DownloadManager.class
在完成了編寫網(wǎng)絡(luò)請求高氮、下載進(jìn)度慧妄、線程等關(guān)鍵“零件”過后，我們現(xiàn)在要做的就是把這些零件通過一個核心骨架串聯(lián)剪芍，方便調(diào)用塞淹。這有點類似Java的代理模式一樣，需要一個或多個Class帶負(fù)責(zé)這些組件的邏輯運行∽锕現(xiàn)在饱普，我們要編寫一個完成這些職責(zé)的Class，這里就命名為DownloadManager.java：
/**
* Created by mid1529 on 2016/12/19.
* 下載管理方法
*/
public final class DownloadManager {
private static final String TAG = "DownloadManager";
public static final int HANDLER_DOWNLOAD_COMPLETED = 0x234123;
public static final int HANDLER_DOWNLOAD_FAILED = 0x12345234;
public static final int HANDLER_DOWNLOAD_PROGRESS = 0x2052344;
public static final int HANDLER_DOWNLOAD_CALL = 0x4234134;
@SuppressLint("StaticFieldLeak")
private static DownloadManager ourInstance = new DownloadManager();
private SQLiteDao mSQLiteDao = null;
private ArrayMap<Long, DownloadTask> mDownloadTaskQueue = null; //當(dāng)前下載任務(wù)的集合
private ArrayMap<Long, Call> mDownloadTaskCallQueue = null;
private DownloadService.DownloadServiceBinder mDownloadServiceBinder = null;
private ServiceConnection mServiceConnection = null;
private Application mApplication = null;
private DownloadCallback mDownloadCallback = null;
private DownloadHandler mHandler = null;
private boolean mIsDeleteHistory = false;
private ExecutorService mCachedThreadPool = null;
public synchronized static DownloadManager getInstance() {
if (ourInstance == null) {
synchronized (DownloadManager.class) {
ourInstance = new DownloadManager();
}
}
return ourInstance;
}
private DownloadManager() {
mDownloadTaskQueue = new ArrayMap<>();
mDownloadTaskCallQueue = new ArrayMap<>();
}
/**
* 在Application中調(diào)用此方法初始化
* 只有調(diào)用這方法后才可以正常運行坊谁，否則會報錯
*
* @param app Application
* @return DownloadManager實例
*/
public synchronized DownloadManager startService(Application app) {
if (mServiceConnection != null && mApplication != null)
return ourInstance;
mHandler = new DownloadHandler();
mCachedThreadPool = Executors.newCachedThreadPool();
mApplication = app;
Intent intent = new Intent(app, DownloadService.class);
mServiceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
try {
mDownloadServiceBinder = (DownloadService.DownloadServiceBinder) iBinder;
mDownloadServiceBinder.setHandler(mHandler);
} catch (Exception e) {
e.printStackTrace();
onDestory();
}
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
onDestory();
}
};
app.startService(intent);
app.bindService(intent, mServiceConnection, Context.BIND_AUTO_CREATE);
mSQLiteDao = new SQLiteDao(app);
return ourInstance;
}
/**
* 添加到下載隊列,阻塞線程费彼，建議到子線程操作
* 如果任務(wù)已存在隊列或者任務(wù)的url、filename不合法，也會添加錯誤
*
* @param task 下載任務(wù)
* @return 是否添加成功
*/
public boolean addTaskToQueue(DownloadTask task) {
if (!isDownloadTaskLegal(task)) //檢測下載任務(wù)的參數(shù)是否合法
return false;
checkInited();
DownloadTask query = mSQLiteDao.queryTask(task);
task.setPause(false);
if (query == null) {//不存在表中梯啤，執(zhí)行插入操作该抒，加入下載列表
mSQLiteDao.insertDownloadTask(task);
query = mSQLiteDao.queryTask(task);
task.setTaskId(query.getTaskId());
mDownloadTaskQueue.put(query.getTaskId(), query);
mDownloadServiceBinder.startDownload(task);
} else {
task.setTaskId(query.getTaskId());
if (mDownloadTaskQueue.get(task.getTaskId()) == null) {
task.setPause(false);
mDownloadTaskQueue.put(task.getTaskId(), task);
mDownloadServiceBinder.startDownload(task);
}
}
return true;
}
/**
* 驗證下載任務(wù)是否合法
*
* @param downloadTask 下載任務(wù)
* @return 是否合法
*/
@SuppressWarnings("RedundantIfStatement")
private boolean isDownloadTaskLegal(DownloadTask downloadTask) {
if (TextUtils.isEmpty(downloadTask.getFileName()))
return false;
if (TextUtils.isEmpty(downloadTask.getUrl()))
return false;
if (HttpUrl.parse(downloadTask.getUrl()) == null)
return false;
return true;
}
/**
* 暫停下載，并將下載任務(wù)從容器中移除
*
* @param task 下載的任務(wù)
*/
public void pauseDownload(DownloadTask task) {
task.setPause(true);
removeTaskFromQueue(task, false);
}
/**
* 從下載列表中移除下載任務(wù)
*
* @param downloadTask 下載任務(wù)
* @param isDeleteDbHistory 是否刪除對應(yīng)任務(wù)在數(shù)據(jù)庫中的記錄
*/
