一、通用分页

将上一次查询请求再发一次，只不过改变了页码。

二、具体思路： 1、补全servlet 2、页面展示9 ’3、分页重要参数（page、rows、是否分页、上一次请求、上一次的表单参数） 4、自定义分页标签

创建一个通用分页： 1.创建分页工具类PageBean类：

package util; import java.util.HashMap; import java.util.Map; import javax.servlet.http.HttpServletRequest; /** * 分页工具类 * */ public class PageBean { private int page = 1;// 页码 private int rows = 10;// 页大小 private int total = 0;// 总记录数 private boolean pagination = true;// 是否分页 private Map<String, String[]> paramMap = new HashMap<>();//保留上一次的参数 private String url;//保留上一次的请求地址 public void setRequest(HttpServletRequest req) {//pageBean 初始化方法 this.setPage(req.getParameter("page")); this.setRows(req.getParameter("rows")); this.setPagination(req.getParameter("pagination")); // getRequestURL获取到浏览器请求的全路径 this.setUrl(req.getRequestURL().toString()); // getParameterMap可以获取到一次url请求所携带的所有参数 this.setParamMap(req.getParameterMap()); } public void setPagination(String pagination) { if (StringUtils.isNotBlank(pagination)) { this.setPagination(!"false".equals(pagination));//是否分页 } } public void setRows(String rows) {//改变 rows属性 页 if (StringUtils.isNotBlank(rows)) this.setRows(Integer.valueOf(rows));//每页多少天数据 } public void setPage(String page) { if (StringUtils.isNotBlank(page)) { this.setPage(Integer.valueOf(page));//多少页 } } public PageBean() { super(); } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public Map<String, String[]> getParamMap() { return paramMap; } public void setParamMap(Map<String, String[]> paramMap) { this.paramMap = paramMap; } public int getPage() { return page; } public void setPage(int page) { this.page = page; } public int getRows() { return rows; } public void setRows(int rows) { this.rows = rows; } public int getTotal() { return total; } public void setTotal(int total) { this.total = total; } public void setTotal(String total) { this.total = Integer.parseInt(total); } public boolean isPagination() { return pagination; } public void setPagination(boolean pagination) { this.pagination = pagination; } /** * 获得起始记录的下标 * * @return */ public int getStartIndex() { return (this.page - 1) * this.rows; } @Override public String toString() { return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]"; } /** * 获取到总页数 * @return */ public int getMaxPage() { return this.total % this.rows == 0 ? this.total / this.rows : (this.total / this.rows) + 1; } /** * 获取下一页页码 * @return */ public int getNextPage() { return this.page < this.getMaxPage() ? this.page+1 : this.page; } /** * 获取上一页页码 * @return */ public int getPreviousPage() { return this.page > 1 ? this.page-1 : this.page; }}

