文件下载

public   class  DownloadServlet  extends  HttpServlet {
     private  String contentType  =   " application/x-msdownload " ;
     private  String enc  =   " utf-8 " ;
     private  String fileRoot  =   "" ;


     /**
     * 初始化contentType，enc，fileRoot
      */
     public   void  init(ServletConfig config)  throws  ServletException {
        String tempStr  =  config.getInitParameter( " contentType " );
         if  (tempStr  !=   null   &&   ! tempStr.equals( "" )) {
            contentType  =  tempStr;
        }
        tempStr  =  config.getInitParameter( " enc " );
         if  (tempStr  !=   null   &&   ! tempStr.equals( "" )) {
            enc  =  tempStr;
        }
        tempStr  =  config.getInitParameter( " fileRoot " );
         if  (tempStr  !=   null   &&   ! tempStr.equals( "" )) {
            fileRoot  =  tempStr;
        }
    }

     protected   void  doGet(HttpServletRequest request, HttpServletResponse response)  throws  ServletException, IOException {
        String filepath  =  request.getParameter( " filepath " );
        String fullFilePath  =  fileRoot  +  filepath;
         /* 读取文件 */
        File file  =   new  File(fullFilePath);
         /* 如果文件存在 */
         if  (file.exists()) {
            String filename  =  URLEncoder.encode(file.getName(), enc);
            response.reset();
            response.setContentType(contentType);
            response.addHeader( " Content-Disposition " ,  " attachment; filename=\ ""  + filename +  " \ "" );
             int  fileLength  =  ( int ) file.length();
            response.setContentLength(fileLength);
             /* 如果文件长度大于0 */
             if  (fileLength  !=   0 ) {
                 /* 创建输入流 */
                InputStream inStream  =   new  FileInputStream(file);
                 byte [] buf  =   new   byte [ 4096 ];
                 /* 创建输出流 */
                ServletOutputStream servletOS  =  response.getOutputStream();
                 int  readLength;
                 while  (((readLength  =  inStream.read(buf))  !=   - 1 )) {
                    servletOS.write(buf,  0 , readLength);
                }
                inStream.close();
                servletOS.flush();
                servletOS.close();
            }
        }
    }

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public class Download extends HttpServlet {

 public void init(ServletConfig config) throws ServletException {
  super.init(config);
  //TODO Method stub generated by Lomboz
 }

 public void destroy() {
  super.destroy();
  //TODO Method stub generated by Lomboz
 }

 protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  
  String root = getServletContext().getRealPath("/");
     String path = request.getParameter("path");
     String name = request.getParameter("name");

     response.setContentType("text/x-msdownload");
     response.addHeader("Content-Disposition","attachment; filename=\"" + name + "\"");
    
     try
     {
         java.io.OutputStream    os  = response.getOutputStream();
         java.io.FileInputStream fis = new java.io.FileInputStream(root + path + name);
        
         byte[] b = new byte[1024];
         int    i = 0;
        
         while ( (i = fis.read(b)) > 0 )
         {
             os.write(b, 0, i);
         }
        
         fis.close();
         os.flush();
         os.close();
     }
     catch ( Exception e )
     {
      e.printStackTrace();
     }
  
 }
}

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