一、目标
本章實作視訊下載下傳的功能
使用說明：進入線上視訊，點選播放時将彈出選擇框詢問播放還是下載下傳，點選下載下傳後進度條将在本地視訊頂部顯示。如果想邊看便下載下傳，請直接點選本地播放清單中正在下載下傳的視訊。 二、實作（部分主要實作代碼）
FileDownloadHelper
public class FileDownloadHelper {
private static final String TAG = "FileDownloadHelper";
/** 線程池 */
private ThreadPool mPool = new ThreadPool();
/** 開始下載下傳 */
public static final int MESSAGE_START = 0;
/** 更新進度 */
public static final int MESSAGE_PROGRESS = 1;
/** 下載下傳結束 */
public static final int MESSAGE_STOP = 2;
/** 下載下傳出錯 */
public static final int MESSAGE_ERROR = 3;
/** 中途終止 */
private volatile boolean mIsStop = false;
private Handler mHandler;
public volatile HashMap<String, String> mDownloadUrls = new HashMap<String, String>();
public FileDownloadHelper(Handler handler) {
if (handler == null)
throw new IllegalArgumentException("handler不能為空!");
this.mHandler = handler;
}
public void stopALl() {
mIsStop = true;
mPool.stop();
public void newDownloadFile(final String url) {
newDownloadFile(url, Environment.getExternalStorageDirectory() + "/" + FileUtils.getUrlFileName(url));
/**
* 下載下傳一個新的檔案
*
* @param url
* @param savePath
*/
public void newDownloadFile(final String url, final String savePath) {
if (mDownloadUrls.containsKey(url))
return;
else
mDownloadUrls.put(url, savePath);
mPool.start(new Runnable() {
@Override
public void run() {
mHandler.sendMessage(mHandler.obtainMessage(MESSAGE_START, url));
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(url);
InputStream inputStream = null;
FileOutputStream outputStream = null;
try {
HttpResponse response = client.execute(get);
HttpEntity entity = response.getEntity();
final int size = (int) entity.getContentLength();
inputStream = entity.getContent();
if (size > 0 && inputStream != null) {
outputStream = new FileOutputStream(savePath);
int ch = -1;
byte[] buf = new byte[1024];
//每秒更新一次進度
new Timer().schedule(new TimerTask() {
@Override
public void run() {
try {
FileInputStream fis = new FileInputStream(new File(savePath));
int downloadedSize = fis.available();
if (downloadedSize >= size)
cancel();
mHandler.sendMessage(mHandler.obtainMessage(MESSAGE_PROGRESS, downloadedSize, size, url));
} catch (Exception e) {
}
}
}, 50, 1000);
while ((ch = inputStream.read(buf)) != -1 && !mIsStop) {
outputStream.write(buf, 0, ch);
}
outputStream.flush();
}
} catch (Exception e) {
Log.e(TAG, e.getMessage(), e);
mHandler.sendMessage(mHandler.obtainMessage(MESSAGE_ERROR, url + ":" + e.getMessage()));
} finally {
try {
if (outputStream != null)
outputStream.close();
} catch (IOException ex) {
if (inputStream != null)
inputStream.close();
}
mDownloadUrls.remove(url);
mHandler.sendMessage(mHandler.obtainMessage(MESSAGE_STOP, url));
}
});
代碼說明：
a. ThreadPool是線程池，請參照項目代碼。
b. 這裡使用了Time定時來刷進度，而沒有直接在write資料時更新進度，這樣的原因時每秒write較高，更新UI過于頻繁，可能導緻逾時等問題。
Handle
public Handler mDownloadHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
PFile p;
String url = msg.obj.toString();
switch (msg.what) {
case FileDownloadHelper.MESSAGE_START://開始下載下傳
p = new PFile();
p.path = mParent.mFileDownload.mDownloadUrls.get(url);
p.title = new File(p.path).getName();
p.status = 0;
p.file_size = 0;
if (mDownloadAdapter == null) {
mDownloadAdapter = new FileAdapter(getActivity(), new ArrayList<PFile>());
mDownloadAdapter.add(p, url);
mTempListView.setAdapter(mDownloadAdapter);
mTempListView.setVisibility(View.VISIBLE);
} else {
mDownloadAdapter.notifyDataSetChanged();
break;
case FileDownloadHelper.MESSAGE_PROGRESS://正在下載下傳
p = mDownloadAdapter.getItem(url);
p.temp_file_size = msg.arg1;
p.file_size = msg.arg2;
int status = (int) ((msg.arg1 * 1.0 / msg.arg2) * 10);
if (status > 10)
status = 10;
p.status = status;
mDownloadAdapter.notifyDataSetChanged();
case FileDownloadHelper.MESSAGE_STOP://下載下傳結束
FileBusiness.insertFile(getActivity(), p);
case FileDownloadHelper.MESSAGE_ERROR:
Toast.makeText(getActivity(), url, Toast.LENGTH_LONG).show();
super.handleMessage(msg);
}
a. mTempListView是新增的，預設是隐藏，請參見項目代碼layout部分。
b. 下載下傳流程：開始(顯示mTempListView) -> 正在下載下傳(更新進度圖檔和大小) -> 完成（入褲）
Dialog
if (FileUtils.isVideoOrAudio(url)) {
Dialog dialog = new AlertDialog.Builder(getActivity()).setIcon(android.R.drawable.btn_star).setTitle("播放/下載下傳").setMessage(url).setPositiveButton("播放", new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(getActivity(), VideoPlayerActivity.class);
intent.putExtra("path", url);
startActivity(intent);
}).setNeutralButton("下載下傳", new OnClickListener() {
MainFragmentActivity activity = (MainFragmentActivity) getActivity();
activity.mFileDownload.newDownloadFile(url);
Toast.makeText(getActivity(), "正在下載下傳 .." + FileUtils.getUrlFileName(url) + " ，可從本地視訊檢視進度！", Toast.LENGTH_LONG).show();
}).setNegativeButton("取消", null).create();
dialog.show();
return true;
三、下載下傳
至本章節往後，代碼均不再提供下載下傳，請移步Google Code：
![Java小案例——随機數猜測随機數猜測[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)