通用分页（下）

最新推荐文章于 2023-06-29 01:57:54 发布

electronic老倒霉蛋

最新推荐文章于 2023-06-29 01:57:54 发布

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本文链接：https://blog.youkuaiyun.com/hhhhhhhhzsw/article/details/106455285

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这篇博客详细介绍了如何利用Servlet配置web.xml，创建.tld文件，编写page标签助手类，并在JSP页面中调用自定义标签来实现通用分页功能。通过这些步骤，开发者可以在后续项目中便捷地复用此分页解决方案。

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通用分页

接上一次的博客

servlet

package com.zhangsiwen.test.action;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zhangsiwen.test.dao.StudentDao;
import com.zhangsiwen.test.entity.Student;
import com.zhangsiwen.test.util.PageBean;

public class StudentServlet 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 {
		//获取参数
		Student stu = new Student();
		StudentDao  studao = new StudentDao();
		stu.setSname(req.getParameter("sname"));
		
		//初始化分页
		PageBean pageBean = new PageBean();
		pageBean.setRequest(req);
		req.setAttribute("pageBean", pageBean);
		//后台分页查询
		List<Student> student= studao.find(stu,pageBean);
		req.setAttribute("student", student);
		//跳转界面
		req.getRequestDispatcher("/studentList.jsp").forward(req, resp);
	
	}
}

配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>J2EE_09</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <!--配置处理字符编码的监听  -->
  <filter>
  	<filter-name>EncodingFiter</filter-name>
  	<filter-class>com.zhangsiwen.test.util.EncodingFiter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>EncodingFiter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <!-- 配置studentServlet -->
  <servlet>
  	<servlet-name>studentServlet</servlet-name>
  	<servlet-class>com.zhangsiwen.test.action.StudentServlet</servlet-class>
  </servlet>
  <!--映射Servlet  -->
  <servlet-mapping>
   <servlet-name>studentServlet</servlet-name>
   <url-pattern>/studentAction.action</url-pattern>
  </servlet-mapping>
</web-app>

写一个.tld文件

<!DOCTYPE taglib
  PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
   "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<!-- 标签库描述符 -->
<taglib xmlns="http://java.sun.com/JSP/TagLibraryDescriptor">
	<tlib-version>1.0</tlib-version>
	<jsp-version>1.2</jsp-version>
	<short-name>Simple Tags</short-name>
	<uri>/zhangsiwen</uri>
	<!-- empty标签 -->
	
	<tag>
		<name>page</name>
		<tag-class>com.zhangsiwen.test.tag.PageTag</tag-class>
		<body-content>jsp</body-content>
		<attribute>
			<name>pageBean</name>
			<required>true</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
	</tag>
</taglib>

page的标签助手类

package com.zhangsiwen.test.tag;

import java.lang.reflect.InvocationTargetException;
import java.util.Map;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;


import com.zhangsiwen.test.util.PageBean;

public class PageTag extends BodyTagSupport{

	private static final long serialVersionUID = 1L;
	private PageBean pageBean;
	public PageBean getPageBean() {
		return pageBean;
	}
	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}
	
	@Override
	public int doStartTag() throws JspException {
		try {
			JspWriter out= this.pageContext.getOut();
			out.println(toHtml());
			return SKIP_BODY;
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
		
