I'm trying to evaluate javascript with a semaphore lock. I need to
query some web content about which context menus to show and need it
to be synchronous. When I try to acquire the semaphore the thread
locks without the javascript being evaluated and my javascript
interface method being called.
Here's my code.
private Semaphore returnSemaphore = new Semaphore(0);
private String returnValue;
public String getJSValue(String expression)
{
String code =
"javascript:_JSEval.setValue((function(){try{return "
+ expression
+ "+\"\";}catch(js_eval_err){return '';}})());";
//String code = "javascript: alert('here');";
Log.d(TAG, "eval: " + code);
this.loadUrl(code);
try {
Log.d(TAG, "eval: about to acquire semaphore, " +
returnSemaphore.availablePermits());
returnSemaphore.acquire();
Log.d(TAG, "past semaphore acquire");
return returnValue;
} catch (InterruptedException e) {
Log.e(TAG, "eval: Interrupted", e);
}
return null;
}
@SuppressWarnings("unused")
private class JSEval
{
public void setValue(String value)
{
Log.i(TAG, "eval: in set value");
//if (value != null) {
returnValue = value;
//}
returnSemaphore.release();
}
}
If I remove the semaphore acquire call, I get a result in setValue, so
I know the interface is working.
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