Download Manager : Download « Network « Android

1. Android
2. Network
3. Download

Download Manager

  
/*   
 * Copyright 2010 John R. Hicks
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

//package com.determinato.feeddroid.util;

import java.util.Collection;
import java.util.concurrent.ConcurrentLinkedQueue;

import android.os.Handler;

public class DownloadManager {
  private static final String TAG = "DownloadManager";
  private static final int TIMEOUT = 8000;
  
  private Handler mHandler;
  
  private ConcurrentLinkedQueue<DownloadWrapper> mThreads =
    new ConcurrentLinkedQueue<DownloadWrapper>();
  
  private ConcurrentLinkedQueue<Runnable> mQueue =
    new ConcurrentLinkedQueue<Runnable>();
  
  public DownloadManager(Handler handler) {
    mHandler = handler;
  }
  
  public boolean schedule(Runnable r) {
    mQueue.add(r);
    
    if (mThreads.size() == 0) {
      mHandler.removeCallbacks(mWakeUp);
      mWakeUp.run();
      return true;
    }
    
    return false;
  }
  
  private Runnable mWakeUp = new Runnable() {
    public void run() {
      Runnable r = mQueue.poll();
      
      if (r == null) {
        // Woke up with noting to do.
        return;
      } 
      
      for (DownloadWrapper t: mThreads) {
        t.tooSlow();
      }
      
      DownloadWrapper t = new DownloadWrapper(mThreads, mHandler, r);
      mThreads.add(t);
      t.start();
      
      mHandler.removeCallbacks(this);
      mHandler.postDelayed(this, TIMEOUT);
      
      
    }
  };
  
  private class DownloadWrapper extends Thread {
    Collection<DownloadWrapper> mThreads;
    Handler mHandler;
    Runnable mWrapped;
    
    private boolean mTooSlow = false;
    
    public DownloadWrapper(Collection<DownloadWrapper> active, Handler handler, Runnable wrap) {
      mThreads = active;
      mHandler = handler;
      mWrapped = wrap;
    }
    
    public void tooSlow() {
      mTooSlow = true;
    }
    
    public void run() {
      mWrapped.run();
      
      mThreads.remove(this);
      
      if (!mTooSlow) {
        mHandler.removeCallbacks(mWakeUp);
        mHandler.post(mWakeUp);
      }
    }
  }
}

   
    
  

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