方法原型

• shouldOverrideUrlLoading(WebView view, String url)

此方法已经被标记为废弃，方法的第二个参数类型为String，在Android 7.0以下系统被调用

    /**
      * @param view The WebView that is initiating the callback.
      * @param url The URL to be loaded.
      * @return {@code true} to cancel the current load, otherwise return {@code false}.
     * @deprecated Use {@link #shouldOverrideUrlLoading(WebView, WebResourceRequest)
     *   shouldOverrideUrlLoading(WebView, WebResourceRequest)} instead.
    */
   @Deprecated
   public boolean shouldOverrideUrlLoading(WebView view, String url) {
        return false;
   }

• shouldOverrideUrlLoading(WebView view, WebResourceRequest request)
  此方法的第二个参数类型为WebResourceRequest ，在Android 7.0及以上系统被调用，此方法又调用了上面的方法。

    /**
     * @param view The WebView that is initiating the callback.
     * @param request Object containing the details of the request.
     * @return {@code true} to cancel the current load, otherwise return {@code false}.
     */
    public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
        return shouldOverrideUrlLoading(view, request.getUrl().toString());
    }

因此在Android 7.0以下系统，如果我们设置了WebViewClient,只有shouldOverrideUrlLoading(WebView view, String url)方法会被调用，在Android 7.0及以上系统shouldOverrideUrlLoading(WebView view, String url)和shouldOverrideUrlLoading(WebView view, WebResourceRequest request)两个方法都会被调用。

方法说明

 /**
     * Give the host application a chance to take control when a URL is about to be loaded in the
     * current WebView. If a WebViewClient is not provided, by default WebView will ask Activity
     * Manager to choose the proper handler for the URL. If a WebViewClient is provided, returning
     * {@code true} causes the current WebView to abort loading the URL, while returning
     * {@code false} causes the WebView to continue loading the URL as usual.
     *
     * <p class="note"><b>Note:</b> Do not call {@link WebView#loadUrl(String)} with the same
     * URL and then return {@code true}. This unnecessarily cancels the current load and starts a
     * new load with the same URL. The correct way to continue loading a given URL is to simply
     * return {@code false}, without calling {@link WebView#loadUrl(String)}.
     *
     * <p class="note"><b>Note:</b> This method is not called for POST requests.
     *
     * <p class="note"><b>Note:</b> This method may be called for subframes and with non-HTTP(S)
     * schemes; calling {@link WebView#loadUrl(String)} with such a URL will fail.
  */

以上语句引自于android.webkit.WebViewClient类，翻译总结一下就是：

• 该方法给应用程序提供时机，让其控制当前的WebView是否继续加载相应的URL。
• 如果应用程序没有提供WebViewClient，默认情况下WebView会询问系统选择合适的程序处理URL。如果提供了WebViewClient，返回值为true导致当前WebView中止加载URL，返回false导致WebView继续加载当前URL。
• 继续加载给定URL的正确方法是简单地返回false，不需要调用WebView.loadUrl(String)，然后返回true。

因此阻止WebView调用系统浏览器只需要设置WebViewClient，然后返回false即可。

    webView.setWebViewClient(new WebViewClient(){
          @Override
          public boolean shouldOverrideUrlLoading(WebView view, String url) {
               return false;
          }
     });