无法在Android Studio的webView中使用缩放功能

webView.getSettings().setSupportZoom(true); // 启用缩放功能
webView.getSettings().setBuiltInZoomControls(true); // 显示缩放控件
webView.getSettings().setDisplayZoomControls(false); // 隐藏原生的缩放控件

button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        webView.zoomIn(); // 放大webView内容
    }
});

webView.setOnTouchListener(new View.OnTouchListener() {
    private float scaleFactor = 1.0f;
    private float lastScaleFactor = 1.0f;

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if (event.getPointerCount() > 1) {
            // 多指触控时进行缩放操作
            switch (event.getAction()) {
                case MotionEvent.ACTION_POINTER_DOWN:
                    lastScaleFactor = scaleFactor;
                    break;
                case MotionEvent.ACTION_MOVE:
                    scaleFactor = lastScaleFactor * event.getScaleFactor();
                    webView.setInitialScale((int) (scaleFactor * 100));
                    break;
            }
        }
        return false;
    }
});