	}
	
	public String toHtml() throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
		StringBuffer sb=new StringBuffer();
		//防止pagebean空指针异常
		if(null==pageBean||!pageBean.isPagination()) {
			return sb.toString();
		}
		//分页按钮
		sb.append("<div style=\"text-align: center;font-size: 18px\">\r\n" + 
				" 		当前第"+pageBean.getPage()+"页&nbsp;&nbsp; 共"+pageBean.getMaxPage()+"页&nbsp;&nbsp; 共"+pageBean.getTotal()+"条&nbsp;&nbsp;\r\n" + 
				" 		<a href='javascript:doForward(1)'>首页</a>&nbsp;\r\n" + 
				" 		<a href='javascript:doForward("+pageBean.getPreviousPage()+")'>上一页</a>&nbsp;\r\n" + 
				" 		<a href='javascript:doForward("+pageBean.getNextPage()+")'>下一页</a>&nbsp;\r\n" + 
				" 		<a href='javascript:doForward("+pageBean.getMaxPage()+")'>尾页</a>\r\n" + 
				" 		<input id='numTxt' type='text' style='width:50px'>\r\n" + 
				" 		<a href='javascript:doSkip()'>GO</a>\r\n" + 
				" 	</div>");
		
		//分页隐藏域表单 专门用来传递数据的
		sb.append("<form id='pageForm' action='"+this.pageBean.getUrl()+"' method='post'>");
		sb.append("<input type='hidden' name='page'>");
		//从map集合中获取参数
		Map<String,String[]> parameterMap= pageBean.getParameterMap();
		//遍历集合
		for(Map.Entry<String,String[]> entry:parameterMap.entrySet()) {
			String name=entry.getKey();
			String[] value=entry.getValue();
			if("page".equals(name)) {//将上一次的页面抛掉
				continue;//退出循环进入下一个循环
			}
			//遍历数组
			for (int i = 0; i < value.length; i++) {
				sb.append("<input='hidden' name='"+name+"' value='"+value[i]+"'>");
			}
		}
		sb.append("</form>");
		//动态拼接js
		sb.append("<script type='text/javascript'>");
		sb.append("function doForward(page){");
		sb.append(" var f=document.getElementById('pageForm');");
		sb.append(" f.page.value=page;");
		sb.append(" f.submit();");
		sb.append("}");
		sb.append("");
		sb.append("function doSkip(){");
		sb.append(" var num=document.getElementById('numTxt').value;");
		sb.append(" if(!num||isNaN(num)||!/^[0-9]+$/.test(num)||parseInt(num)<=0||parseInt(num)>'"+pageBean.getMaxPage()+"'){");
		sb.append(" alert('请输入1-"+pageBean.getMaxPage()+"之间的整数');");
		sb.append("}");
		sb.append(" doForward(num);");
		sb.append("}");
		sb.append("</script>");
		return sb.toString();
	}
	
}

在jsp页面中调用自定义标签

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <%@taglib prefix="z" uri="/zhangsiwen" %>
<!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>
 <script type="text/javascript">
	function doForward(page){
		var f=document.getElementById('pageForm');
		f.page.value=page;
		f.submit();
	}
	
	function doSkip(){
		var num=document.getElementById('numTxt').value;
		if(!num||isNaN(num)||!/^[0-9]+$/.test(num)||parseInt(num)<=0||parseInt(num)>6){
			alert("请输入1-6之间的整数");
		}
		doForward(num);
	}
	
</script>
</head>
<body>
 <h1>学生查询  <%= System.currentTimeMillis() %>  </h1>
 	<form  action="studentAction.action" method="post">
 		姓名：<input type="text" name="sname">
 		<input type="submit" value="查询">
 	</form>
 	<table border="1px" width="100%"> 
 		<tr>
 		 	<td>学号</td>
 		 	<td>姓名</td>
 		 	<td>年龄</td>
 		 	<td>备注</td>
 		 	<td>操作</td>
 		</tr>
 		<c:forEach items="${student}" var="s" >
 		<tr>
 		 	<td>${s.sid }</td>
 		 	<td>${s.sname }</td>
 		 	<td>${s.age }</td>
 		 	<td>${s.remark }</td>
 		 	<td>操作</td>
 		</tr>
 		</c:forEach>
 	</table>
 	<z:page pageBean="${pageBean }"></z:page>
</body>
</html>

运行结果：
在这里插入图片描述
总结：
我们在写了一遍通用分页之后，在之后需要使用到的时候就可以拿来使用。