I was wondering how I can achieve something like an HTTPClient.
I tried WebBrowser class but it seems that the execution continues even though the URL specified has not yet loaded.
public void testWebBrowser(){
final WebBrowser b = new WebBrowser(){
#Override
public void onLoad(String url) {
BrowserComponent c = (BrowserComponent)this.getInternal();
JavascriptContext ctx = new JavascriptContext(c);
// I want this Javascript context here
}
};
// just a test URL
b.setURL("http://youtube.com");
// Suppose to get the Javascript context here though it executes without waiting for the whole page to load
}
How can I get the JS Context from within a WebBrowser context? Like a synchronous execution
WebBrowser browser = new WebBrowser();
browser.setURL("someURL");
// wait execution till the whole page in "someURL" loads till it executes the next line
BrowserComponent c = (BrowserComponent)browser.getInternal();
JavascriptContext ctx = new JavascriptContext(c);
If I understand correctly you are trying to create a scraping solution?
That's probably not the ideal approach since this will actually create a web browser which you then need to automate with JavaScript. I would suggest you create a webservice that encapsulates the HttpClient functionality and drive it with ConnectionRequest. This way when the web site changes you can just fix your server in a way seamless to your installed base.
Related
I have a WPF desktop application that is MSIX-packaged using a Windows Application Package (WAP) project. I already know how to launch my WPF desktop app the first time using URI activation, by calling AppInstance.GetActivatedEventArgs() and then analyzing the arguments:
if (activatedEventArgs.Kind == ActivationKind.Launch)
{
if (((LaunchActivatedEventArgs)activatedEventArgs).Arguments == "myactivationcode")
// .. do something
}
But if a user runs the URI activation a 2nd time, while my app is already launched, I have learned that a new instance of my app is launched. This doesn't happen with UWP apps, just desktop apps. I can kill the 2nd instance to follow a desired singleton pattern, but what I want is for the first instance of my WPF app to get some event that lets it know to come back into view.
Things I've researched that have no answers that I can see:
How to handle URI activation in a Windows Application Packaging Project?
How can I handle file activation from a WPF app which is running as UWP?
https://learn.microsoft.com/en-us/windows/uwp/launch-resume/handle-uri-activation#step-3-handle-the-activated-event
Does any such API or event exist for URI re-activation? Or do I need to do some other form of IPC, like named pipes or WCF on the 2nd instance of my app? Any help here would be greatly appreciated.
But if a user runs the URI activation a 2nd time, while my app is already launched, I have learned that a new instance of my app is launched.
Whether a second instance is launched depends on the implementation of your custom Main method.
In your second link, there is a link to blog post and a code example that demonstrates how to prevent another instance from being launched.
It uses named pipes to communicate with the already running app instance and passes a serialized IActivatedEventArgs to it:
[STAThread]
static void Main(string[] args)
{
IActivatedEventArgs activatedEventArgs = AppInstance.GetActivatedEventArgs();
using (Mutex mutex = new Mutex(false, AppUniqueGuid))
{
if (mutex.WaitOne(0, false))
{
new Thread(CreateNamedPipeServer) { IsBackground = true }
.Start();
s_application = new App();
s_application.InitializeComponent();
if (activatedEventArgs != null)
s_application.OnProtocolActivated(activatedEventArgs);
s_application.Run();
}
else if (activatedEventArgs != null)
{
//instance already running
using (NamedPipeClientStream namedPipeClientStream
= new NamedPipeClientStream(NamedPipeServerName, AppUniqueGuid, PipeDirection.Out))
{
try
{
namedPipeClientStream.Connect(s_connectionTimeout);
SerializableActivatedEventArgs serializableActivatedEventArgs = Serializer.Serialize(activatedEventArgs);
s_formatter.Serialize(namedPipeClientStream, serializableActivatedEventArgs);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, string.Empty, MessageBoxButton.OK, MessageBoxImage.Error);
}
}
}
}
}
Does any such API or event exist for URI re-activation?
No
Or do I need to do some other form of IPC, like named pipes or WCF on the 2nd instance of my app?
Yes. Again, please refer to the mentioned blog post and accompanied code sample.
