Filter 将动态页面化为静态

最新推荐文章于 2024-03-22 13:13:15 发布

若节

最新推荐文章于 2024-03-22 13:13:15 发布

阅读量329

点赞数

CC 4.0 BY-SA版权

分类专栏： java javaweb Servlet JSP 文章标签：过滤器

本文链接：https://blog.youkuaiyun.com/qq_33665647/article/details/53900342

java 同时被 3 个专栏收录

167 篇文章

订阅专栏

javaweb

61 篇文章

订阅专栏

Servlet

31 篇文章

订阅专栏

本文介绍了一种通过拦截器将动态页面转化为静态页面的技术方案，该方案能够显著提高页面加载速度，尤其适用于数据更新频率较低的场景。文章详细展示了如何使用Java Servlet过滤器和自定义响应对象来实现这一目标。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

虽然页面是动态的，要从数据库里取数据，但很多数据往往不经常改变，这些界面就可以做成静态的，可以极大提高效率。

主要思路就是：原本把数据从jsp翻译成servlet，然后打印给浏览器，但现在直接把response的反馈给浏览器的，直接放进html文件中，下次访问这个页面，只需要把请求转向 html 文件即可。

要修改Response，写一个修改Response成自己写的类，一个拦截器，拦截特定需要静态化的页面。

StaticFilter.java

package com.filter;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class StaticFilter implements Filter {

	FilterConfig config=null;
	
	public void destroy() {
		
	}

	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request=(HttpServletRequest) req;
		HttpServletResponse response=(HttpServletResponse) resp;
		ServletContext context=config.getServletContext();
		Map<String,String>map=(Map<String, String>) context.getAttribute("map");
		if(map==null)
		   map=new HashMap<String,String>();
		String category=request.getParameter("category");
		String key=category+".html";

		String path = map.get(key);
		if(path==null||path.trim().isEmpty())
		{
			map.put(key, "/html/"+key);
			context.setAttribute("map", map);
			path = map.get(key);
			StaticResponse staticResp=new StaticResponse(response,request.getRealPath("\\")+path.substring(1).replace("/", "\\"));
			chain.doFilter(request, staticResp);
		}
		response.sendRedirect(request.getContextPath()+"/html/"+key);
		return ;
	}

	public void init(FilterConfig config) throws ServletException {
		this.config=config;
	}

}

StaticResponse.java

package com.filter;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;

import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

public class StaticResponse extends HttpServletResponseWrapper {

	HttpServletResponse resp;
	PrintWriter pw;
	public StaticResponse(HttpServletResponse response,String staticPath) {
		super(response);
		resp=response;
		try {
			pw=new PrintWriter(staticPath,"utf-8");
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	@Override
	public PrintWriter getWriter() throws IOException {
		return pw;
	}

}

DataDao.java

package com.servlet;

import java.io.IOException;
import java.io.PrintWriter;

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

import com.domain.Dao;

public class DataDao extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String category = request.getParameter("category");
		if(category==null||category.trim().isEmpty())
		{
			request.setAttribute("result", Dao.getAll());
		}
		else
		{
			request.setAttribute("result", Dao.getjava());
		}
		request.getRequestDispatcher("/show.jsp").forward(request, response);
		
	}

}

show.jsp

<%@ page language="java" import="java.util.*,com.domain.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core"  prefix="c"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'show.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>

   <c:forEach var="item" items="${result}">
   		<span style="color:${item.category==1?'red':'blue'}">${item.name}</span>
   </c:forEach>

  </body>
</html>

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
  
  <a href="${pageContext.request.contextPath}/servlet/DataDao">查看全部</a> 
  <a href="${pageContext.request.contextPath}/servlet/DataDao?category=1">看java</a> 
   
  </body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	
	<filter>
		<filter-name>StaticFilter</filter-name>
		<filter-class>com.filter.StaticFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>StaticFilter</filter-name>
		<url-pattern>/servlet/DataDao</url-pattern>
	</filter-mapping>	
	
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>DataDao</servlet-name>
    <servlet-class>com.servlet.DataDao</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>DataDao</servlet-name>
    <url-pattern>/servlet/DataDao</url-pattern>
  </servlet-mapping>

	
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>