目前较常用的分页实现办法有两种：
1.每次翻页都修改SQL，向SQL传入相关参数去数据库实时查出该页的数据并显示。
2.查出数据库某张表的全部数据，再通过在业务逻辑里面进行处理去取得某些数据并显示。
对于数据量并不大的简单的管理系统而言，第一种实现方法相对来说容易使用较少的代码实现分页这一功能，本文也正是为大家介绍这种方法:
代码片段：
1，Page.java
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package com.cm.contract.common; import org.apache.commons.lang.StringUtils; import org.apache.commons.lang.builder.ToStringBuilder; /**分页类 * @author FENGWEI * @date 2016-5-23 */public class Page implements java.io.Serializable{ private static final long serialVersionUID = 1L; //前一页 private Boolean hasPrePage; //后一页 private Boolean hasNextPage; //每页显示多少条:默认20条 private Long everyPage = 20L; //总页数 private Long totalPage; //当前第多少页:默认第1页 private Long currentPage = 1L; //开始下标 private Long beginIndex; //结束下标 private Long endinIndex; //总共多少条 private Long totalCount; //排序列名 private String sortName; //排序状态 private String sortState; //排序信息 private String sortInfo; //是否排序 private Boolean sort = false; private String defaultInfo = " "; public String getDefaultInfo() { return defaultInfo; } public void setDefaultInfo(String defaultInfo) { this.defaultInfo = defaultInfo; } public String getSortInfo() { return sortInfo; } public void setSortInfo(String sortInfo) { this.sortInfo = sortInfo; } public String getSortName() { return sortName; } public void setSortName(String sortName) { setPageSortState(sortName); } public String getSortState() { return sortState; } public void setSortState(String sortState) { this.sortState = sortState; } public Page() { } /** * 常用,用于计算分页 * */ public Page(Long totalRecords){ this.totalCount = totalRecords; setTotalPage(getTotalPage(totalRecords)); } /** * 设置每页显示多少条时使用 * */ public Page(Long everyPage,Long totalRecords){ this.everyPage = everyPage; this.totalCount = totalRecords; setTotalPage(getTotalPage(totalRecords)); } /** * @param state 状态码 * @param value 到第多少页或者设置每页显示多少条或者为排序列名 */ public void pageState(int index,String value) { sort = false; switch (index) { case 0 :setEveryPage(Long.parseLong(value));break; case 1 :first();break; case 2: previous();break; case 3: next();break; case 4: last();break; case 5: sort = true;sort(value);break; case 6 ://到指定第多少页 setCurrentPage(Long.parseLong(value)); break; } } /** * 最前一页 */ private void first() { currentPage = 1L; } private void previous() { currentPage--; } private void next() { currentPage++; } private void last() { currentPage = totalPage; } private void sort(String sortName) { //设置排序状态 setPageSortState(sortName); } /** * 计算总页数 * */ private Long getTotalPage(Long totalRecords) { Long totalPage = 0L; everyPage = everyPage == null ? 10L : everyPage; if (totalRecords % everyPage == 0) totalPage = totalRecords / everyPage; else { totalPage = totalRecords / everyPage + 1; } return totalPage; } public Long getBeginIndex() { this.beginIndex = (currentPage - 1) * everyPage; return this.beginIndex; } public void setBeginIndex(Long beginIndex) { this.beginIndex = beginIndex; } public Long getCurrentPage() { this.currentPage = currentPage == 0 ? 1 : currentPage; return this.currentPage; } public void setCurrentPage(Long currentPage) { if(0 == currentPage){ currentPage = 1L; } this.currentPage = currentPage; } public Long getEveryPage() { this.everyPage = everyPage == 0 ? 10 : everyPage; return this.everyPage; } public void setEveryPage(Long everyPage) { this.everyPage = everyPage; } public Boolean getHasNextPage() { this.hasNextPage = (currentPage != totalPage) && (totalPage != 0); return this.hasNextPage; } public void setHasNextPage(Boolean hasNextPage) { this.hasNextPage = hasNextPage; } public Boolean getHasPrePage() { this.hasPrePage = currentPage != 1; return this.hasPrePage; } public void setHasPrePage(Boolean hasPrePage) { this.hasPrePage = hasPrePage; } public Long getTotalPage() { return this.totalPage; } public void setTotalPage(Long totalPage) { if(this.currentPage > totalPage){ this.currentPage = totalPage; } this.totalPage = totalPage; } public Long getTotalCount() { return this.totalCount; } public void setTotalCount(Long totalCount) { setTotalPage(getTotalPage(totalCount)); this.totalCount = totalCount; } @Override public String toString() { return ToStringBuilder.reflectionToString(this); } /** * 设置排序状态 * */ private void setPageSortState(String newPageSortName){ //判断之前的排序字段是否为空 if(StringUtils.isEmpty(sortName)){ //默认排序为升序 this.sortState = PageUtil.ASC; this.sortInfo = PageUtil.PAGE_ASC; }else{ if(StringUtils.equalsIgnoreCase(newPageSortName, sortName)){ //判断sortState排序状态值 if(StringUtils.equalsIgnoreCase(sortState, PageUtil.ASC)){ this.sortState = PageUtil.DESC; this.sortInfo = PageUtil.PAGE_DESC; }else{ this.sortState = PageUtil.ASC; this.sortInfo = PageUtil.PAGE_ASC; } }else{ //默认 this.sortState = PageUtil.ASC; this.sortInfo = PageUtil.PAGE_ASC; } } sortName = newPageSortName.toLowerCase(); } public Boolean isSort() { return sort; } public void setSort(Boolean sort) { this.sort = sort; } public Long getEndinIndex() { this.endinIndex = (currentPage) * everyPage; return endinIndex; } public void setEndinIndex(Long endinIndex) { this.endinIndex = endinIndex; } } |
2.PageState.java
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package com.cm.contract.common; import org.apache.commons.lang.StringUtils; /**分页状态类 * @author FENGWEI * @date 2016-5-23 */public enum PageState { /** * 设置每页显示多少条 * */ SETPAGE, /** * 首页 * */ FIRST, /** * 向前一页 * */ PREVIOUS, /** * 向后一页 * */ NEXT, /** * 末页 * */ LAST, /** * 排序 * */ SORT, /** * 到第多少页 * */ GOPAGE; /** * @param value 索引名称 * @return 返回索引下标 */ public static int getOrdinal(String value) { int index = -1; if (StringUtils.isEmpty(value)) { return index; } String newValue = StringUtils.trim(value).toUpperCase(); try { index = valueOf(newValue).ordinal(); } catch (IllegalArgumentException e) {} return index; } } |
3.PageUtil.java
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/** * 分页工具类 * @author FENGWEI * @date 2016-5-23 */public class PageUtil { public static final String ASC = "asc"; public static final String DESC = "desc"; public static final String PAGE_DESC = "↓"; public static final String PAGE_ASC = "↑"; public static final String PAGE_NULL = " "; public static final String SESSION_PAGE_KEY = "page"; /** * 初始化分页类 * @param initPageSql 未分页的查询SQL * @param totalCount 总行数 * @param index 分页状态 * @param value 只有在设置每页显示多少条时,值不会NULL,其它为NULL */ public static Page inintPage(Long totalCount,Integer index,String value,Page sessionPage){ Page page = null; if(index < 0){ page = new Page(totalCount); }else{ /**每页显示多少条*/ Long everPage = null == value ? 10 : Long.parseLong(value); /**获取Session中的分页类,方便保存页面分页状态*/ page = sessionPage; page.setEveryPage(everPage); page.setTotalCount(totalCount); } return page; } /** * 当页点击：首页,前一页,后一页,末页,排序,到第多少页时进行分页操作 * @param index 分页状态 * @param value 排序字段名或者到第多少页 */ public static Page execPage(int index,String value,Page sessionPage){ Page page = sessionPage; /**调用方法进行分页计算*/ page.pageState(index,value); return page; } } |
4.DefaultController.java 此部分可以灵活使用
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package com.cm.contract.common; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import org.springframework.web.bind.annotation.ModelAttribute; /** * 提取公用的request和response Title:DefaultController Descrption: * * @author FENGWEI * @date 2016-5-6下午3:30:32 */public class DefaultController { /** * oracel的三层分页语句 子类在展现数据前,进行分页计算! * * @param querySql * 查询的SQL语句,未进行分页 * @param totalCount * 根据查询SQL获取的总条数 * @param columnNameDescOrAsc * 列名+排序方式 : ID DESC or ASC */ protected Page executePage(HttpServletRequest request, Long totalCount) { if (null == totalCount) { totalCount = 0L; } /** 页面状态,这个状态是分页自带的,与业务无关 */ String pageAction = request.getParameter("pageAction"); String value = request.getParameter("pageKey"); /** 获取下标判断分页状态 */ int index = PageState.getOrdinal(pageAction); Page page = null; /** * index < 1 只有二种状态 1 当首次调用时,分页状态类中没有值为 NULL 返回 -1 2 当页面设置每页显示多少条: * index=0,当每页显示多少条时,分页类要重新计算 * */ Page sessionPage = getPage(request); if (index < 1) { page = PageUtil.inintPage(totalCount, index, value, sessionPage); } else { page = PageUtil.execPage(index, value, sessionPage); } setSession(request, page); return page; } private Page getPage(HttpServletRequest request) { Page page = (Page) request.getSession().getAttribute( PageUtil.SESSION_PAGE_KEY); if (page == null) { page = new Page(); } return page; } private void setSession(HttpServletRequest request, Page page) { request.getSession().setAttribute(PageUtil.SESSION_PAGE_KEY, page); } } |
使用方法：
5,Controller.java
