如何在关闭警报对话框之前关闭SoftInputKeyboard

AlertDialog alertDialog = new AlertDialog.Builder(this)
        .setTitle("警告")
        .setMessage("确定要关闭吗？")
        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                // 关闭软键盘
                Window window = getWindow();
                InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                if (imm.isActive()) {
                    imm.hideSoftInputFromWindow(window.getDecorView().getWindowToken(), 0);
                }
                // 关闭对话框
                dialog.dismiss();
            }
        })
        .setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                // 关闭对话框
                dialog.dismiss();
            }
        })
        .create();
alertDialog.show();