通用分页核心思路：
将上一次查询请求再发一次，只是当前页变了而已。
首页 1 2 3 4 … 100 末页 跳转
MySQL分页：select * from 表 limit 3,3
每页显示记录数 自己设置
当前页 来自前端
总页数 总记录数%每页显示记录数==0?总记录数/每页显示记录数:总记录数/每页显示记录数+1
总记录数 数据库统计count()
每页起始记录数 =（当前页-1）*每页显示记录数+1
总共101条记录，每页显示10条
第一页： 1-10
第二页： 11-20
第三页： 21-30
每页结尾记录数 =当前页*每页显示记录数
1、通用的查询方法代码实现
导入jar包
commons-beanutils-1.8.0.jar commons-logging.jar jstl-1.2.jar mysql-connector-java-5.1.44-bin.jar standard-1.1.2.jar
连接数据库之前查看自己的用户名、密码、数据库名是否正确
isOracle：false isSQLServer：false isMysql：true 数据库连接(关闭)成功
#mysql driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/db_book?useUnicode=true&characterEncoding=UTF-8 user=root pwd=root
BookServlet.java
package com.huang.web; import java.io.IOException; import java.sql.SQLException; 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 com.huang.dao.BookDao; import com.huang.entity.Book; import com.huang.util.PageBean; public class BookServlet extends HttpServlet { private static final long serialVersionUID = 2331970325281408992L; private BookDao bookDao=new BookDao(); @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String bname=req.getParameter("bname"); // bname=new String(bname.getBytes("ISO-8859-1"),"UTF-8"); Book book=new Book(); book.setBname(bname); // Map<String, String[]> parameterMap=req.getParameterMap(); // StringBuffer url=req.getRequestURL(); PageBean pagebean=new PageBean(); try { pagebean.setRequest(req); List<Book> list=this.bookDao.list(book, pagebean); req.setAttribute("bookList", list); req.setAttribute("pageBean", pagebean); req.getRequestDispatcher("/bookList.jsp").forward(req, resp); } catch (InstantiationException | IllegalAccessException | SQLException e) { e.printStackTrace(); } } }
bookList.jsp
<%@ 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="/huang" prefix="z"%> <!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="${pageContext.request.contextPath}/bookServlet.action" method="post"> 书名：<input type="text" name="bname"> <input type="submit" value="确定"> <!-- <input type="hidden" name="pagination" value="false"> <input type="hidden" name="rows" value="20"> --> </form> <table border="1" width="100%"> <tr> <td>编号</td> <td>名称</td> <td>价格</td> </tr> <c:forEach items="${bookList }" var="b"> <tr> <td>${b.bid }</td> <td>${b.bname }</td> <td>${b.price }</td> </tr> </c:forEach> </table> <z:page pageBean="${pageBean }"></z:page> </body> </html>
PageBean.java
package com.huang.util; import java.util.HashMap; import java.util.Map; import javax.servlet.http.HttpServletRequest; 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[]> paMap=new HashMap<>(); private String url; public void setRequest(HttpServletRequest req) { //保存上一次请求所携带的参数 this.setPaMap(req.getParameterMap()); this.setUrl(req.getRequestURI().toString()); // 在jsp页面来控制是否分页 this.setPagination(req.getParameter("pagination")); // 在jsp页面 控制一页展示多少条 this.setRows(req.getParameter("rows")); this.setPage(req.getParameter("page")); } public void setPage(String page) { this.page=StringUtils.isNotBlank(page) ? Integer.valueOf(page) : this.page; } public void setPagination(String pagination) { this.pagination=StringUtils.isNotBlank(pagination) ? !"false".equals(pagination) : this.pagination; } public void setRows(String rows) { this.rows=StringUtils.isNotBlank(rows) ? Integer.valueOf(rows) : this.rows; } public Map<String, String[]> getPaMap() { return paMap; } public void setPaMap(Map<String, String[]> paMap) { this.paMap = paMap; } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public PageBean() { super(); } 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 + "]"; } /** * 获取最大的页码数 * @return */ public int getMaxpage() { return this.total % this.rows==0 ? this.total/this.rows : this.total/this.rows+1; } /** * 获取下一页 * @return */ public int getNextpage() { return this.page< this.getMaxpage() ? this.page+1 : this.page; } /** * 获取上一页 */ public int getPreviousPage() { return this.page > 1 ? this.page-1 : this.page; } }
Web.xml
<?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>T226_pagebean</display-name> <filter> <filter-name>encodingFiter</filter-name> <filter-class>com.huang.util.EncodingFiter</filter-class> </filter> <filter-mapping> <filter-name>encodingFiter</filter-name> <servlet-name> *.action</servlet-name> </filter-mapping> <servlet> <servlet-name>bookServlet</servlet-name> <servlet-class>com.huang.web.BookServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>bookServlet</servlet-name> <url-pattern>/bookServlet.action</url-pattern> </servlet-mapping> </web-app>
z.tld
<?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>huang 1.1 core library</description> <display-name>huang core</display-name> <tlib-version>1.1</tlib-version> <short-name>c</short-name> <uri>/huang</uri> <tag> <!--库中的标签（类似c:set c:out的定义）--> <name>page</name> <!-- 是标签运行具体代码，也就是助手类，下面填写的是助手类的全路径名 --> <tag-class>com.huang.tag.PageTag</tag-class> <body-content>JSP</body-content> <attribute> <!-- 该标签的属性 --> <name>pageBean</name> <!-- 该属性是否必填 --> <required>true</required> <!-- 是否支持表达式 --> <rtexprvalue>true</rtexprvalue> </attribute> </tag> </taglib>
PageTag.java
package com.huang.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 com.huang.util.PageBean; public class PageTag extends BodyTagSupport { private static final long serialVersionUID = -7819663757698266331L; 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) { e.printStackTrace(); } return super.doStartTag(); } private String toHTML() { StringBuilder sb=new StringBuilder(); // 拼接下一次发送请求所要提交的隐藏的form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) { // 上一次请求可能携带页码name=page的参数，但是该参数在前面已经单独赋值 // 为什么要单独赋值呢？因为上一次请求是第一页的数据，下一次可能是第二页， // 因为这前后请求page对应的值是不一样的，需要单独赋值 if("page".equals(entry.getKey())) { for (String val : entry.getValue()) { sb.append("<input type='hidden' name='"+entry.getKey()+"' value='"+val+"'>"); } } } } 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.getPreviousPage()+")'>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; 50px;'> <a"); sb.append("href='javascript:skipPage()'>Go</a>"); sb.append("</div>"); // 拼接分页所需要的js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)>maxPage){"); 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(); } }