Java下載網絡文件常規寫法

	/**
	 * 從網絡Url中下載文件
	 * 
	 * @param urlStr
	 * @param fileName
	 * @param savePath
	 * @throws IOException
	 */
	public static String downLoadFromUrl(String urlStr, String fileName, String savePath) {
		try {
 
			URL url = new URL(urlStr);
			HttpURLConnection conn = (HttpURLConnection) url.openConnection();
			// 設置超時間爲3秒
			conn.setConnectTimeout(3 * 1000);
			// 防止屏蔽程序抓取而返回403錯誤
			conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
 
			// 得到輸入流
			InputStream inputStream = conn.getInputStream();
			// 獲取自己數組
			byte[] getData = readInputStream(inputStream);
 
			// 文件保存位置
			File saveDir = new File(savePath);
			if (!saveDir.exists()) {
				saveDir.mkdir();
			}
			File file = new File(saveDir + File.separator + fileName);
			FileOutputStream fos = new FileOutputStream(file);
			fos.write(getData);
			if (fos != null) {
				fos.close();
			}
			if (inputStream != null) {
				inputStream.close();
			}
			// System.out.println("info:"+url+" download success");
			return saveDir + File.separator + fileName;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "";
 
	}
 
	/**
	 * 從輸入流中獲取字節數組
	 * 
	 * @param inputStream
	 * @return
	 * @throws IOException
	 */
	public static byte[] readInputStream(InputStream inputStream) throws IOException {
		byte[] buffer = new byte[1024];
		int len = 0;
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		while ((len = inputStream.read(buffer)) != -1) {
			bos.write(buffer, 0, len);
		}
		bos.close();
		return bos.toByteArray();
	}