Question

我目前有Android活动管理一些本地存储的RSS源。在此活动中，这些订阅源通过私有类在其自己的线程中更新。我还试图包含一个“更新”图标，该图标在此线程运行时以RotateAnimation旋转。

动画本身可以工作，但在线程运行时不起作用，尽管日志条目表明正在执行代码。我怀疑这是由于线程不完全安全，占用了大部分CPU时间。但是，我想知道是否有更好的方法来实现这一目标。

按下按钮调用函数updateAllFeeds()。这是相关的代码：

/**
 * Gets the animation properties for the rotation
 */
protected RotateAnimation getRotateAnimation() {
    // Now animate it
    Log.d("RSS Alarm", "Performing animation");
    RotateAnimation anim = new RotateAnimation(359f, 0f, 16f, 21f);
    anim.setInterpolator(new LinearInterpolator());
    anim.setRepeatCount(Animation.INFINITE);
    anim.setDuration(700);
    return anim;
}

/**
 * Animates the refresh icon with a rotate
 */
public void setUpdating() {
    btnRefreshAll.startAnimation(getRotateAnimation());
}

/**
 * Reverts the refresh icon back to a still image
 */
public void stopUpdating() {
    Log.d("RSS Alarm", "Stopping animation");
    btnRefreshAll.setAnimation(null);
    refreshList();
}

/**
 * Updates all RSS feeds in the list
 */
protected void updateAllFeeds() {
    setUpdating();
    Updater updater = new Updater(channels);
    updater.run();

}

/**
 * Class to update RSS feeds in a new thread
 * @author Michael
 *
 */
private class Updater implements Runnable {

    // Mode flags
    public static final int MODE_ONE = 0;
    public static final int MODE_ALL = 1;

    // Class vars
    Channel channel;
    ArrayList<Channel> channelList;
    int mode;

    /**
     * Constructor for singular update
     * @param channel
     */
    public Updater(Channel channel) {
        this.mode = MODE_ONE;
        this.channel = channel;
    }

    /**
     * Constructor for updating multiple feeds at once
     * @param channelList The list of channels to be updated
     */
    public Updater(ArrayList<Channel> channelList) {
        this.mode = MODE_ALL;
        this.channelList = channelList;
    }

    /**
     * Performs all the good stuff
     */
    public void run() {
        // Flag for writing problems
        boolean write_error = false;

        // Check if we have a singular or list
        if(this.mode == MODE_ONE) {
            // Updating one feed only
            int updateStatus = channel.update(getApplicationContext());

            // Check for error
            if(updateStatus == 2) {
                // Error - show dialog
                write_error = true;
            }
        }
        else {
            // Iterate through all feeds
            for(int i = 0; i < this.channelList.size(); i++) {
                // Update this item
                int updateStatus = channelList.get(i).update(getApplicationContext());                
                 if(updateStatus == 2) {
                     // Error - show dialog
                     write_error = true;
                 }
            }
        }

        // If we have an error, show the dialog
        if(write_error) {
            runOnUiThread(new Runnable(){
                public void run() {  
                    showDialog(ERR_SD_READ_ONLY);
                }
             });
        }

        // End updater
        stopUpdating();
    }   // End run()
}   // End class Updater

（我知道updateStatus == 2位是不好的做法，这是我打算收拾的下一件事之一。）

非常感谢任何帮助，非常感谢提前。

Answer 1

在单独的线程中运行updater runnable。进行以下更改。

protected void updateAllFeeds() {
    setUpdating();
    new Thread( new Updater(channels)).start();
}

在stopUpdating()阻止中致电runOnUiThread。

private class Updater implements Runnable {
    .........
    .........    
    .........
    public void run() {
        .........
        .........

        // End updater
        runOnUiThread(new Runnable(){
                public void run() {  
                     stopUpdating();
                }
             });

    }   // End run()
}   // End class Updater

Answer 2

将影响用户界面的任何内容移至自己的Runnable，然后使用按钮发布

btnRefreshAll.post(new StopUpdating());

Answer 3

昨晚我设法使用Android的AsyncTask课程来完成这项工作。它实现起来非常简单，但缺点是我必须编写一个类来更新单个feed，另一个用于更新所有feed。以下是一次更新所有Feed的代码：

private class MassUpdater extends AsyncTask<ArrayList<Channel>, Void, Void> {

    @Override
    protected Void doInBackground(ArrayList<Channel>... channels) {
        ArrayList<Channel> channelList = channels[0];

        // Flag for writing problems
        boolean write_error = false;

            // Iterate through all feeds
            for(int i = 0; i < channelList.size(); i++) {
                // Update this item
                int updateStatus = channelList.get(i).update(getApplicationContext());                
                 if(updateStatus == FileHandler.STATUS_WRITE_ERROR) {
                     // Error - show dialog
                     write_error = true;
                 }
            }


        // If we have an error, show the dialog
        if(write_error) {
            runOnUiThread(new Runnable(){
                public void run() {  
                    showDialog(ERR_SD_READ_ONLY);
                }
             });
        }
        return null;
    }

    protected void onPreExecute() {
        btnRefreshAll.setAnimation(getRotateAnimation());
        btnRefreshAll.invalidate();
        btnRefreshAll.getAnimation().startNow();
    }

    protected void onPostExecute(Void hello) {
        btnRefreshAll.setAnimation(null);
        refreshList();
    }
}

感谢您的回答。 userSeven7s的回复也很有道理，所以如果我遇到AsyncTask的任何问题，我可能会将其用作备份。

Android：运行线程阻止动画启动

3 个答案: