我有一个WebView正在从互联网加载一个页面。我想显示一个ProgressBar,直到加载完成。

我如何监听WebView页面加载的完成?


当前回答

谢谢你的回答。它帮助了我,但我必须根据我的需要稍加改进。我有几个页面开始和结束,所以我添加了一个定时器,检查是否在页面结束后开始一个新的页面开始。好吧,糟糕的解释。请参阅代码:)

myWebView.setWebViewClient(new WebViewClient() {
        boolean loadingFinished = true;
        boolean redirect = false;

        long last_page_start;
        long now;

        // Load the url
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (!loadingFinished) {
                redirect = true;
            }

            loadingFinished = false;
            view.loadUrl(url);
            return false;
        }

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            Log.i("p","pagestart");
            loadingFinished = false;
            last_page_start = System.nanoTime();
            show_splash();
        }

        // When finish loading page
        public void onPageFinished(WebView view, String url) {
            Log.i("p","pagefinish");
            if(!redirect){
                loadingFinished = true;
            }
            //call remove_splash in 500 miSec
            if(loadingFinished && !redirect){
                now = System.nanoTime();
                new android.os.Handler().postDelayed(
                        new Runnable() {
                            public void run() {
                                remove_splash();
                            }
                        },
                        500);
            } else{
                redirect = false;
            }
        }
        private void show_splash() {
            if(myWebView.getVisibility() == View.VISIBLE) {
                myWebView.setVisibility(View.GONE);
                myWebView_splash.setVisibility(View.VISIBLE);
            }
        }
        //if a new "page start" was fired dont remove splash screen
        private void remove_splash() {
            if (last_page_start < now) {
                myWebView.setVisibility(View.VISIBLE);
                myWebView_splash.setVisibility(View.GONE);
            }
        }

});

其他回答

我非常倾向于@NeTeInStEiN(和@polen)解决方案,但会用一个计数器来实现它,而不是多个布尔值或状态监视器(只是另一种风格,但我认为可能会共享)。它确实有一个JS的细微差别,但我觉得逻辑是更容易理解一点。

private void setupWebViewClient() {
    webView.setWebViewClient(new WebViewClient() {
        private int running = 0; // Could be public if you want a timer to check.

        @Override
        public boolean shouldOverrideUrlLoading(WebView webView, String urlNewString) {
            running++;
            webView.loadUrl(urlNewString);
            return true;
        }

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            running = Math.max(running, 1); // First request move it to 1.
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            if(--running == 0) { // just "running--;" if you add a timer.
                // TODO: finished... if you want to fire a method.
            }
        }
    });
}

对于Kotlin用户:

webView.webViewClient = object : WebViewClient() {
            override fun onPageFinished(view: WebView?, url: String?) {
                // do your logic
            }
        }

有很多方法你可以重写

这将在他开始加载页面之前被调用 (并获得与onFinished()相同的参数)

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

谢谢你的回答。它帮助了我,但我必须根据我的需要稍加改进。我有几个页面开始和结束,所以我添加了一个定时器,检查是否在页面结束后开始一个新的页面开始。好吧,糟糕的解释。请参阅代码:)

myWebView.setWebViewClient(new WebViewClient() {
        boolean loadingFinished = true;
        boolean redirect = false;

        long last_page_start;
        long now;

        // Load the url
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (!loadingFinished) {
                redirect = true;
            }

            loadingFinished = false;
            view.loadUrl(url);
            return false;
        }

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            Log.i("p","pagestart");
            loadingFinished = false;
            last_page_start = System.nanoTime();
            show_splash();
        }

        // When finish loading page
        public void onPageFinished(WebView view, String url) {
            Log.i("p","pagefinish");
            if(!redirect){
                loadingFinished = true;
            }
            //call remove_splash in 500 miSec
            if(loadingFinished && !redirect){
                now = System.nanoTime();
                new android.os.Handler().postDelayed(
                        new Runnable() {
                            public void run() {
                                remove_splash();
                            }
                        },
                        500);
            } else{
                redirect = false;
            }
        }
        private void show_splash() {
            if(myWebView.getVisibility() == View.VISIBLE) {
                myWebView.setVisibility(View.GONE);
                myWebView_splash.setVisibility(View.VISIBLE);
            }
        }
        //if a new "page start" was fired dont remove splash screen
        private void remove_splash() {
            if (last_page_start < now) {
                myWebView.setVisibility(View.VISIBLE);
                myWebView_splash.setVisibility(View.GONE);
            }
        }

});

当onpagefinished方法被调用或者进度达到100%时,渲染器将不会完成渲染,所以这两个方法都不能保证视图被完全渲染。

但是你可以从OnLoadResource方法中找出什么已经被渲染了什么还在渲染。这个方法被调用了很多次。

        @Override
        public void onLoadResource(WebView view, String url) {
            super.onLoadResource(view, url);
           // Log and see all the urls and know exactly what is being rendered and visible. If you wanna know when the entire page is completely rendered, find the last url from log and check it with if clause and implement your logic there.
            if (url.contains("assets/loginpage/img/ui/forms/")) {
                // loginpage is rendered and visible now.
               // your logic here.

            }
        }