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/** * model 添加的分页条件 * executePage 方法写在工具类中 * @param model */@Controllerpublic class CMLogController extends DefaultController { @RequestMapping("index.do") public ModelAndView userInto(ModelMap model, String username) { nameStr = username; model.addAttribute("username", nameStr); // 分页数 Long totalCount = logService.pageCounts(model); // 分页显示 Page page = executePage(request, totalCount); if (page.isSort()) { model.put("orderName", page.getSortName()); model.put("descAsc", page.getSortState()); } else { model.put("orderName", "logtime"); model.put("descAsc", "desc"); } model.put("startIndex", page.getBeginIndex()); model.put("endIndex", page.getEndinIndex()); ModelAndView mv = new ModelAndView(); // 分页查询 logList = logService.pageList(model); mv.addObject("logList", logList); mv.setViewName("/jsp/log"); return mv; }} |
6.maybatis中几条查询语句
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//分页查询 <select id="pageList" parameterType="map" resultMap="BaseResultMap"> select ttt.* from(select tt.*,rownum rn from(select * from CM_LOG <where> <if test="username != null and username != ''"> <!-- 特别提醒一下， $只是字符串拼接， 所以要特别小心sql注入问题。 在开发时使用: $,方便调试sql,发布时使用: # --> and username like '%${username}%' </if> <if test="type != null and type != ''"> <!-- 特别提醒一下， $只是字符串拼接， 所以要特别小心sql注入问题。 在开发时使用: $,方便调试sql,发布时使用: # --> AND TYPE = #{type,jdbcType=VARCHAR} </if> </where> order by ${orderName} ${descAsc} )tt)ttt <where> <if test="startIndex != null and startIndex != ''"> rn > ${startIndex} </if> <if test="endIndex != null and endIndex != ''"> <![CDATA[ and rn <= ${endIndex} ]]> </if> </where> </select> // 分页数 <select id="pageCounts" parameterType="map" resultType="long"> select count(*) from CM_LOG <where> <if test="username != null and username != ''"> and username like '%${username}%' </if> </where> </select> |
7.前台页面index.jsp
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//只需在页面布局添加该div //username 为条件 // <jsp:param name="url" value="/log/index.do?"/> 不带条件的方式 问号必须存在 <body > <div align="right" style="height: 20"> <jsp:include page="/jsp/page.jsp"> <jsp:param name="url" value="/log/index.do?username=${username }"/> </jsp:include> </div> </body > |
8，引用的Page.jsp
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<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <c:set var="page" value="${sessionScope.page}" /> <c:set var="path" value="${pageContext.request.contextPath}" /> <c:set var="url" value="${param.url}" /> <c:set var="urlParams" value="${param.urlParams}" /> <c:set var="pathurl" value="${path}/${url}" /> <tr> <td colspan="5"> ${urlParams } 共${page.totalCount}条记录 共${page.totalPage}页 每页显示${page.everyPage}条 当前第${page.currentPage}页 <c:choose> <c:when test="${page.hasPrePage eq false}"> <<首页 <上页 </c:when> <c:otherwise> <a href="${pathurl}&pageAction=first${urlParams}"><<首页 </a> <a href="${pathurl}&pageAction=previous${urlParams}" /><上一页</a> </c:otherwise> </c:choose> || <c:choose> <c:when test="${page.hasNextPage eq false}"> 下页> 尾页>> </c:when> <c:otherwise> <a href="${pathurl}&pageAction=next${urlParams}">下一页> </a> <a href="${pathurl}&pageAction=last${urlParams}">末页>></a> </c:otherwise> </c:choose> <SELECT name="indexChange" id="indexChange" onchange="getCurrentPage(this.value);"> <c:forEach var="index" begin="1" end="${page.totalPage}" step="1"> <option value="${index}" ${page.currentPage eq index ? "selected" : ""}> 第${index}页 </option> </c:forEach> </SELECT> 每页显示:<select name="everyPage" id="everyPage" onchange="setEveryPage(this.value);"> <c:forEach var="pageCount" begin="5" end="${page.totalCount}" step="5"> <option value="${pageCount}" ${page.everyPage eq pageCount ? "selected" : ""}> ${pageCount}条 </option> </c:forEach> </select> </td> </tr> <div style='display: none'> <a class=listlink id="indexPageHref" href='#'></a> </div> <script> function getCurrentPage(index){ var a = document.getElementById("indexPageHref"); a.href = '${pathurl}&pageAction=gopage&pageKey='+index+'${urlParams}'; a.setAttribute("onclick",''); a.click("return false"); } function setEveryPage(everyPage){ var a = document.getElementById("indexPageHref"); var currentPage = document.getElementById('indexChange').value; a.href = '${pathurl}&pageAction=setpage&pageKey='+everyPage+'${urlParams}'; a.setAttribute("onclick",''); a.click("return false"); } function sortPage(sortName){ var a = document.getElementById("indexPageHref"); a.href = '${pathurl}&pageAction=sort&pageKey='+sortName+'${urlParams}'; a.setAttribute("onclick",''); a.click("return false"); } </script> |
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：http://blog.csdn.net/fiangasdre/article/details/51741456
