JavaWeb批量下载HTTP文件

/**
     * java下载文件
     * @throws FileNotFoundException
     */
    public void downloadFile() throws FileNotFoundException {
        File resource = new File("c:resource.txt");
        File target = new File("d:target.txt");
        //文件输入流，传入需要下载的文件对象
        FileInputStream inputStream = new FileInputStream(resource);
        //文件输出流，传入需要写入数据的文件对象
        FileOutputStream outputStream = new FileOutputStream(target);
        //用来装输入流读取的字节
        byte [] bytes = new byte[1024];
        //记录读取的字节长度
        int len;
        try {
            //inputStream将输入流中的字节放入bytes中，读完所有字节则返回-1
            while ((len = inputStream.read(bytes)) != -1){
                outputStream.write(bytes, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭输入输出流
            try {
                if(inputStream != null){
                    inputStream.close();
                }
                if (outputStream != null){
                    outputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

//全部字节一次读，一次写
byte[] bytes = new byte[inputStream.available()];
        inputStream.read(bytes);
        outputStream.write(bytes);

//每次读1024个字节，将读出的字节全部写入，直至所有内容读完写完
byte[] bytes = new byte[1024];
            while ((len = in.read(bytes)) != -1){
                out.write(bytes, 0, len);
            }

public void downloadFile(HttpServletResponse response, String path, String fileName){
        OutputStream out = null;
        URL url;
        InputStream in = null;
        int len = 0;
        try{
            //取得HTTP文件的URL对象
            url = new URL(path);
            //获取该URL对象的连接
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            //连接的相关属性设置
            connection.setConnectTimeout(3 * 1000);
            connection.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
            //获取该连接的字节输入流
            in = connection.getInputStream();
            //设置响应头相关属性
            response.setHeader("Content-Disposition", "attachment; filename=" + fileName);
            response.setContentType("application/force-download");
            //获取响应头的字节输出流，装饰为缓冲流提高读写效率
            out = new BufferedOutputStream(response.getOutputStream());
            byte[] bytes = new byte[1024];
            while ((len = in.read(bytes)) != -1){
                out.write(bytes, 0, len);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            try {
                if (in != null) {
                    in.close();
                }
                if (out != null){
                    out.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

public void downloadHttpFileByZip(HttpServletResponse response, List<String> paths, List<String> fileNames) throws IOException{
		//需要生成的压缩文件名
		String fileName = UUID.randomUUID().toString() + ".zip";
		String outFilePath = "d:" + fileName;
		//生成该压缩文件
		File file = new File(outFilePath);
		FileOutputStream outStream;
		try {
			//将压缩文件放入文件输出流
			outStream = new FileOutputStream(file);
			//使用压缩输出流装饰文件输出流
			ZipOutputStream zipStream = new ZipOutputStream(outStream);
			zipFile(paths, fileNames, zipStream);
			//一定要先关闭压缩输出流，再使用压缩文件，否则压缩文件会不正确
			zipStream.close();
			outStream.close();
			
			//同JavaWeb下载文件
			BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file.getPath()));
			OutputStream os = new BufferedOutputStream(response.getOutputStream());
			response.setHeader("Content-Disposition", "attachment; filename="+fileName);
		    response.setContentType("application/force-download");
		    byte[] bytes = new byte[1024];
			int len = 0;
			while((len = bis.read(bytes)) != -1){
				os.write(bytes, 0, len);
            }
			bis.close();
		    os.flush();
		    os.close();
		    //关闭流之后再删除文件，否则会删除失败
		    file.delete();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}
	
	//循环获取HTTP文件，并写入压缩输出流
	private void zipFile(List<String> paths, List<String> fileNames, ZipOutputStream os) throws IOException{
		URL url;
		InputStream inputStream = null;
		for(int i = 0 ; i < paths.size(); i++){
			url = new URL(paths.get(i));
			HttpURLConnection conn = (HttpURLConnection)url.openConnection();
		    conn.setConnectTimeout(3*1000);
		    inputStream = conn.getInputStream();
		    zipFile(inputStream, os, fileNames.get(i));
		}
	}
	
	//将输入流中的字节通过压缩输出流写入压缩文件中
	private void zipFile(InputStream is, ZipOutputStream os, String fileName) throws IOException{
		if(is != null){
			BufferedInputStream bis = new BufferedInputStream(is);
			//压缩包内的文件对象
			ZipEntry entry = new ZipEntry(fileName);
			//将该文件对象放入压缩输出流
			os.putNextEntry(entry);			
			byte[] bytes = new byte[1024];
			int len = 0;
			//将输入流中的字节写入输出流中的文件对象
			while((len = bis.read(bytes)) != -1){  
				os.write(bytes, 0, len);  
            }
            //写完就关闭流，保证文件的正确性
			os.closeEntry();
			bis.close();
			is.close();
		}
	}