下载文件

通过URL，下载文件，并且保存在SD卡上

首先通过URL获得数据流

public InputStream getInputStreamFromUrl(String strUrl) {

	InputStream input = null;

	try {
		URL url = new URL(strUrl);
		HttpURLConnection urlCon = (HttpURLConnection) url.openConnection();
		input = urlCon.getInputStream();
	} catch (IOException e) {
		e.printStackTrace();
	}

	return input;
}

将数据流保存成文件

public File saveFileFromInput(String fileName, InputStream input) {

	File file = null;
	OutputStream output = null;

	try {
		createDir(mSDPath);
		file = createFile(fileName);

		output = new FileOutputStream(file);
		byte buffer[] = new byte[4 * 1024];
		while (input.read(buffer) != -1) {
			output.write(buffer);
		}

		output.flush();

	} catch (Exception e) {
		e.printStackTrace();
	} finally {
		try {
			output.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	return file;
}

(重要)如果无法保存，请查看是否添加必要Permission

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />