JAVA实现网络文件下载

		HttpURLConnection conn = null;

		OutputStream outputStream = null;

		InputStream inputStream = null;

		try {

			String path = r.getParameter("filename");

			File fl = new File(path);

			URL url = new URL(path);

			conn = (HttpURLConnection)url.openConnection();

			inputStream = conn.getInputStream();

			rp.reset();

			rp.setHeader("Content-Disposition", "attachment;filename=\""+ fl.getName() + "\"");

			rp.setContentType("application/octet-stream");

			rp.setContentLength((int)conn.getContentLength());

			rp.setHeader("Pragma", "No-cache");

			rp.setHeader("Cache-Control", "No-cache");

			rp.setDateHeader("Expires", 0);

			outputStream = new BufferedOutputStream(rp.getOutputStream());

			byte[] buffer = new byte[4096];

			int len = 0;

			while((len = inputStream.read(buffer)) != -1) {

				outputStream.write(buffer, 0, len);

			}

			outputStream.flush();

		} catch(Exception e){

			e.printStackTrace();

		} finally {

			if(conn!=null){

				conn.disconnect();

			}

			if(inputStream != null) {

				inputStream.close();

			}

			if(outputStream != null) {

				outputStream.close();

			}

		}