永遠不會調用WebViewClient中的onPageFinished / onPageStarted

Question

我正在為Android編寫一個小型Web應用程序，並且需要從HTML頁面獲取一些JS變量，但是從未調用setParam（final String str）中的代碼。

另外，也永遠不會調用onPageStarted（...）和onPageFinished（...）中的代碼，我想不出為什么。

void startPageParse()
{
    WebView web = new WebView(context);

    web.getSettings().setJavaScriptEnabled(true);
    web.addJavascriptInterface(new Object(){
        @JavascriptInterface
        public void setParam(final String str)
        {
            setParamFromJS(str);
        }
    }, "JSInterface");

    web.setWebViewClient(new WebViewClient(){
        @Override
        public void onPageStarted(WebView view, String url, Bitmap fav)
        {
            super.onPageStarted(view, url, fav);

            Log.v("WebCLI", "Started");
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);

            view.loadUrl("javascript:JSInterface.setParam(flashvars['pl'])");

            Log.v("WebCLI", "JSCalled");
        }
    });

    web.loadUrl(SeasonURL);
    Log.v("WebCLI", "Load called");
}

如果我在“ web.loadUrl（SeasonURL）”處設置斷點，它將起作用（！），這些行將在logcat中：

08-28 13:22:12.766    4294-4294/shirokovoi.ChromeCastSSApp W/chromium﹕ [WARNING:jni_string.cc(28)] ConvertJavaStringToUTF8 called with null string.
08-28 13:22:12.875    4294-4356/shirokovoi.ChromeCastSSApp W/chromium﹕ [WARNING:proxy_service.cc(890)] PAC support disabled because there is no system implementation
08-28 13:22:15.290    4294-4294/shirokovoi.ChromeCastSSApp V/WebCLI﹕ Load called
08-28 13:22:15.610    4294-4294/shirokovoi.ChromeCastSSApp I/Timeline﹕ Timeline: Activity_idle id: android.os.BinderProxy@425157a8 time:786230
08-28 13:22:15.625    4294-4294/shirokovoi.ChromeCastSSApp V/WebCLI﹕ Started
08-28 13:22:20.586    4294-4294/shirokovoi.ChromeCastSSApp V/WebCLI﹕ Uncaught SyntaxError: Unexpected identifier
08-28 13:22:20.586    4294-4294/shirokovoi.ChromeCastSSApp I/chromium﹕ [INFO:CONSOLE(1)] "Uncaught SyntaxError: Unexpected identifier", source: %SOMEURL% (1)
08-28 13:22:24.469    4294-4294/shirokovoi.ChromeCastSSApp V/WebCLI﹕ JSCalled

如果此活動為主要任務，則此方法也有效。

Answer 1

對於JavaScript調用，您將要對KitKat及更高版本使用其他方法。 特別是evaluateJavaScript() 。 通常，我會extend WebView並在extend WebView實現此方法，但是如果在正確的線程上運行它，則此修改后的方法應該可以使用。 您可以通過以下方法調用該方法，以適應新舊JavaScript調用：

public void injectJavaScript(WebView view, final String javascript) {

    if (javascript == null || javascript.isEmpty() || !this.isPageFinished) {
        return;
    }

    // As of KitKat, evaluateJavascript(String javascript) should be used over loadAd("javascript:(javaScriptMethod())")
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {

        String js = "javascript:" + javascript;
        view.loadUrl(js);
    } else {
        // Returns the value of the executed JavaScript as a JSON string.
        view.evaluateJavascript(javascript, new ValueCallback<String>() {
            @TargetApi(Build.VERSION_CODES.HONEYCOMB)
            @Override
            public void onReceiveValue(String stringCallback) {
                //If you'd like any response from the JS to confirm the execution
            }
        });
    }
}

因此，在onPageFinished()中調用JS的onPageFinished() ，它將類似於：

@Override
public void onPageFinished(WebView view, String url) {
    super.onPageFinished(view, url);

    String jsString = "JSInterface.setParam(flashvars['pl']);";
    injectJavaScript(view, jsString);

    Log.v("WebCLI", "JSCalled");
}