分页

　　分页大家都知道有逻辑分页和物理分页，逻辑分页：即将信息全部查询出来，然后通过代码去进去分页，并不是依赖于SQL。物理分页： 即SQL中采用了limit 关键字来进行分页。小菜鸟使用的一般当然就是物理分页了，limit直接使用多简单。 为什么要写这篇博客呢，一是因为分页也是公司中常用的技术点之一，二是上星期公司中的一个项目中的分页有问题，那个项目是外包出去一段时间然后拿回来的，刚好分页是别人写的，那个代码写的(大家懂得)，只好自己再改一遍。所以想了想还是写篇博客记录下来，以后有类似的问题也可以直接拿来使用。

　　分页中最重要的就是五要素了，我叫它分页五要素，其中包括当前页数(currentPage)，总页数（totalPage）,总记录数(totalResult)，当前页中显示的记录数(showCount)，当前页中显示的数据(list)。 先说说物理分页吧，物理分页采用limit，当然了两种分页各有千秋，在此我就不多说了。limit 2，4 就是从3 开始查询，查询4条数据。因为其是从0开始的，所以是不包含头的。这里主要讲的是逻辑分页，逻辑分页，先查询出所有的数据，然后使用代码将其进行分页操作，话不多说，先上代码

package com.cn.platform.common.page;

import java.util.Map;

public class Page {
    private int showCount = 10; // 每页显示记录数
    private int totalPage; // 总页数
    private int totalResult; // 总记录数
    private int currentPage; // 当前页
    private int currentResult; // 当前记录起始索引
    private boolean entityOrField; // true:需要分页的地方，传入的参数就是Page实体；false:需要分页的地方，传入的参数所代表的实体拥有Page属性
    private String pageStr; // 最终页面显示的底部翻页导航，详细见：getPageStr();

    private String orderColunm;// 排序条件
    private String orderMode;// 排序方式

    private Map<String, Object> queryParam;

    public int getTotalPage() {
        if (totalResult % showCount == 0) {
            if (totalResult == 0) {
                totalPage = 1;
            } else {

                totalPage = totalResult / showCount;
            }
        } else {

            totalPage = totalResult / showCount + 1;
        }
        return totalPage;
    }

    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }

    public int getTotalResult() {
        return totalResult;
    }

    public void setTotalResult(int totalResult) {
        this.totalResult = totalResult;
    }

    public int getCurrentPage() {
        if (currentPage <= 0)
            currentPage = 1;
        if (currentPage > getTotalPage())
            currentPage = getTotalPage();
        return currentPage;
    }

    public void setCurrentPage(int currentPage) {
        this.currentPage = currentPage;
    }

    public String getPageStr() {
        StringBuffer sb = new StringBuffer();
        if (totalResult > 0) {
            sb.append("    <ul>\n");
            if (currentPage == 1) {
                sb.append("    <li class=\"pageinfo\">首页</li>\n");
                sb.append("    <li class=\"pageinfo\">上页</li>\n");
            } else {
                sb.append("    <li><a href=\"#@\" onclick=\"nextPage(1)\">首页</a></li>\n");
                sb.append("    <li><a href=\"#@\" onclick=\"nextPage(" + (currentPage - 1) + ")\">上页</a></li>\n");
            }
            int showTag = 3; // 分页标签显示数量
            int startTag = 1;
            if (currentPage > showTag) {
                startTag = currentPage - 1;
            }
            int endTag = startTag + showTag - 1;
            for (int i = startTag; i <= totalPage && i <= endTag; i++) {
                if (currentPage == i)
                    sb.append("<li class=\"current\">" + i + "</li>\n");
                else
                    sb.append("    <li><a href=\"#@\" onclick=\"nextPage(" + i + ")\">" + i + "</a></li>\n");
            }
            if (currentPage == totalPage) {
                sb.append("    <li class=\"pageinfo\">下页</li>\n");
                sb.append("    <li class=\"pageinfo\">尾页</li>\n");
            } else {
                sb.append("    <li><a href=\"#@\" onclick=\"nextPage(" + (currentPage + 1) + ")\">下页</a></li>\n");
                sb.append("    <li><a href=\"#@\" onclick=\"nextPage(" + totalPage + ")\">尾页</a></li>\n");
            }
            sb.append("    <li class=\"pageinfo\">第" + currentPage + "页</li>\n");
            sb.append("    <li class=\"pageinfo\">共" + totalPage + "页</li>\n");
            sb.append("</ul>\n");
            sb.append("<script type=\"text/javascript\">\n");
            sb.append("function nextPage(page){");
            sb.append("    if(true && document.forms[0]){\n");
            sb.append("        var url = document.forms[0].getAttribute(\"action\");\n");
            sb.append("        if(url.indexOf('?')>-1){url += \"&" + (entityOrField ? "currentPage" : "page.currentPage")
                    + "=\";}\n");
            sb.append("        else{url += \"?" + (entityOrField ? "currentPage" : "page.currentPage") + "=\";}\n");
            sb.append("        document.forms[0].action = url+page;\n");
            sb.append("        document.forms[0].submit();\n");
            sb.append("    }else{\n");
            sb.append("        var url = document.location+'';\n");
            sb.append("        if(url.indexOf('?')>-1){\n");
            sb.append("            if(url.indexOf('currentPage')>-1){\n");
            sb.append("                var reg = /currentPage=\\d*/g;\n");
            sb.append("                url = url.replace(reg,'currentPage=');\n");
            sb.append("            }else{\n");
            sb.append("                url += \"&" + (entityOrField ? "currentPage" : "page.currentPage") + "=\";\n");
            sb.append("            }\n");
            sb.append("        }else{url += \"?" + (entityOrField ? "currentPage" : "page.currentPage") + "=\";}\n");
            sb.append("        document.location = url + page;\n");
            sb.append("    }\n");
            sb.append("}\n");
            sb.append("</script>\n");
        }
        pageStr = sb.toString();
        return pageStr;
    }

