访问任何一页都通过Ajax来访问，使用异步Ajax与Servlet进行交互，将结果查询出来返回给Ajax，这样页面内容因为Ajax返回结果而改变，而页面却不会刷新，这就实现了无刷新的分页技术。
下面我们来看一个简单的无刷新分页实现，代码如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" href="../lib/jquery_pagination/pagination.css" mce_href="lib/jquery_pagination/pagination.css" /> <mce:script type="text/javascript" src="../lib/jquery/jquery.min.js" mce_src="lib/jquery/jquery.min.js"></mce:script> <mce:script type="text/javascript" src="../lib/jquery_pagination/jquery.pagination.js"></mce:script> <mce:script type="text/javascript"><!-- /** * Callback function that displays the content. * * Gets called every time the user clicks on a pagination link. * * @param {int}page_index New Page index * @param {jQuery} jq the container with the pagination links as a jQuery object */ function pageselectCallback(page_index, jq) { var new_content = $('#hiddenresult div.result:eq(' + page_index + ')') .clone(); $('#Searchresult').empty().append(new_content); return false; } function initPagination() { var num_entries = $('#hiddenresult div.result').length; // Create pagination element $("#Pagination").pagination(num_entries, { num_edge_entries : 2, num_display_entries : 8, callback : pageselectCallback, items_per_page : 1 }); } // When the HTML has loaded, call initPagination to paginate the elements $(document).ready(function() { initPagination(); }); // --></mce:script> <mce:style type="text/css"><!-- * { padding: 0; margin: 0; } body { background-color: #fff; margin: 20px; padding: 0; height: 100%; font-family: Arial, Helvetica, sans-serif; } #Searchresult { margin-top: 15px; margin-bottom: 15px; border: solid 1px #eef; padding: 5px; background: #eef; width: 40%; } #Searchresult p { margin-bottom: 1.4em; } --></mce:style><style type="text/css" mce_bogus="1">* { padding: 0; margin: 0; } body { background-color: #fff; margin: 20px; padding: 0; height: 100%; font-family: Arial, Helvetica, sans-serif; } #Searchresult { margin-top: 15px; margin-bottom: 15px; border: solid 1px #eef; padding: 5px; background: #eef; width: 40%; } #Searchresult p { margin-bottom: 1.4em; }</style> <title>Pagination</title> </head> <body> <h4> jQuery Pagination Plugin Demo </h4> <div id="Pagination" class="pagination"> </div> <br style="clear: both;" mce_style="clear: both;" /> <div id="Searchresult"> This content will be replaced when pagination inits. </div> <div id="hiddenresult" style="display: none;" mce_style="display: none;"> <div class="result"> <p> Globally maximize granular "outside the box" thinking vis-a-vis quality niches. Proactively formulate 24/7 results whereas 2.0 catalysts for change. Professionally implement 24/365 niches rather than client-focused users. </p> <p> Competently engineer high-payoff "outside the box" thinking through cross functional benefits. Proactively transition intermandated processes through open-source niches. Progressively engage maintainable innovation and extensible interfaces. </p> </div> <div class="result"> <p> Credibly fabricate e-business models for end-to-end niches. Compellingly disseminate integrated e-markets without ubiquitous services. Credibly create equity invested channels with multidisciplinary human capital. </p> <p> Interactively integrate competitive users rather than fully tested infomediaries. Seamlessly initiate premium functionalities rather than impactful architectures. Rapidiously leverage existing resource-leveling processes via user-centric portals. </p> </div> <div class="result"> <p> Monotonectally initiate unique e-services vis-a-vis client-centric deliverables. Quickly impact parallel opportunities with B2B bandwidth. Synergistically streamline client-focused infrastructures rather than B2C e-commerce. </p> <p> Phosfluorescently fabricate 24/365 e-business through 24/365 total linkage. Completely facilitate high-quality systems without stand-alone strategic theme areas. </p> </div> </div> </body> </html>
这就是一个非常简单的无刷新分页实现，使用了JQuery+ jquery.pagination框架。现在随着框架的流行，尤其是Jquery的流行，使用框架来开发是非常有效的。上面代码原理在代码中已有注释，也可参考Jquery的官方网站：。
现在就可以来开发我们的Ajax无刷新分页实现。基于上面的原理，在响应页码被按下的代码中pageselectCallback()，我们使用一个Ajax异步访问数据库，通过点击的页号将结果集取出后再用异步设置到页面，这样就可以完成了无刷新实现。
页码被按下的响应函数pageselectCallback()修改如下：
这样就可以用异步方式获取结果，用showResponse函数来处理结果了，showResponse函数如下：
function showResponse(request){ var content = request; var root = content.documentElement; var responseNodes = root.getElementsByTagName("root"); var itemList = new Array(); var pageList=new Array(); alert(responseNodes.length); if (responseNodes.length > 0) { var responseNode = responseNodes[0]; var itemNodes = responseNode.getElementsByTagName("data"); for (var i=0; i<itemNodes.length; i++) { var idNodes = itemNodes[i].getElementsByTagName("id"); var nameNodes = itemNodes[i].getElementsByTagName("name"); var sexNodes=itemNodes[i].getElementsByTagName("sex"); var ageNodes=itemNodes[i].getElementsByTagName("age"); if (idNodes.length > 0 && nameNodes.length > 0&&sexNodes.length > 0&& ageNodes.length > 0) { var id=idNodes[0].firstChild.nodeValue; var name = nameNodes[0].firstChild.nodeValue; var sex = sexNodes[0].firstChild.nodeValue; var age=ageNodes[0].firstChild.nodeValue; itemList.push(new Array(id,name, sex,age)); } } var pageNodes = responseNode.getElementsByTagName("pagination"); if (pageNodes.length>0) { var totalNodes = pageNodes[0].getElementsByTagName("total"); var startNodes = pageNodes[0].getElementsByTagName("start"); var endNodes=pageNodes[0].getElementsByTagName("end"); var currentNodes=pageNodes[0].getElementsByTagName("pageno"); if (totalNodes.length > 0 && startNodes.length > 0&&endNodes.length > 0) { var total=totalNodes[0].firstChild.nodeValue; var start = startNodes[0].firstChild.nodeValue; var end = endNodes[0].firstChild.nodeValue; var current=currentNodes[0].firstChild.nodeValue; pageList.push(new Array(total,start,end,current)); } } } showTable(itemList,pageList); }
如上代码就是用来处理通过Ajax异步请求Servlet后返回的XML格式的结果，其中Servlet代码在上篇中。其中itemList、pageList分别是解析返回后生成的用户List和分页导航，这样用户就可以以自己的展现方式展现数据了。
function pageselectCallback(page_index, jq){ var pars="pageNo="+(page_index+1); $.ajax({ type: "POST", url: " UserBasicSearchServlet", cache: false, data: pars, success: showResponse }); return false; }