URL更改或onStart活动

Question

我一直在尝试将SwipeRefreshLayout与WebView一起使用。为了分隔滚动触发器（用于垂直滚动页面）和SwipeRefreshLayout，我尝试使用ViewTreeObserver来检查页面滚动是否仅在顶部，然后SwipeRefreshTrigger被调用，否则用户应该能够在页面中上下滚动。当应用程序启动时，一切都很好，用户可以在页面上上下滚动，并且SwipeRefreshLayout仅在用户在页面顶部时尝试时才触发。用户关闭应用程序，应用程序开始在后台运行。之后，当用户再次打开应用程序时，WebView布局会显示最后一个打开的页面。然后，用户无法滚动页面（仅SwipeRefreshLayout起作用）。有时，即使在某些URL更改或在页面中打开某些菜单之后，也会发生这种情况（如果需要，可以使用应用程序显示响应式网页）。

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private WebView mWebView;

    private ViewTreeObserver.OnScrollChangedListener mOnScrollChangedListener;

    SwipeRefreshLayout mySwipeRefreshLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mySwipeRefreshLayout = (SwipeRefreshLayout) this.findViewById(R.id.swipeContainer);

        String URL = "www.mysite.com";
        mWebView = (WebView) findViewById(R.id.myWebView);
        WebSettings webSettings = mWebView.getSettings();

        mWebView.loadUrl(URL);
        webSettings.setJavaScriptEnabled(true);
        webSettings.setDomStorageEnabled(true);
        mWebView.setVerticalScrollBarEnabled(true);
        mWebView.setWebChromeClient(new WebChromeClient());

        mWebView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
            @Override
            public void onScrollChanged() {
                if (mWebView.getScrollY() == 0) {
                    mySwipeRefreshLayout.setEnabled(true);
                } else {
                    mySwipeRefreshLayout.setEnabled(false);
                }
            }
        });

        // I override my URL loading, if this matters.
        mWebView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {

                if (url.startsWith("tel:"))
                {
                    Intent intent = new Intent(Intent.ACTION_DIAL, Uri.parse(url));
                    startActivity(intent);
                    return true;
                }
                view.loadUrl(url);
                return true;
            }
        });

        mySwipeRefreshLayout.setOnRefreshListener(
                new SwipeRefreshLayout.OnRefreshListener() {
                    @Override
                    public void onRefresh() {
                        mWebView.reload();
                        if (null != mySwipeRefreshLayout) {
                            mySwipeRefreshLayout.setRefreshing(false);
                        }
                    }
                }
        );
    }

    @Override
    public void onStart() {
        super.onStart();
        // I added ViewTreeObserver here too, but no luck by doing this
        mySwipeRefreshLayout.getViewTreeObserver().addOnScrollChangedListener(mOnScrollChangedListener =
                new ViewTreeObserver.OnScrollChangedListener() {
                    @Override
                    public void onScrollChanged() {
                        if (mWebView.getScrollY() == 0)
                            mySwipeRefreshLayout.setEnabled(true);
                        else
                            mySwipeRefreshLayout.setEnabled(false);

                    }
                });
    }

    @Override
    public void onStop() {

        mySwipeRefreshLayout.getViewTreeObserver().removeOnScrollChangedListener(mOnScrollChangedListener);
        super.onStop();
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_main">

<android.support.v4.widget.SwipeRefreshLayout
    android:id="@+id/swipeContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipToPadding="false"
        android:fillViewport="true">
        <WebView
            android:id="@+id/myWebView"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </android.support.v4.widget.NestedScrollView>

</android.support.v4.widget.SwipeRefreshLayout>

</RelativeLayout>