从 AsyncTask 显示 Toast 直到事件发生

Question

我想使用 Toast 显示 "Connecting ..." 直到 设备连接到新网络（更具体地说，当获得 IP 地址时，请参阅 while 循环在下面的 doInBackground 中）。我正在使用 AsyncTask 连接到网络，但是如果我将 Toast.makeText(...).show() 放在 onProgressUpdate() 中，toast 调用将堆叠并最终以比预期更长的时间显示文本。我的连接 class:

public class Connect extends AsyncTask<Object,Void,Void>{
    private static final String TAG="sure2015test";
    private Context context;
    private Network network;
    @Override
    protected Void doInBackground(Object... params) {

        this.network=(Network)params[0];
        this.context=(Context) params[1];
        final WifiConfiguration conf = new WifiConfiguration();
        conf.SSID = "\"" + network.ssid + "\"";
        if(network.password!=null){
            conf.preSharedKey = "\""+ network.password +"\"";
        }
        else{
            conf.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
        }

        if(network.manager.addNetwork(conf)==-1){
            Log.i(TAG, "Add network fail");
        }
        List<WifiConfiguration> configs = network.manager.getConfiguredNetworks();
        for (WifiConfiguration i : configs) {
            if (i.SSID != null && i.SSID.equals("\"" + network.ssid + "\"")) {
                network.manager.disconnect();
                if(network.manager.enableNetwork(i.networkId, true)==false){
                    Log.i(TAG,"Enable Network fail ");
                }
                if(network.manager.reconnect()==false) {
                    Log.i(TAG, "Reconnect fail");
                }
            }
        }
        WifiInfo info=network.manager.getConnectionInfo();
        while((info.getIpAddress())==0){
            //Wait until non-zero IP address (once a non-zero ip address is obtained, you are connected to the network)
            //Tried to use NetworkInfo.DetailedState to check if it was CONNECTED
            //However the api method said it remained in OBTAINING_IPADDR state even after it obtained an ip (must be bug)
            info=network.manager.getConnectionInfo();
            publishProgress();
            Log.i(TAG,"IP "+info.getIpAddress());
            try{
                Thread.sleep(100);
            }
            catch(InterruptedException e){
                Log.i(TAG,"Interrupted exception");
            }
        }
        return null;
    }


    @Override
    protected void onProgressUpdate(Void... values) {
        Toast.makeText(context, "Connecting ...", Toast.LENGTH_SHORT).show();
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        Toast.makeText(context,"Connected",Toast.LENGTH_SHORT).show();
        Intent newActivity = new Intent(context, Device.class);
        newActivity.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        newActivity.putExtra("Device", network.ssid);
        context.startActivity(newActivity);
        super.onPostExecute(aVoid);
    }
}

Answer 1

我建议使用 ProgressDialog 而不是 Toast。您可以在运行之前显示它 AsyncTask 并隐藏它 onPostExecute。它看起来像.-

ProgressDialog dialog = ProgressDialog.show(CurrentActivity.this, "", "Connecting...", true, false);

[...]

dialog.dismiss();

顺便说一句，不要忘记将字符串文字放入 Strings 资源文件中 :)

Answer 2

吐司不是显示工作进度的好习惯。 Toast 旨在显示次要信息和快速信息（例如，在您的情况下是显示设备已连接），但我认为最好在布局中实现 ProgressBar 并将其设置为可见，同时 AsyncTask执行 doInBackground 并在 onPostExecute.

中设置为不可见

Answer 3

如果你需要在另一个线程中显示 Toast，也在 doInBackground(Object...params) 中，你可以使用：

YourActivity.this.runOnUiThread(new Runnable() {
    public void run() {
        //put here your thread
    }
});

但是，在这种情况下，您需要获取上下文。我用静态变量来做。但不要忘记，Toast 只出现很短的时间，您无法管理它。如果你需要一直显示消息，你可以使用 ProgressDialog

从 AsyncTask 显示 Toast 直到事件发生

Display Toast from AsyncTask until event occurs

android

toast

android-asynctask