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?
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
我把NeTeInStEiN的代码简化成这样:
mWebView.setWebViewClient(new WebViewClient() {
private int webViewPreviousState;
private final int PAGE_STARTED = 0x1;
private final int PAGE_REDIRECTED = 0x2;
@Override
public boolean shouldOverrideUrlLoading(WebView view, String urlNewString) {
webViewPreviousState = PAGE_REDIRECTED;
mWebView.loadUrl(urlNewString);
return true;
}
@Override
public void onPageStarted(WebView view, String url, Bitmap favicon) {
super.onPageStarted(view, url, favicon);
webViewPreviousState = PAGE_STARTED;
if (dialog == null || !dialog.isShowing())
dialog = ProgressDialog.show(WebViewActivity.this, "", getString(R.string.loadingMessege), true, true,
new OnCancelListener() {
@Override
public void onCancel(DialogInterface dialog) {
// do something
}
});
}
@Override
public void onPageFinished(WebView view, String url) {
if (webViewPreviousState == PAGE_STARTED) {
dialog.dismiss();
dialog = null;
}
}
});
这很容易理解,OnPageFinished如果之前的回调是onpagstarted,所以页面是完全加载的。
我发现了一个优雅的解决方案,虽然没有严格测试:
public void onPageFinished(WebView view, String url) {
super.onPageFinished(view, url);
if (webView.getProgress() == 100) {
progressBar.setVisibility(View.GONE);
webView.setVisibility(View.VISIBLE);
}
}
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
这里有一个方法,它允许你注册一个Runnable,一旦一个特定的网页地址完成加载就会被执行。我们将每个可运行对象与Map中对应的URL字符串相关联,并使用WebView的getOriginalUrl()方法来选择适当的回调。
package io.github.cawfree.webviewcallback;
/**
* Created by Alex Thomas (@Cawfree), 30/03/2017.
**/
import android.net.http.SslError;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.webkit.SslErrorHandler;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import java.util.HashMap;
import java.util.Map;
/** An Activity demonstrating how to introduce a callback mechanism into Android's WebView. */
public class MainActivity extends AppCompatActivity {
/* Member Variables. */
private WebView mWebView;
private Map<String, Runnable> mCallbackMap;
/** Create the Activity. */
@Override protected final void onCreate(final Bundle pSavedInstanceState) {
// Initialize the parent definition.
super.onCreate(pSavedInstanceState);
// Set the Content View.
this.setContentView(R.layout.activity_main);
// Fetch the WebView.
this.mWebView = (WebView)this.findViewById(R.id.webView);
this.mCallbackMap = new HashMap<>();
// Define the custom WebClient. (Here I'm just suppressing security errors, since older Android devices struggle with TLS.)
this.getWebView().setWebViewClient(new WebViewClient() {
/** Handle when a request has been launched. */
@Override public final void onPageFinished(final WebView pWebView, final String pUrl) {
// Determine whether we're allowed to process the Runnable; if the page hadn't been redirected, or if we've finished redirection.
if(pUrl.equals(pWebView.getOriginalUrl())) {
// Fetch the Runnable for the OriginalUrl.
final Runnable lRunnable = getCallbackMap().get(pWebView.getOriginalUrl());
// Is it valid?
if(lRunnable != null) { lRunnable.run(); }
}
// Handle as usual.
super.onPageFinished(pWebView, pUrl);
}
/** Ensure we handle SSL state properly. */
@Override public final void onReceivedSslError(final WebView pWebView, final SslErrorHandler pSslErrorHandler, final SslError pSslError) { pSslErrorHandler.proceed(); }
});
// Assert that we wish to visit Zonal's website.
this.getWebView().loadUrl("http://www.zonal.co.uk/");
// Align a Callback for Zonal; this will be serviced once the page has loaded.
this.getCallbackMap().put("http://www.zonal.co.uk/", new Runnable() { @Override public void run() { /* Do something. */ } });
}
/* Getters. */
public final WebView getWebView() {
return this.mWebView;
}
private final Map<String, Runnable> getCallbackMap() {
return this.mCallbackMap;
}
}
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.
}
}
});
}