Android: 通过URL下载文件

URL url = new URL(urlString);
File tempFile = null;
tempFile = File.createTempFile("cache", ".tmp", new File(Environment.getExternalStorageDirectory().toString()));
boolean downloaded = DownloadUtils.requestDownload(url, tempFile);

public class DownloadUtils {
    private static final String TAG = "DownloadService";

    public static boolean requestDownload(URL url, File file) {
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(file);
            return download(url, fos);
        } catch (Throwable t) {
            return false;
        } finally {
            Utils.closeSilently(fos);
        }
    }

    public static void dump(InputStream is, OutputStream os)
            throws IOException {
        byte buffer[] = new byte[4096];
        int rc = is.read(buffer, 0, buffer.length);
        final Thread thread = Thread.currentThread();

        while (rc > 0) {
            os.write(buffer, 0, rc);
            rc = is.read(buffer, 0, buffer.length);
        }

        Thread.interrupted(); // consume the interrupt signal
    }

    public static boolean download(URL url, OutputStream output) {
        InputStream input = null;
        try {
            input = url.openStream();
            dump(input, output);
            return true;
        } catch (Throwable t) {
            Log.w(TAG, "fail to download", t);
            return false;
        } finally {
            Utils.closeSilently(input);
        }
    }
}