显示 ProgressDialog 时 onBackPressed() 不会触发

Question

我尝试了很多方法来在显示 progressDialog 时触发 backPressed() 事件。但没有一个有效。如果我提供 progDialog.setcancelable(true); 我可以关闭 progressDialog 但仍然不会触发 onBackPressed() 。

Answer 1

当 ProgressDialog 处于活动状态时，如果您按返回键执行您自己的操作，您必须将 setOnCancelListener 设置为 ProgressDialog。
在 onCancel() 方法示例中编写您的逻辑，您在 onBackPressed() 事件中编写的整个逻辑，您必须在此处编写这些内容。

示例代码

import android.app.Activity;

import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnCancelListener;

import android.os.Bundle;

import android.view.KeyEvent;
import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

public class CancelProgressDialog extends Activity {

    ProgressDialog myProgressDialog = null;

    @Override
    public void onCreate(Bundle icicle) {

        super.onCreate(icicle);

        /* Create a very simple button */

        Button b = new Button(this);

        this.setContentView(b);

        b.setText("Show ProgressBar...");

        b.setOnClickListener(myProgressBarShower);

    }


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        System.out.println("...any key is pressed....");
        if (keyCode == KeyEvent.KEYCODE_BACK)
        {
            System.out.println("...BackButton is pressed...");
            if( (myProgressDialog!= null) && myProgressDialog.isShowing()){
                myProgressDialog.dismiss();
            }
        }
        return super.onKeyDown(keyCode, event);
    }

    /** OnClickListener that fakes some work to be done. */

    OnClickListener myProgressBarShower = new OnClickListener() {

        // @Override

        public void onClick(View arg0) {

            // Display an indeterminate Progress-Dialog

            myProgressDialog = ProgressDialog.show(CancelProgressDialog.this,

            "Please wait...", "Doing Extreme Calculations...", true);
            myProgressDialog.setOnCancelListener(new OnCancelListener() {

                public void onCancel(DialogInterface arg0) {
                    // TODO Auto-generated method stub
                    System.out.println("...cancel button is pressed");
//                  perform your task here
                }
            });
            myProgressDialog.setCancelable(true);



        }



    };

}

谢谢
迪帕克