Android监听返回按钮事件

用户在点击手机的返回按钮时，默认是推出当前的activty，但是有时用户不小心按到返回，所以需要给用户一个提示，这就需要重写onkeydown事件，实现的效果如下：

实现代码如下：

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
    protected void dialog() {
        AlertDialog.Builder builder = new Builder(HanderTestActivty.this);
        builder.setMessage("确定要退出吗?");
        builder.setTitle("提示");
        builder.setPositiveButton("确认",
                new Android.content.DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                        HanderTestActivty.this.finish();
                    }
                });
        builder.setNegativeButton("取消",
                new android.content.DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
        builder.create().show();
    }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
            dialog();
            return false;
        }
        return false;
    }