Android程序函数 将assets文件夹下的文件复制到手机的sd

最近Android吧在做个功能是将asset文件夹下的所有文件（包括子文件）全部拷贝出来到指定目录下。所用的方法无非是用AssetManager。但是这里有个问题是也要讲子文件夹和子文件都要拷贝出来。到网上Google了下，也到baidu搜索了下，发现了很多类似问题。但好像都有问题。有些显然只能做到将asset直接目录下的文件拷贝出来，但子文件夹拷贝不出来，而且，碰到文件夹，会抛异常。无奈自己只好动手写了个。如下：

private void CopyAssets(String assetDir, String dir) {
		String[] files;
		try {
			files = this.getResources().getAssets().list(assetDir);
		} catch (IOException e1) {
			return;
		}
		File mWorkingPath = new File(dir);
		// if this directory does not exists, make one.
		if (!mWorkingPath.exists()) {
			if (!mWorkingPath.mkdirs()) {

			}
		}
		for (int i = 0; i < files.length; i++) {
			try {
				String fileName = files[i];
				// we make sure file name not contains '.' to be a folder.
				if (!fileName.contains(".")) {
					if (0 == assetDir.length()) {
						CopyAssets(fileName, dir + fileName + "/");
					} else {
						CopyAssets(assetDir + "/" + fileName, dir + fileName
								+ "/");
					}
					continue;
				}
				File outFile = new File(mWorkingPath, fileName);
				if (outFile.exists())
					outFile.delete();
				InputStream in = null;
				if (0 != assetDir.length()) {
					in = getAssets().open(assetDir + "/" + fileName);
				} else {
					in = getAssets().open(fileName);
				}
				OutputStream out = new FileOutputStream(outFile);

				// Transfer bytes from in to out
				byte[] buf = new byte[1024];
				int len;
				while ((len = in.read(buf)) > 0) {
					out.write(buf, 0, len);
				}
			} catch (Exception e) {
				e.printStackTrace();
			}

		}
	}

非原创，原文出处： http://tieba.baidu.com/f?kz=1096393066