    public void setPageStr(String pageStr) {
        this.pageStr = pageStr;
    }

    public int getShowCount() {
        return showCount;
    }

    public void setShowCount(int showCount) {
        this.showCount = showCount;
    }

    public int getCurrentResult() {
        currentResult = (getCurrentPage() - 1) * getShowCount();
        if (currentResult < 0)
            currentResult = 0;
        return currentResult;
    }

    public void setCurrentResult(int currentResult) {
        this.currentResult = currentResult;
    }

    public boolean isEntityOrField() {
        return entityOrField;
    }

    public void setEntityOrField(boolean entityOrField) {
        this.entityOrField = entityOrField;
    }

    public String getOrderColunm() {
        return orderColunm;
    }

    public void setOrderColunm(String orderColunm) {
        this.orderColunm = orderColunm;
    }

    public String getOrderMode() {
        return orderMode;
    }

    public void setOrderMode(String orderMode) {
        this.orderMode = orderMode;
    }

    public Map<String, Object> getQueryParam() {
        return queryParam;
    }

    public void setQueryParam(Map<String, Object> queryParam) {
        this.queryParam = queryParam;
    }
    
    public void setPageMessage(Page page,String orderColunm,String orderMode) {
        int totalPage = 0;
        if (page.getTotalResult() != 0 ) {
            if (page.getTotalResult()%page.getShowCount() > 0) {
                totalPage = page.getTotalResult()/page.getShowCount() + 1;
            }else{
                totalPage = page.getTotalResult()/page.getShowCount();
            }
            page.setTotalPage(totalPage);
        }
        page.setOrderColunm(orderColunm);
        page.setOrderMode(orderMode);
    }

}

 

  

/**
 * 分页链接HTML
 */
function splitPageHtml2(divId, formId, totalRow, pageSize, pageNumber, totalPages, isSelectPage, isSelectSize, orderColunm, orderMode){
    
    var splitStr = '<div class="sub_pages centers jushang">';
    splitStr += '<div class="lefts">每页 <b>'+pageSize+'</b> 条 共 <b>'+totalRow+'</b>条记录 页码：<b>'+pageNumber+'</b> / <b>'+totalPages+'</b></div>';
    splitStr+='<div class="rights">';
    
    if (pageNumber == 1 || totalPages == 0) {
        //首页
        splitStr += '<span class="sub_pages_item radiuss4"><i class="icon-double-angle-left left_sub right_sub"><a href="javascript:void(0)"></a></i></span>';
    } else {
        //上一页
        splitStr += '<span class="sub_pages_item radiuss4" onclick="javascript:splitPageLink(\''+divId+'\', \''+formId+'\', 1);"><i class="icon-double-angle-left left_sub right_sub"></i></span>';
    }
    
    if (pageNumber == 1 || totalPages == 0) {
        //尾页
        splitStr += '<span class="sub_pages_item radiuss4"><i class="icon-angle-left left_sub right_sub"><a href="javascript:void(0)"></a></i></span>';
    } else {
        //下一页
        splitStr += '<span class="sub_pages_item radiuss4" onclick="javascript:splitPageLink(\''+divId+'\', \''+formId+'\', ' + (pageNumber - 1) + ');"><i class="icon-angle-left left_sub right_sub"></i></span>';
    }
    