I have developed a single page application with React and MobX. To get some progress information from backend code such as copying a file progress, I use Server Sent Events and EventSource at javascript code. In any browser, I can get the event messages and show progresses successfully. React gets changes from the EventSource onmessage event and renders the changes on the screen. Here is how I add EventSource to my js code. (For the ones who ask if the message format of eventsource is correct? Yes, it is. It is working on browsers.)
Code:
fetchEvents(url) {
let evtSource = new EventSource(url);
evtSource.onmessage = (message) => {
const data = JSON.parse(message.data);
//assign data to an observable variable
}
}
However, I need my single page application to be embeded in a Java application. For this, I use JavaFX WebEngine and WebView to load my React application. Every functionalities work well except Server Sent Events and EventSource messages. onmessage(), onopen(), onerror() methods are not called. Thus, I can't get the changes of data to be shown on the screen. I can't get any information via EventSource at my javascript code. Here is the JavaFX code;
Code:
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws Exception{
primaryStage.setTitle("localhost");
WebView myBrowser = new WebView();
WebEngine myWebEngine = myBrowser.getEngine();
myWebEngine.setJavaScriptEnabled(true);
myWebEngine.load("http://localhost:8080");
StackPane root = new StackPane();
root.getChildren().addAll(myBrowser, reloadButton);
primaryStage.setScene(new Scene(root, 800, 640));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Does JavaFX WebView not support EventSource and Server Sent Events? I am curious about is there any way to make SSE work in JavaFX WebView? Or are there any other possible solutions to embed my single page application in Java code with EventSource and Server Sent Events working well.
Thank you.
I have to develop a webapp for a CEF-Browser environment. There is no HTTP server available, everything will be served over file:// protocol.
When developing a Webapp nowadays one doesn't get round working with a framework like react/vue for frontend. The standard webpack build scripts of those build a bundle which only works served over HTTP.
Is it possible to configure webpacks build bundle to work on file:// or is there another way to use react or vue via file://?
I'm suggest read CEF wiki more carefully. You are especially interested in https://bitbucket.org/chromiumembedded/cef/wiki/GeneralUsage.md#markdown-header-request-handling
In short:
You can register custom scheme handler to serve resources over http+custom fake domain.
You can pack resources in zip for example if you like, or leave them at file system as is (but in that case you can expect that some funny users can edit your files, and then report back unexisting errors back to you).
Important helpers already done (but you can write own when need.)
You can... many other things.
Main thing that "file" scheme are more restricted, and for example you can't do XHR requests. But for custom handler you can. Even if dynamic loader for some reason use XHR instead DOM-based loading it will work again same as on http without touching network.
cefclient itself also has usage of custom schemes. Check URL of Tests->Other... in menu. :)
PS: Sorry that my answer doesnt have direct answer for your question. But, custom resource handling in CEF is so common, that i'm just should say about.
fddima is right - you don't need to configure your webpack (although it would be theoretically possible). Instead you can use custom scheme handler in CEF. I made it work with angular at work.
I wrote blog post on how to serve web application via 'file' protocol in CEF.
What you want to add is your scheme handler and its factory:
using System;
using System.IO;
using CefSharp;
namespace MyProject.CustomProtocol
{
public class CustomProtocolSchemeHandler : ResourceHandler
{
// Specifies where you bundled app resides.
// Basically path to your index.html
private string frontendFolderPath;
public CustomProtocolSchemeHandler()
{
frontendFolderPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "./bundle/");
}
// Process request and craft response.
