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WebView methods on same thread error

2016-05-06 08:40 561 查看
webview之前在android 4.3的平台上是可以直接使用handler来进行通知更新使用的，但发现最近同样的代码却总是报如下的错误，也试过使用activity的 runonuithread方法，但webview何时加载完无法知道，导致进度框不知道什么时候隐藏，谷歌了一下，发现很多人遇到同样的问题，是因为android 4.4之后建议是使用
mWebView.post(new Runnable() {
@Override
public void run() {
mWebView.loadUrl(...).
}
});


上述方法来完成webview的loadurl方法，实验了一下的确可行。

WebView
methods on same thread error

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I have a android program (Java + html in a webview). I can call from the javascript to the Java code. But the other way around stopped working (after updating in eclipse).

So this is what I'm trying to do
Make a webview (worked)
calling in javascript to AndroidFunction.test(); (worked)
the java test() function call webView.loadUrl("javascript:helloBack()"); (! not working anymore)

I tried to let it work with the WebView in the MainActivity, but it didnt work.

MainActivity.java
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final WebView webView = (WebView)findViewById(R.id.webView);
webView.getSettings().setJavaScriptEnabled(true);
webView.setWebChromeClient(new WebChromeClient());
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);

javascr = new Javascript(this, webView);
webView.addJavascriptInterface(javascr, "AndroidFunction");
webView.loadUrl("file:///android_asset/www/index.html");

....
}


Javascript.java
public class Javascript {
Context cont;
WebView webView;

Javascript(Context c, WebView w) {
cont = c;
webView = w;
}

// function called in the javascript by AndroidFunction.test();
public void test() {
// Breaking point!!!
webView.loadUrl("javascript:helloBack()");
}


Error:
03-24 11:47:50.103: W/WebView(21026):   at com.android.org.chromium.base.SystemMessageHandler.handleMessage(SystemMessageHandler.java:27)
03-24 11:47:50.103: W/WebView(21026):   java.lang.Throwable: A WebView method was called on thread 'JavaBridge'. All WebView methods must be called on the same thread. (Expected Looper Looper{41ab68f8} called on Looper{41bb70a8}, FYI main Looper is Looper{41ab68f8})

03-24 11:47:50.103: W/WebView(21026):   at android.webkit.WebView.checkThread(WebView.java:2063)
03-24 11:47:50.103: W/WebView(21026):   at android.webkit.WebView.loadUrl(WebView.java:794)
03-24 11:47:50.103: W/WebView(21026):   at com.example.hellobt.Javascript.test(Javascript.java:24)

03-24 11:47:50.103: W/WebView(21026):   at com.android.org.chromium.base.SystemMessageHandler.nativeDoRunLoopOnce(Native Method)
03-24 11:47:50.103: W/WebView(21026):   at com.android.org.chromium.base.SystemMessageHandler.handleMessage(SystemMessageHandler.java:27)
03-24 11:47:50.103: W/WebView(21026):   at android.os.Handler.dispatchMessage(Handler.java:102)

03-24 11:47:50.103: W/WebView(21026):   at android.os.Looper.loop(Looper.java:137)
03-24 11:47:50.103: W/WebView(21026):   at android.os.HandlerThread.run(HandlerThread.java:61)


Thanks for the answer. I edited the function in my Javascript file like this:
private void test(final String s) {
webView.post(new Runnable() {
public void run() {
webView.loadUrl("javascript:" + s + ";");
}
});
System.out.println("javscript done..");
}


javascript 

android android-webview
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this question
edited Aug
26 '14 at 13:31

asked Mar 24 '14 at 11:07





Johan Hoeksma
4991615

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2 Answers

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The JavaScript method is executed on a background (i.e. non-UI) thread. You need to call all Android View related methods on the UI thread. You can achieve what you need with:
mWebView.post(new Runnable() {
@Override
public void run() {
mWebView.loadUrl(...).
}
});


Which will post the task to run on the UI thread.

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this answer
answered Mar 24 '14 at 13:36





ksasq
2,32011010

 
 
Bulls eye, you saved my day mate! Thanks for your short explanation and awnser. – Johan
Hoeksma Mar
25 '14 at 12:34 
 
where did you add the snippet (mWebView) to your original code? – Bowie May
28 '14 at 3:04
 
In the test() function, see my above question. – Johan
Hoeksma Aug
26 '14 at 13:32
 
What if you need to return a value? eg return webview.getUrl? stackoverflow.com/questions/29748782/…@JohanHoeksma – Suresh
Subedi Apr
20 '15 at 13:26
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a comment
up vote0down
vote
In my case nothing was shown in a WebView, so I prefer another way:
runOnUiThread(new Runnable() {
@Override
public void run() {
final WebView webView = (WebView) findViewById(R.id.map);
webView.loadDataWithBaseURL(...);
}
});


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this answer
answered Apr 8 at 9:06





CoolMind
39338

 
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