    for (var i = 1; i <= totalPages; i++) {
        if (i == 2 && pageNumber - 4 > 1) {
//            splitStr += '<li><a href="javascript:void(0)">...</a></li>';
            splitStr += '...';
            i = pageNumber - 4;
        } else if (i == pageNumber + 4 && pageNumber + 4 < totalPages) {
//            splitStr += '<li><a href="javascript:void(0)">...</a></li>';
            splitStr += '...';
            i = totalPages - 1;
        } else {
            if (pageNumber == i) {
//                splitStr += '<li class="active"><a href="javascript:void(0)" style="color: #272727; font-size: 14px; text-decoration: none;">' + pageNumber + '</a></li>';
                splitStr += '<span class="sub_pages_item sub_pages_item_num radiuss4 spi_on"><a href="javascript:void(0)">' + pageNumber + '</a></span>';
            } else {
//                splitStr += '<li><a href="javascript:splitPageLink(\''+divId+'\', \''+formId+'\', ' + i + ');" style="color: #898989; font-size: 14px;">';
//                splitStr += i;
//                splitStr += '</a></li>';
                splitStr += '<span class="sub_pages_item sub_pages_item_num radiuss4" onclick="javascript:splitPageLink(\''+divId+'\', \''+formId+'\', ' + i + ');"><a href="javascript:splitPageLink(\''+divId+'\', \''+formId+'\', ' + i + ');">';
                splitStr += i;
                splitStr += '</a></span>';
            }
        }
    }
    
    if (pageNumber == totalPages || totalPages == 0) {
        splitStr += '<span class="sub_pages_item radiuss4"><i class="icon-angle-right left_sub right_sub"></i></span>';
    } else {
        splitStr += '<span class="sub_pages_item radiuss4" onclick="javascript:splitPageLink(\''+divId+'\', \''+formId+'\', ' + (pageNumber + 1) + ');"><i class="icon-angle-right left_sub right_sub"></i></span>';
    }
    
    
    if (pageNumber == totalPages || totalPages == 0) {
        splitStr += '<span class="sub_pages_item radiuss4"><i class="icon-double-angle-right left_sub right_sub"></i></span>';
    } else {
        splitStr += '<span class="sub_pages_item radiuss4" onclick="javascript:splitPageLink(\''+divId+'\', \''+formId+'\', ' + totalPages + ');"><i class="icon-double-angle-right left_sub right_sub"></i></span>';
    }
    
    if(isSelectPage == true){
        splitStr += '  <select name="currentPage" onChange="splitPageLink(\''+divId+'\', \''+formId+'\', this.value);" style="width: 100px; height:25px;">';
        for (var i = 1; i <= totalPages; i++) {
            if (i == pageNumber) {
                splitStr += '<option selected value="' + i + '">跳转到第' + i +'页</option>';
            } else {
                splitStr += '<option value="' + i + '">跳转到第' + i+ '页</option>';
            }
        }
        if(totalPages == 0){
            splitStr += '<option value="0">无跳转数据</option>';
        }
        splitStr += '</select>';
        splitStr += '  ';
    }else{
        splitStr += '<input type="hidden" name="currentPage"/>';
    }
    
    /*if(isSelectSize == true){
        splitStr += '<select name="showCount" onChange="splitPageLink(\''+divId+'\', \''+formId+'\', 1);" style="width: 80px; height:25px;">';
        
        var optionStr = '<option value="10">每页10条</option>';
        optionStr += '<option value="20">每页20条</option>';
        optionStr += '<option value="40">每页40条</option>';
        optionStr += '<option value="80">每页80条</option>';
        optionStr += '<option value="100">每页100条</option>';
        optionStr += '<option value="200">每页200条</option>';
        optionStr = optionStr.replace('"' + pageSize + '"', '"' + pageSize + '" selected="selected"');
        
        splitStr += optionStr;
        
        splitStr += '</select>';
    }else{
        splitStr += '<input type="hidden" name="showCount">';
    }
    */
    
    splitStr += '  共<strong>' + totalRow + '</strong>条记录';
    
    splitStr += '';
    
    splitStr += '<input type="hidden" name="orderColunm" value="'+orderColunm+'"/>';
    splitStr += '<input type="hidden" name="orderMode" value="'+orderMode+'"/>';
    
    splitStr+='</div>';
    splitStr+='<div class="cleans"></div>';
    splitStr+='</div>';
    
    return splitStr;
}

/**
 * 分页链接处理
 */
function splitPageLink(divId, formId, toPage){
    //alert($("#" + formId + " select[name=pageNumber]").attr("name"));//input[name=pageNumber]
    $("#" + formId + " select[name=currentPage],input[name=currentPage] ").val(toPage);
    var url = $("#url").val();
    var totalResult = $("#totalResult").val();
    var basePath = $("#basePath").val();
    var result = basePath+url+"?currentPage="+ toPage + "&totalResult=" + totalResult;
    ajaxContent(result);  // 封装的ajax提交到后台的方法
}

　　分页其实也不难，不管是逻辑分页还是物理分页，最主要的是分页5要素之间的计算和转换，上面代码中都有详细的阐述。其中showCount是已知的，currentResult和list是查询出来的，currentPage是前台传递到后台的，而totalPage是根据currentResult和currentPage计算出来的，所以说相当于5要素都是已知的。