android.os.Process#THREAD_PRIORITY_LOWEST源码实例Demo

/**
 * Return the appropriate thread priority for loading for a given page (we give the current
 * page much higher priority)
 */
private int getThreadPriorityForPage(int page) {
 
    int pageDiff = getWidgetPageLoadPriority(page);
    if (pageDiff <= 0) {
        return Process.THREAD_PRIORITY_LESS_FAVORABLE;
    } else if (pageDiff <= 1) {
        return Process.THREAD_PRIORITY_LOWEST;
    } else {
        return Process.THREAD_PRIORITY_LOWEST;
    }
}
 

/**
 * Return the appropriate thread priority for loading for a given page (we give the current
 * page much higher priority)
 */
private int getThreadPriorityForPage(int page) {
    // TODO-APPS_CUSTOMIZE: detect number of cores and set thread priorities accordingly below
    int pageDiff = getWidgetPageLoadPriority(page);
    if (pageDiff <= 0) {
        return Process.THREAD_PRIORITY_LESS_FAVORABLE;
    } else if (pageDiff <= 1) {
        return Process.THREAD_PRIORITY_LOWEST;
    } else {
        return Process.THREAD_PRIORITY_LOWEST;
    }
}
 

@IntRange(from = Process.THREAD_PRIORITY_FOREGROUND, to = Process.THREAD_PRIORITY_LOWEST)
int priority();
 

private void setDefaultOsPriority(int defaultOsPriority) {
    if (defaultOsPriority < Process.THREAD_PRIORITY_URGENT_AUDIO || defaultOsPriority > Process.THREAD_PRIORITY_LOWEST) {
        throw new IllegalArgumentException("Cannot set thread priority to " + defaultOsPriority);
    }
    mDefaultOsPriority = defaultOsPriority;
}
 

public void run() {
    /* 设置任务线程为后台线程，获得更少的执行机会，减少对UI渲染的影响 */
    int threadPriority = Process.getThreadPriority(Process.myTid());
    if (threadPriority != Process.THREAD_PRIORITY_LOWEST) {
        Process.setThreadPriority(Process.THREAD_PRIORITY_LOWEST);
    }
    final ImageLoadTask loadTask = seekReadyTask();
    if (loadTask == null) {
        handler.sendEmptyMessage(ACTION_LOAD_FINISH);
        return;
    }
    try {
        // 从磁盘去取
        Bitmap bitmap = DiskCache.readCache(loadTask.getKey());
        if (bitmap == null) {// 尚未缓存，从源去取
            bitmap = loadFromSource(loadTask);
        }
        if (bitmap != null) {// 取得图片成功
            // 将bitmap放入LruCache缓存列表
            memoryCache.put(loadTask.filePath, bitmap);
        }
        final Bitmap finalBitmap = bitmap;
        if (loadTask.getCallBack() != null) {
            handler.post(new Runnable() {

                @Override
                public void run() {
                    loadTask.performCallback(finalBitmap);
                }
            });
        }
    } catch (OutOfMemoryError e) {
        memoryCache.evictAll();
        System.gc();
        e.printStackTrace();
        BDebug.e(TAG, "OutOfMemoryError!!!!!!!!!!!!!!!!!!!!:" + e.getMessage());
    } finally {
        if (loadTask != null) {
            synchronized (taskList) {
                taskList.remove(loadTask);
            }
        }
    }
}
 

public ReadaheadThread() {
    mScratch = new byte[BYTES_PER_READ];
    HandlerThread handlerThread = new HandlerThread("ReadaheadThread", Process.THREAD_PRIORITY_LOWEST);
    handlerThread.start();
    mHandler = new Handler(handlerThread.getLooper(), this);
}
 

/**
 * 优先级的范围，可根据Task重要程度及工作量指定；之后根据实际情况决定是否有必要放更大
 *
 * @return
 */
@IntRange(from = Process.THREAD_PRIORITY_FOREGROUND, to = Process.THREAD_PRIORITY_LOWEST)
int priority();