快速掌握servlet技术-d1_2

最新推荐文章于 2025-07-31 11:19:14 发布

原创最新推荐文章于 2025-07-31 11:19:14 发布 · 333 阅读

0 ·

CC 4.0 BY-SA版权

Java 专栏收录该内容

8 篇文章

订阅专栏

本文详细解析了HTTP响应的各个组成部分，包括状态码的意义及其用途，如200 OK、302重定向、404未找到及500服务器错误等。此外还介绍了多种消息头字段的作用，例如Location用于重定向，Content-Type定义文档编码类型。

http响应：

HTTP/1.1 200 OK ---状态行

Server:Microsoft-IIS/6.0

Date:

Content-Length:

Content-Type: -----------------多个消息头

Cache-control: private

--------空行

…html代码

常用状态吗:

200 OK
302让浏览器转向另个资源(response.setStatus(302),response.setHeader(“Location”,”/servlet/test”)这个呢就是sendRedriect的底层实现);
404 找不到资源
500 服务器内部错误

消息头:

Location:http://www.xxx.com[让浏览器重新定位到rul]

Server:apache tomcat[告诉浏览器服务器使用的是tomcat]

Content-Encoding:gzip [使用gzip压缩]

Content-Length: 500 [告诉浏览器发送过去的字节数]

Content-Language:zh-cn [队中文的支持]

Content-Type: text/html;charset=gb3212[文档编码]

Last-Modified: [访问资源的更新时间]

Refresh: 2;url=。。。告诉浏览器过多久刷新到url]

Content-Disposition:attachment;filename=aaa.zip; [下载资源]

Transfer-Encoding:chunked [校验传输的编码]

Set-Cookie:SS=…

Expires:-1 [指定缓存,如何缓存数据IE]

Cache-Control:no-cache 火狐

Pragma:no-cache

Connection:close/Keep-Alive

Date:

实现页面跳转：

		response.setStatus(302);
		response.setHeader("Location", "/ServletStudy/Link");

页面各多久跳转：

response.setHeader("Refresh","3;url=/ServletStudy/Link");

防盗链：

		String checkAddress = "localhost:8080/ServletStudy";
		String referer = request.getHeader("Referer");
		//这里判断条件不能写反啦 如果反啦就会出现使用NULL去调用indexof 发生Exception
		if(referer != null && referer.indexOf(checkAddress) != -1){
			out.println("正确链接");
		}else{
			out.println(" 盗链");
		}

最后做一个下载的页面：

要求：可以下载文件，并防止盗链接，禁用页面缓存

请求代码:

package com.codeguy.d1.protocol;

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;

public class Link extends HttpServlet {

	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		response.setDateHeader("Expires", 0);
		response.setHeader("Cache-Control", "no-cache");
		response.setHeader("Pragma", "no-cache");
		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");
		out.println("<a href='/ServletStudy/DownLoad'>stardict-3.0.2.tar.bz2</a>");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);
	}

}

下载页面代码:

package com.codeguy.d1.protocol;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;

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

import org.w3c.dom.ls.LSException;

public class DownLoad extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=utf-8");

		OutputStream os = response.getOutputStream();
		String checkAddress = "localhost:8080/ServletStudy";
		String referer = request.getHeader("Referer");
		
		if(!(referer != null && referer.indexOf(checkAddress) != -1)){
		        os.write(" 盗链".getBytes());
			return;
		}
		
		String path = this.getServletContext().getRealPath("/file/stardict-3.0.2.tar.bz2");
		response.setHeader("Content-Disposition", "attachment;filename=stardict-3.0.2.tar.bz2");

		
		FileInputStream fis = new FileInputStream(path);
		int len = 0;
		byte[] buf = new byte[1024];
		while((len=fis.read(buf))>0){
			os.write(buf,0,len);
		}
		os.close();
		fis.close();
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);
	}

}