WebViewPool, Last html page show before new url when reuse WebView from WebViewPool

Issue

There is a WebViewPool,when Activity/Fragment is destoryed,webview will be reset and add to the WebViewPool.

The following is the code of WebViewPool:

public class WebViewPool {

  private static volatile WebViewPool sINSTANCE;
  private int mMaxSize;

  private List<WebView> mAvailableList;
  private List<WebView> mInUsedList;
  private IWebViewPoolFactory mFactory;

  private WebViewPool() {

  }

  public static WebViewPool getInstance() {
    if (sINSTANCE == null) {
      synchronized (WebViewPool.class) {
        if (sINSTANCE == null) {
          sINSTANCE = new WebViewPool();
        }
      }
    }
    return sINSTANCE;
  }

  public void init(IWebViewPoolFactory factory,boolean lazy) {
    init(2, factory,lazy);
  }

  public void init(int maxSize, IWebViewPoolFactory factory,boolean lazy) {
    mMaxSize = maxSize;
    mFactory = factory;
    mAvailableList = new ArrayList<>(maxSize);
    mInUsedList = new ArrayList<>(maxSize);
    if (!lazy) {
      create();
    }
  }


  private synchronized void create() {
    if (mFactory == null) {
      return;
    }
    for (int i = 0; i < mMaxSize; i++) {
      WebView webView = mFactory.create(new MutableContextWrapper(APP.getApplicationContext()));
      mAvailableList.add(webView);
    }
  }

  /**
   * get webview form pool
   * @param context
   * @return
   */
  public synchronized WebView getWebView(Context context) {
    if(!(context instanceof Activity)){
      throw new IllegalStateException("Context must be Activity");
    }
    WebView webView = null;
    if (mAvailableList.size() > 0) {
      webView = mAvailableList.remove(0);

    } else {
      if (mFactory != null) {
        webView = mFactory.create(new MutableContextWrapper(APP.getApplicationContext()));
      }
    }
    if (webView != null) {
      ((MutableContextWrapper) webView.getContext()).setBaseContext(context);
      mInUsedList.add(webView);
    }
    return webView;
  }

  /**
   * reset/destroy webview when activity/fragemnt is destroyed
   * @param webView
   */
  public synchronized void restWebView(WebView webView) {
    if (webView == null || mFactory == null) {
      return;
    }
    mFactory.reset(webView);
    ((MutableContextWrapper) webView.getContext()).setBaseContext(APP.getApplicationContext());
    if (mInUsedList.contains(webView)) {
      mInUsedList.remove(webView);
      if (mAvailableList.size() < mMaxSize) {
        mAvailableList.add(webView);
      } else {
        mFactory.destroy(webView);
      }
    } else {
      mFactory.destroy(webView);
    }
  }
}

the following is some code of reset function:

    public void reset(WebView webView) {
        if(webView==null){
            return;
        }
        ViewParent viewParent = webView.getParent();
        if (viewParent!=null) {
            ((ViewGroup)viewParent).removeView(webView);
        }
        webView.stopLoading();
        webView.clearCache(false);
        webView.loadUrl("about:blank");
        new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
            @Override
            public void run() {
                webView.clearHistory();
            }
        }, 1000);
    }

But when reuse the webview,last html page show first before new url sometimes.It doesn't happened everytime. I searched in Google, but not work.Does anyone know the reason? Thank you!

Solution

This problem is solved finally! The reason is that add the reseted WebView to available list while about:blank is not loaded so that clearHistory() doesn't work.

So, reset the webview but do not add to available list when activity/fragment is destroyed, call clearHistory() at onPageFinished() when url is about:blank:

@Override
public void onPageFinish(String url, boolean success) {
    if("about:blank".equals(url)){
        webView.clearHistory();
        //then add the webview to available list;
     }
}

Answered By - zys