private void removeTaskFromQueue(final DownloadTask downloadTask, boolean isDeleteDbHistory) {
if (downloadTask.getTaskId() == null)
return;
DownloadTask task = mDownloadTaskQueue.get(downloadTask.getTaskId());
if (task != null) {
mDownloadTaskQueue.remove(task.getTaskId());
}
Call call = mDownloadTaskCallQueue.get(downloadTask.getTaskId());
if (call != null) {
call.cancel();
}
if (isDeleteDbHistory) { //不需要刪除
//noinspection ConstantConditions
mCachedThreadPool.execute(new Runnable() {
@Override
public void run() {
mSQLiteDao.deleteDownloadTaskByKey(downloadTask.getTaskId());
}
});
}
}
private void addCallToQueue(Long taskId, Call call) {
mDownloadTaskCallQueue.put(taskId, call);
}
/**
* 停止下載服務(wù)跪者，將會停止所有，且清空下載隊列，但不會刪除數(shù)據(jù)庫中下載記錄
*/
public void stopService() {
checkInited();
mDownloadTaskQueue.clear();
removeDownloadCallback();
if (mApplication == null)
return;
mApplication.stopService(new Intent(mApplication, DownloadService.class));
mApplication.unbindService(mServiceConnection);
}
/**
* 銷毀
* 清空Handler中的消息
* 清空用到的容器
* 將對象置為null
* 盡量減少內(nèi)存泄漏的可能
*/
private void onDestory() {
mHandler.removeCallbacksAndMessages(null);
mSQLiteDao = null;
mDownloadTaskQueue.clear(); //當(dāng)前下載任務(wù)的集合
mDownloadTaskCallQueue.clear();
mDownloadServiceBinder = null;
mServiceConnection = null;
mCachedThreadPool.shutdown();
mCachedThreadPool = null;
mApplication = null;
}
/**
* 檢查是否已經(jīng)調(diào)用start()方法初始化小染，沒有則直接拋異常
*/
private void checkInited() {
if (mDownloadServiceBinder == null) {
throw new NullPointerException("Do you remember invok \"DownloadManager.getInstance().start()\" in your Application.class? ");
}
}
/**
* @return 返回Dao
*/
public List<DownloadTask> getDownloadTask() {
checkInited();
return mSQLiteDao.queryAllTask();
}
/**
* 設(shè)置下載回調(diào)監(jiān)聽
*
* @param callback 回調(diào)
*/
public void setDownloadCallback(DownloadCallback callback) {
this.mDownloadCallback = callback;
}
/**
* 移除監(jiān)聽
*/
public void removeDownloadCallback() {
this.mDownloadCallback = null;
}
/**
* 更新下載任務(wù)到數(shù)據(jù)庫
*
* @param downloadTask 下載任務(wù)
*/
private void updateDownloadTask(final DownloadTask downloadTask) {
mCachedThreadPool.execute(new Runnable() {
@Override
public void run() {
mSQLiteDao.updateDownloadTask(downloadTask);
}
});
}
/**
* 清空下載的信息
*
* @param downloadTask 下載任務(wù)
*/
private void cleanDownloadInfo(final DownloadTask downloadTask) {
mCachedThreadPool.execute(new Runnable() {
@Override
public void run() {
removeTaskFromQueue(downloadTask, mIsDeleteHistory);
}
});
}
/**
* 是否在下載失敗或完成后，刪除下載任務(wù)
*
* @return 是否刪除
*/
public boolean isDeleteHistory() {
return mIsDeleteHistory;
}
/**
* 設(shè)置是否刪除下載任務(wù)的記錄
*
* @param deleteHistory 是否刪除
*/
public void setDeleteHistory(boolean deleteHistory) {
mIsDeleteHistory = deleteHistory;
}
/**
* Handler負(fù)責(zé)處理進(jìn)度傳遞消息等
*/
@SuppressWarnings("unchecked")
private static class DownloadHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case HANDLER_DOWNLOAD_PROGRESS:
getInstance().updateDownloadTask((DownloadTask) msg.obj);
getInstance().mDownloadCallback.onProgress((DownloadTask) msg.obj);
break;
case HANDLER_DOWNLOAD_COMPLETED:
getInstance().cleanDownloadInfo((DownloadTask) msg.obj);
getInstance().mDownloadCallback.onComplete((DownloadTask) msg.obj);
break;
case HANDLER_DOWNLOAD_FAILED:
getInstance().cleanDownloadInfo((DownloadTask) msg.obj);
getInstance().mDownloadCallback.onDownloadFaild((DownloadTask) msg.obj);
break;
case HANDLER_DOWNLOAD_CALL:
if (msg.obj instanceof ArrayMap) {
ArrayMap<Long, Call> map = (ArrayMap<Long, Call>) msg.obj;
if (map.size() != 0) {
getInstance().addCallToQueue(map.keyAt(0), map.get(map.keyAt(0)));
}
}
break;
}
}
}
}
典型的贮折，因為一個App中只需要一個下載管理實例裤翩，所以我們控制只能用單例模式獲取DownloadManager實例，然后進(jìn)行通信调榄。有興趣的參考注釋閱讀踊赠。
總結(jié)
這個項目中，在提取網(wǎng)絡(luò)Header中的數(shù)據(jù)時每庆，采用正則表達(dá)式提取筐带，比如Range，這種做法總感覺不科學(xué)缤灵，但不知道有什么方法獲取到伦籍，這里就謙虛謙虛，誰能告知下科學(xué)方法腮出。
整體思路就是這樣帖鸦，現(xiàn)在只是V0.2版本，很多地方不是很嚴(yán)謹(jǐn)胚嘲，很多地方偷懶作儿，過兩天再改善吧。
流程圖及整體Project周日會放到GitHub中慢逾，有興趣的可以看看
到這里算是結(jié)束了這為期三天的水文立倍，能靜下來寫點東西還真不容易灭红，好好堅持吧。
Lolipop