pageTag类：

解决代码的重复利用

package com.pyc.tag; import java.io.IOException; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import javax.servlet.jsp.JspException; import javax.servlet.jsp.JspWriter; import javax.servlet.jsp.tagext.BodyTagSupport; import util.PageBean; public class PageTag extends BodyTagSupport { private static final long serialVersionUID = -6356274451220112552L; private PageBean pageBean; public PageBean getPageBean() { return pageBean; } public void setPageBean(PageBean pageBean) { this.pageBean = pageBean; } @Override public int doStartTag() throws JspException { JspWriter out = pageContext.getOut(); try { out.print(toHTML()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return SKIP_BODY; } private String toHTML() { StringBuilder sb=new StringBuilder(); // 拼接下一次分页请求所提交的分页表单 sb.append("<form id='pageBeanForm' action='"+pageBean.getUrl()+"' method='post'>"); sb.append("<input type='hidden' name='page'>"); Map<String, String []> paMap = pageBean.getPaMap(); if(paMap != null && paMap.size()>0) { Set<Entry<String, String[]>> entrySet = paMap.entrySet(); for (Entry<String, String[]> entry : entrySet) { for(String value : entry.getValue()){ sb.append("<input type='hidden' name='"+entry.getKey()+"' value='"+value+"'>"); } } } sb.append("</form>"); // 拼接分页条 sb.append("<div style='text-align: right; font-size: 12px;'>"); sb.append(" 每页"+pageBean.getRows()+"条，共"+pageBean.getTotal()+"条，第"+pageBean.getPage()+"页，共"+pageBean.getMaxPage()+"页  <a"); sb.append(" href='javascript:gotoPage(1)'>首页</a>  <a"); sb.append(" href='javascript:gotoPage("+pageBean.getPreviouPage()+")'>上一页</a>  <a"); sb.append(" href='javascript:gotoPage("+pageBean.getNextPage()+")'>下一页</a>  <a"); sb.append(" href='javascript:gotoPage("+pageBean.getMaxPage()+")'>尾页</a>  <input type='text'"); sb.append(" id='skipPage'"); sb.append(" style='text-align: center; font-size: 12px; width: 50px;'>  <a"); sb.append(" href='javascript:skipPage()'>Go</a>"); sb.append("</div>"); // 拼接分页JavaScript代码 sb.append("<script type='text/javascript'>"); sb.append(" function gotoPage(page) {"); sb.append(" document.getElementById('pageBeanForm').page.value = page;"); sb.append(" document.getElementById('pageBeanForm').submit();"); sb.append(" }"); sb.append(" function skipPage() {"); sb.append(" var page = document.getElementById('skipPage').value;"); sb.append(" if(!page || isNaN(page) || parseInt(page)<1 || parseInt(page)>"+pageBean.getMaxPage()+"){"); sb.append(" alert('请输入1~N的数字');"); sb.append(" return;"); sb.append(" }"); sb.append(" gotoPage(page);"); sb.append(" }"); sb.append("</script>"); return sb.toString(); } }

配置 tld 文件

<?xml version="1.0" encoding="UTF-8" ?> <taglib xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd" version="2.0"> <description>pyc 1.1 core library</description> <display-name>pyc core</display-name> <tlib-version>1.1</tlib-version> <short-name>c</short-name> <uri>/pyc</uri> <tag> <name>page</name> <tag-class>com.pyc.tag.PageTag</tag-class> <body-content>JSP</body-content> <attribute> <name>pageBean</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib>

BookServlet类

package web; import java.io.IOException; import java.util.List; import java.util.Map; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import dao.BookDao; import entity.Book; import util.PageBean; public class BookServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String bname = req.getParameter("bname");//也没传来查询书籍的值 Book book =new Book(); book.setBname(bname); PageBean pageBean = new PageBean(); pageBean.setPagination(true);//设置要不要分页 默认为true Map<String, String[]> parameterMap = req.getParameterMap(); String url = req.getRequestURL().toString(); try { List<Book> list = new BookDao().list(book, pageBean); req.setAttribute("bookList", list); req.getRequestDispatcher("/bookList.jsp").forward(req, resp); } catch (Exception e) { e.printStackTrace(); } } }

web.xml： 配置servlet

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <display-name>pagebean</display-name> <filter> <filter-name>encodingFiter</filter-name> <filter-class>com.util.EncodingFiter</filter-class> </filter> <filter-mapping> <filter-name>encodingFiter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <servlet> <servlet-name>bookServlet</servlet-name> <servlet-class>com.web.BookServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>bookServlet</servlet-name> <url-pattern>/bookServlet</url-pattern> </servlet-mapping> </web-app>

Jsp代码： 显示

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <%@ taglib uri="/pyc" prefix="p"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Insert title here</title> </head> <body> <h2>小说目录</h2> <br> <form action="${pageContext.request.contextPath}/bookServlet" method="post"> <!--用户设置查询 一页20条记录 --> <!-- <input type="hidden" name="rows" value="20"/> --> <!--用户设置不分页 --> <!-- <input type="hidden" name="pagination" value="false"/> --> 书名：<input type="text" name="bname"> <input type="submit" value="确定"> </form> <table border="1" width="100%"> <tr> <td>编号</td> <td>名称</td> <td>价格</td> </tr> <c:forEach items="${bookList}" var="b"> <tr> <td>${b.bid }</td> <td>${b.bname }</td> <td>${b.price }</td> </tr> </c:forEach> </table> </body> <h:page pageBean="${pagebean}"></h:page> </html>