android 下载工具

public interface DownloadFile {
public void download(String url, String destinationPath);

public interface Listener{
public void onSuccess(String url, String destinationPath);
public void onFailure(Exception e);
public void onProgressUpdate(int progress, int total);
}
}

public class DownloadFileUrlConnectionImpl implements DownloadFile {
private static final int KILOBYTE = 1024;

private static final int BUFFER_LEN = 1 * KILOBYTE;
private static final int NOTIFY_PERIOD = 150 * KILOBYTE;

Context context;
Handler uiThread;
Listener listener = new NullListener();

public DownloadFileUrlConnectionImpl(Context context, Handler uiThread, Listener listener) {
this.context = context;
this.uiThread = uiThread;
this.listener = listener;
}

@Override
public void download(final String url, final String destinationPath) {
new Thread(new Runnable() {
@Override
public void run() {
try{
File file = new File(destinationPath);
FileOutputStream fileOutput = new FileOutputStream(file);
HttpURLConnection urlConnection = null;
URL urlObj = new URL(url);
urlConnection = (HttpURLConnection) urlObj.openConnection();
int totalSize = urlConnection.getContentLength();
int downloadedSize = 0;
int counter = 0;
byte[] buffer = new byte[BUFFER_LEN];
int bufferLength = 0;
InputStream in = new BufferedInputStream(urlConnection.getInputStream());

while ( (bufferLength = in.read(buffer)) > 0 ) {
fileOutput.write(buffer, 0, bufferLength);
downloadedSize += bufferLength;
counter += bufferLength;
if(listener != null && counter > NOTIFY_PERIOD){
notifyProgressOnUiThread(downloadedSize, totalSize);
counter = 0;
}
}

urlConnection.disconnect();
fileOutput.close();

}catch(MalformedURLException e){
notifyFailureOnUiThread(e);
}catch(IOException e){
notifyFailureOnUiThread(e);
}

notifySuccessOnUiThread(url, destinationPath);
}
}).start();
}

protected void notifySuccessOnUiThread(final String url, final String destinationPath) {
if(uiThread == null)
return;

uiThread.post(new Runnable() {
@Override
public void run() {
listener.onSuccess(url, destinationPath);
}
});
}

protected void notifyFailureOnUiThread(final Exception e){
if(uiThread == null)
return;

uiThread.post(new Runnable() {
@Override
public void run() {
listener.onFailure(e);
}
});
}

private void notifyProgressOnUiThread(final int downloadedSize, final int totalSize) {
if(uiThread == null)
return;

uiThread.post(new Runnable() {
@Override
public void run() {
listener.onProgressUpdate(downloadedSize, totalSize);
}
});
}

protected class NullListener implements Listener{
public void onSuccess(String url, String destinationPath) {}
public void onFailure(Exception e) {}
public void onProgressUpdate(int progress, int total) {}
}
}