public override bool ProcessRequestAsync(IRequest request, ICallback callback)
{
var uri = new Uri(request.Url);
var fileName = uri.AbsolutePath;
var requestedFilePath = frontendFolderPath + fileName;
if (File.Exists(requestedFilePath))
{
byte[] bytes = File.ReadAllBytes(requestedFilePath);
Stream = new MemoryStream(bytes);
var fileExtension = Path.GetExtension(fileName);
MimeType = GetMimeType(fileExtension);
callback.Continue();
return true;
}
callback.Dispose();
return false;
}
}
public class CustomProtocolSchemeHandlerFactory : ISchemeHandlerFactory
{
public const string SchemeName = "customFileProtocol";
public IResourceHandler Create(IBrowser browser, IFrame frame, string schemeName, IRequest request)
{
return new CustomProtocolSchemeHandler();
}
}
}
And then register it before calling Cef.Initialize:
var settings = new CefSettings
{
BrowserSubprocessPath = GetCefExecutablePath()
};
settings.RegisterScheme(new CefCustomScheme
{
SchemeName = CustomProtocolSchemeHandlerFactory.SchemeName,
SchemeHandlerFactory = new CustomProtocolSchemeHandlerFactory()
});
I'm developing my first windows phone 7 app, and I've hit a snag. basically it's just reading a json string of events and binding that to a list (using the list app starting point)
public void Load()
{
// form the URI
UriBuilder uri = new UriBuilder("http://mysite.com/events.json");
WebClient proxy = new WebClient();
proxy.OpenReadCompleted += new OpenReadCompletedEventHandler(OnReadCompleted);
proxy.OpenReadAsync(uri.Uri);
}
void OnReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
if (e.Error == null)
{
var serializer = new DataContractJsonSerializer(typeof(EventList));
var events = (EventList)serializer.ReadObject(e.Result);
foreach (var ev in events)
{
Items.Add(ev);
}
}
}
public ObservableCollection<EventDetails> Items { get; private set; }
EventDetails is my class that wraps the json string. this class has to be correct because it is an exact copy of the class used by that website internally from which the json is generated...
I get the json string correctly from the webclient call (I read the memorystream and the json is indeed there) but as soon as I attempt to deserialize the string, the application exits and the debugger stops.
I get no error message or any indication that anything happen, it just stops. This happens if I type the deserialize method into the watch window as well...
I have already tried using JSON.net in fact I thought maybe it was a problem with JSON.net so I converted it to use the native deserializer in the .net framework but the error is the same either way.
why would the application just quit? shouldn't it give me SOME kind of error message?
what could I be doing wrong?
many thanks!
Firstly, the fact that you have some string there that looks like JSON does not mean that you have a valid JSON. Try converting a simple one.
If your JSON is valid, it might be that your JSON implementation does not know how to convert a list to EventList. Give it a try with ArrayList instead and let me know.
The application closes because an unhandled exception happens. If check the App.xaml.cs file you will find the code that closes your app. What you need to do is try catch your deserialization process and handle it locally. So most likely you have some JSON the DataContractJsonSerializer does not like. I have been having issue with it deserializing WCF JSON and have had to go other routes.
You may want to check to ensure your JSON is valid, just because your website likes it does not mean it is actually valid, the code on your site may be helping to correct the issue. Drop a copy of your JSON object (the string) in http://jsonlint.com/ to see if it is valid or not. Crokford (the guy who created JSON) wrote this site to validate JSON, so I would rely on it more than your site ;) This little site has really helped me out of some issues over the past year.
I ran into this same kind of problem when trying to migrate some existing WM code to run on WP7. I believe that the WP7 app crashes whenever it loads an assembly (or class?) that references something that's not available in WP7. In my case, I think it was Assembly.Load or something in the System.IO namespace, related to file access via paths.
While your case might be something completely different, the symptoms were exactly the same.
The only thing I can recommend is to go through the JSON library and see if it's referencing base classes that are not allowed in WP7. Note that it doesn't even have to hit the line of code that's causing the issue - it'll crash as soon as it tries to hit the class that contains the bad reference.
If you can step into the JSON library, you can get a better idea of which class is causing the problem, because as soon as the code references it, the whole app will crash and the debugger will stop.
I am using GWT and Google App Engine Java for my application. I have a profile screen where
user enters profile information like name, age and address, saves it and gets success or failure message. I developed this initial application using GWT-RPC and it worked fine. I had a new requirement where I have to store image of the user. I am using BlobstoreService to store images. This has created complications in the flow. I had to use FormPanel as it is the only way to do a FileUpload in GWT. The BlobStore service servlet expects a redirect on completion. As a result it cannot now return any status back to my GWT application once the profile is saved. Is there easy to store images using GWT along with other form fields and show a status message back to user once the profile is saved.
i struggled a lot with this problem until yesterday I figured out the solution with much help from Ikai Lan's blog. Basicaly what I did is follow his steps but with a few modifications because doing it exactly how he did it did'nt work for me:
Create a form panel : set encoding multipart, method post.
