JAVA Servlet文件下载的几种方式

  public  HttpServletResponse download(String path, HttpServletResponse response) {         try  {             //  path是指欲下载的文件的路径。             File file  =   new  File(path);             //  取得文件名。             String filename  =  file.getName();             //  取得文件的后缀名。             String ext  =  filename.substring(filename.lastIndexOf( " . " )  +   1 ).toUpperCase();             //  以流的形式下载文件。             InputStream fis  =   new  BufferedInputStream( new  FileInputStream(path));             byte [] buffer  =   new   byte [fis.available()];            fis.read(buffer);            fis.close();             //  清空response             response.reset();             //  设置response的Header             response.addHeader( " Content-Disposition " ,  " attachment;filename= "   +   new  String(filename.getBytes()));            response.addHeader( " Content-Length " ,  ""   +  file.length());            OutputStream toClient  =   new  BufferedOutputStream(response.getOutputStream());            response.setContentType( " application/octet-stream " );            toClient.write(buffer);            toClient.flush();            toClient.close();        }  catch  (IOException ex) {            ex.printStackTrace();        }         return  response;    }     public   void  downloadLocal(HttpServletResponse response)  throws  FileNotFoundException {         //  下载本地文件         String fileName  =   " Operator.doc " .toString();  //  文件的默认保存名         //  读到流中         InputStream inStream  =   new  FileInputStream( " c:/Operator.doc " ); //  文件的存放路径         //  设置输出的格式         response.reset();        response.setContentType( " bin " );        response.addHeader( " Content-Disposition " ,  " attachment; filename=\ ""  + fileName +  " \ "" );         //  循环取出流中的数 据          byte [] b  =   new   byte [ 100 ];         int  len;         try  {             while  ((len  =  inStream.read(b))  >   0 )                response.getOutputStream().write(b,  0 , len);            inStream.close();        }  catch  (IOException e) {            e.printStackTrace();        }    }     public   void  downloadNet(HttpServletResponse response)  throws  MalformedURLException {         //  下载网络文件          int  bytesum  =   0 ;         int  byteread  =   0 ;        URL url  =   new  URL( " windine.blogdriver.com/logo.gif " );         try  {            URLConnection conn  =  url.openConnection();            InputStream inStream  =  conn.getInputStream();            FileOutputStream fs  =   new  FileOutputStream( " c:/abc.gif " );             byte [] buffer  =   new   byte [ 1204 ];             int  length;             while  ((byteread  =  inStream.read(buffer))  !=   - 1 ) {                bytesum  +=  byteread;                System.out.println(bytesum);                fs.write(buffer,  0 , byteread);            }        }  catch  (FileNotFoundException e) {            e.printStackTrace();        }  catch  (IOException e) {            e.printStackTrace();        }    }//支持在线打开文件的一种方式     public   void  downLoad(String filePath, HttpServletResponse response,  boolean  isOnLine)  throws  Exception {        File f  =   new  File(filePath);         if  ( ! f.exists()) {            response.sendError( 404 ,  " File not found! " );             return ;        }        BufferedInputStream br  =   new  BufferedInputStream( new  FileInputStream(f));         byte [] buf  =   new   byte [ 1024 ];         int  len  =   0 ;        response.reset();  //  非常重要          if  (isOnLine) {  //  在线打开方式             URL u  =   new  URL( " file:/// "   +  filePath);            response.setContentType(u.openConnection().getContentType());            response.setHeader( " Content-Disposition " ,  " inline; filename= "   +  f.getName());             //  文件名应该编码成UTF-8         }  else  {  //  纯下载方式             response.setContentType( " application/x-msdownload " );            response.setHeader( " Content-Disposition " ,  " attachment; filename= "   +  f.getName());        }        OutputStream out  =  response.getOutputStream();         while  ((len  =  br.read(buf))  >   0 )            out.write(buf,  0 , len);        br.close();        out.close();    }