关于编码的问题有几点需要说清楚:UTF-8 国际编码,GBK 中文编码。GBK 包含 GB2312,即如果通过 GB2312 编码后可以通过 GBK 解码,反之可能不成立;英文文字就是 26 个字母,真正的对应关系就是 ASCII 码表中的关系,但是如何表示汉字呢?很显然也需要一套对应的码表,于是 UTF-8、GBK、GB2312 这些编码方式就是为了解决这个问题的。
下面看看正题:首先我的目录是:压缩包即是我要下载的文件

我的下载界面:
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| <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> </head> <body> <h3> 使用 a 标签指向服务器资源 </h3> <a href="/Web14_response/download/a.flv">a.flv</a><br> <a href="/Web14_response/download/a.jpg">a.jpg</a><br> <a href="/Web14_response/download/a.mp3">a.mp3</a><br> <a href="/Web14_response/download/a.mp4">a.mp4</a><br> <a href="/Web14_response/download/a.txt">a.txt</a><br> <a href="/Web14_response/download/a.zip">a.zip</a><br> <h3> 使用服务器代码完成服务器资源下载 </h3> <a href="/Web14_response/DownloadServlet2?filename=a.flv">a.flv</a><br> <a href="/Web14_response/DownloadServlet2?filename=a.jpg">a.jpg</a><br> <a href="/Web14_response/DownloadServlet2?filename=a.mp3">a.mp3</a><br> <a href="/Web14_response/DownloadServlet2?filename=a.mp4">a.mp4</a><br> <a href="/Web14_response/DownloadServlet2?filename=a.txt">a.txt</a><br> <a href="/Web14_response/DownloadServlet2?filename = 压缩包.zip"> 压缩包.zip</a><br> </body> </html>
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提供文件下载的 Servlet:
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| package com.xpu.content; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.net.URLEncoder; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import sun.misc.BASE64Encoder; public class DownloadServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String filename = request.getParameter ("filename"); filename = new String(filename.getBytes ("ISO8859-1"), "UTF-8"); response.setContentType (getServletContext ().getMimeType (filename)); String agent = request.getHeader ("User-Agent"); String filenameEncoder = ""; if (agent.contains ("MSIE")) { filenameEncoder = URLEncoder.encode (filename, "utf-8"); filenameEncoder = filename.replace ("+", " "); } else if (agent.contains ("Firefox")) { BASE64Encoder base64Encoder = new BASE64Encoder(); filenameEncoder = "=?utf-8?B?" + base64Encoder.encode (filename.getBytes ("utf-8")) + "?="; } else { filenameEncoder = URLEncoder.encode (filename, "utf-8"); } response.setHeader ("Content-Disposition", "attachment;filename=" + filenameEncoder); System.out.println (filename); String path = getServletContext ().getRealPath ("/download/" + filename); InputStream is = new FileInputStream(path); ServletOutputStream os = response.getOutputStream (); int len = 0; byte[] bys = new byte[1024]; while ((len = is.read (bys)) != -1) { os.write (bys, 0, len); } is.close (); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet (request, response); } }
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下载效果:
