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The primary interface a caller must implement to receive a response from a remote procedure call.
If an RPC is successful, then onSuccess(Object) is called, otherwise
onFailure(Throwable) is called.
Each callable asynchronous method corresponds to a method in the correlated
service interface. The asynchronous method always takes an
AsyncCallback as its last parameter.
As an example, suppose the service interface defines a method called
getShapes as follows:
Shape[] getShapes(String databaseName) throws ShapeException, DbException;Its asynchronous counterpart method be declared as:
void getShapes(String databaseName, AsyncCallback callback);Note that
throws declaration is not repeated in the async
version.
A call with a typical use of AsyncCallback might look like
this:
service.getShapes(dbName, new AsyncCallback() {
public void onSuccess(Object result) {
// It's always safe to downcast to the known return type.
Shape[] shapes = (Shape[]) result;
controller.processShapes(shapes);
}
public void onFailure(Throwable caught) {
// Convenient way to find out which exception was thrown.
try {
throw caught;
} catch (InvocationException e) {
// the call didn't complete cleanly
} catch (ShapeException e) {
// one of the 'throws' from the original method
} catch (DbException e) {
// one of the 'throws' from the original method
} catch (Throwable e) {
// last resort -- a very unexpected exception
}
}
});
| Method Summary | |
void |
onFailure(java.lang.Throwable caught)
Called when an asynchronous call fails to complete normally. |
void |
onSuccess(java.lang.Object result)
Called when an asynchronous call completes successfully. |
| Method Detail |
public void onFailure(java.lang.Throwable caught)
public void onSuccess(java.lang.Object result)
Object) to the return
type of the original method for which this is a callback. Note that if the
return type of the synchronous service interface method is a primitive then
the parameter will be the boxed version of the primitive (for example, an
int return type becomes an Integer.
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