Make a GWT Remote Service that just has one method:public String getUploadURL() or something like that and in the IMPL write this:
BlobstoreService service = BlobstoreServiceFactory.getBlobstoreService();
return service.createUploadUrl("/XXX/YYY");
In XXX you must put your project path, for example mine is com.fer.pyn.PictureYourNews
In YYY you must put the servlet mapping name for a new servlet that we will have to create: I put XXX = BlobUploader, I created a BlobUploader extends HttpServlet and you have to update the web.xml.
Okey, so this is the weird part that I could'nt figure out, thing is that when we make a RPC call to getUploadURL() in the remote ervice from step 2 that returns a weird addres, like: '/_ah/img/eq871HJL_bYxhWQbTeYYoA' and that is the .fromAction you have to put in your form from step one. You need to update the form's action every time so i suggest the following:
public void initBlobStoreSession()
{
imageService.getBlobStoreUploadURL(new AsyncCallback()
{
#Override
public void onSuccess(String result) {
uploadFormPanel.setAction(result);
System.out.println("Upload Form Panel Action set");
}
#Override
public void onFailure(Throwable caught) {
//oops
}
});
}
So when you submit your fromPanel, IT WILL UPLOAD THE BLOB and you dont have to do anything, the tricky part is how to get the blob:
What you need to do now is create the YYY servlet we where talking about in step 4.
In the post method, this is important:
private BlobstoreService blobService = BlobstoreServiceFactory.getBlobstoreService();
Map<String, BlobKey> blobMap = blobService.getUploadedBlobs(request);
BlobKey blobKey = blobMap.get(UPLOAD_WIDJET_NAME);
UPLOAD_WIDJET_NAME is the .setName for the FileUpload widjet.
What you are doing there is getting a key for yout BLob so you can reference it later.
Our next step is showing the uploaded image back to the GWT layer:
//In the same post method from step 7
ImagesService imagesService = ImagesServiceFactory.getImagesService();
String imageURL = imagesService.getServingUrl(blobKey);
response.sendRedirect("/XXX/YYY?imgURL="+imageURL);
Now in the get method:
String imageUrl = request.getParameter("imgURL");
response.setHeader("Content-Type", "text/html");
response.getWriter().println(imageUrl);
We are done, now you just have to
uploadFormPanel.addSubmitCompleteHandler(new SubmitCompleteHandler() {
#Override
public void onSubmitComplete(SubmitCompleteEvent event) {
uploadFormPanel.reset();
initBlobStoreSession();
String imageUrl = event.getResults();
Image image = new Image();
image.setUrl(imageUrl);
//if you are using jetty, leave this on
//or else it wont work
//Don't use GWT.getModuleBaseURL(), it doesnt
//work well in development mode
imageUrl.replace("http://0.0.0.0:8888/", "");
System.out.println(imageUrl);
final PopupPanel imagePopup = new PopupPanel(true);
imagePopup.setWidget(image);
// Add some effects
imagePopup.setAnimationEnabled(true); // animate opening the image
imagePopup.setGlassEnabled(true); // darken everything under the image
imagePopup.setAutoHideEnabled(true); // close image when the user clicks
imagePopup.center(); // center the image
}
});
check out upload4gwt which address uploading in GWT on AppEngine.
(disclosure: I created upload4gwt; it's not mature yet, however may be useful)
I had the same problem. As a workaround I'm using a redirection to a servlet that print a status message for the client to parse.
I'm passing the websafe string representation of the key to that result servlet.
That's a bit hackey, I'd like someone to come with a better answer, or explain why the blobstore servlet have to redirect.
Yeah, things get more complicated with uploads in GWT.
You can save the form data and image in separate RPCs, and either include a status message in the response to the image upload, or fire off a 3rd RPC when the form returns to get any status or metadata you need.