android alertdialog 抑制返回键

AlertDialog.Builder builder = new AlertDialog.Builder(context);
		if(icon != null){
			builder.setIcon(icon);
		}
		if(!TextUtils.isEmpty(title)){
			builder.setTitle(title);
		}
		if(!TextUtils.isEmpty(msg)){
			builder.setMessage(msg);
		}
		if(!TextUtils.isEmpty(leftButton)){
			builder.setPositiveButton(leftButton, leftOnClickListener);
		}
		if(!TextUtils.isEmpty(rightButton)){
			builder.setNegativeButton(rightButton, rightOnClickListener);
		}
		if(customerView != null){
			builder.setView(customerView);
		}
		if(onCancelListener != null){
			builder.setOnCancelListener(onCancelListener);
		}
		builder.setCancelable(canCancel); //canCancel 为true就能 抑制返回键
		return new MyAlertDialog(builder.create());