/*
* Copyright (C) 2013 www.418log.org
*
* 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.ab.bitmap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import com.ab.global.AbAppData;
import com.ab.util.AbAppUtil;
import com.ab.util.AbFileUtil;
import com.ab.util.AbStrUtil;
// TODO: Auto-generated Javadoc
/**
*
* Copyright (c) 2012 All rights reserved
* 名称：AbImageDownload.java
* 描述：线程池图片下载
* @author zhaoqp
* @date：2013-5-23 上午10:10:53
* @version v1.0
*/
public class AbImageDownloadPool{
/** The tag. */
private static String TAG = "AbImageDownloadPool";
/** The Constant D. */
private static final boolean D = AbAppData.DEBUG;
//单例对象
/** The image download. */
private static AbImageDownloadPool imageDownload = null;
/** 固定3个线程来执行任务 . */
private static int nThreads = 3;
/** The executor service. */
private ExecutorService executorService = null;
/** 下载完成后的消息句柄. */
private static Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
AbImageDownloadItem item = (AbImageDownloadItem)msg.obj;
item.listener.update(item.bitmap, item.imageUrl);
}
};
/**
* 构造图片下载器.
*
* @param nThreads the n threads
*/
protected AbImageDownloadPool(int nThreads) {
executorService = Executors.newFixedThreadPool(nThreads);
}
/**
* 单例构造图片下载器.
*
* @return single instance of AbImageDownloadPool
*/
public static AbImageDownloadPool getInstance() {
if (imageDownload == null) {
nThreads = AbAppUtil.getNumCores();
imageDownload = new AbImageDownloadPool(nThreads*3);
}
return imageDownload;
}
/**
* Download.
*
* @param item the item
*/
public void download(final AbImageDownloadItem item) {
String imageUrl = item.imageUrl;
if(AbStrUtil.isEmpty(imageUrl)){
if(D)Log.d(TAG, "图片URL为空，请先判断");
}else{
imageUrl = imageUrl.trim();
}
//从缓存中获取图片
final String cacheKey = AbImageCache.getCacheKey(imageUrl, item.width, item.height, item.type);
item.bitmap = AbImageCache.getBitmapFromCache(cacheKey);
if(item.bitmap == null){
// 缓存中没有图像，则从网络上取出数据，并将取出的数据缓存到内存中
executorService.submit(new Runnable() {
public void run() {
try {
//逻辑：判断这个任务是否有其他线程再执行，如果有等待，直到下载完成唤醒显示
Runnable runnable = AbImageCache.getRunRunnableFromCache(cacheKey);
if(runnable != null){
//线程等待通知后显示
if(D) Log.d(TAG, "等待:"+cacheKey+","+item.imageUrl);
AbImageCache.addToWaitRunnableCache(cacheKey, this);
synchronized(this){
this.wait();
}
if(D) Log.d(TAG, "我醒了:"+item.imageUrl);
//直接获取
item.bitmap = AbImageCache.getBitmapFromCache(cacheKey);
}else{
//增加下载中的线程记录
if(D) Log.d(TAG, "增加图片下载中:"+cacheKey+","+item.imageUrl);
AbImageCache.addToRunRunnableCache(cacheKey, this);
item.bitmap = AbFileUtil.getBitmapFromSDCache(item.imageUrl,item.type,item.width,item.height);
//增加到下载完成的缓存，删除下载中的记录和等待的记录，同时唤醒所有等待列表中key与其key相同的线程
AbImageCache.addBitmapToCache(cacheKey,item.bitmap);
}
} catch (Exception e) {
if(D) Log.d(TAG, "error:"+item.imageUrl);
e.printStackTrace();
} finally{
if (item.listener != null) {
Message msg = handler.obtainMessage();
msg.obj = item;
handler.sendMessage(msg);
}
}
}
});
}else{
if(D) Log.d(TAG, "从内存缓存中得到图片:"+cacheKey+","+item.bitmap);
if (item.listener != null) {
Message msg = handler.obtainMessage();
msg.obj = item;
handler.sendMessage(msg);
}
}
}
/**
* 描述：立即关闭.
*/
public void shutdownNow(){
if(!executorService.isTerminated()){
executorService.shutdownNow();
listenShutdown();
}
}
/**
* 描述：平滑关闭.
*/
public void shutdown(){
if(!executorService.isTerminated()){
executorService.shutdown();
listenShutdown();
}
}
/**
* 描述：关闭监听.
*/
public void listenShutdown(){
try {
while(!executorService.awaitTermination(1, TimeUnit.MILLISECONDS)) {
if(D) Log.d(TAG, "线程池未关闭");
}
if(D) Log.d(TAG, "线程池已关闭");
} catch (Exception e) {
e.printStackTrace();
}
}
}