Http方式下载Servlet实现

Http方式下载，Servlet实现

与普通的Servlet处理请求类似，浏览器端输入URL，该URL由tomcat分配给相应的Servlet进行处理，以下为示例代码：

 1 public void service(HttpServletRequest req, HttpServletResponse res) {
 2     
 3     File file = new File(fileName);
 4     if(file.exists()) {
 5         FileInputStream in = new FileInputStream(file);
 6         try {
 7             res.setContentType("application/zip");
 8             res.setContentLength( (int)file.length() );
 9             res.setHeader("Content-Disposition", "attachment; filename=\""+fileName+"\"");
10             ServletOutputStream out = res.getOutputStream();
11             int read = 0;
12             byte buf[] = new byte[4096];
13             while ((read = in.read(buf, 0, 4096)) != -1)
14             {
15                 out.write(buf, 0, read);
16             }
17             if (out != null)
18             {
19                 out.close();
20             }
21             in.close();
22             file.delete();
23         } catch (IOException e) {
24             System.out.println(fileName+" 文件下载出错");
25             e.printStackTrace();
26         }
27     } else {
28         System.out.println(fileName+" 文件不存在");
29     }
30 }