Greetings,
I'm looking for a way to launch a GWT module when a user clicks on an XML file and have the module consume the xml data. Ideally I would like to render the XML in a rich manner and would prefer to use GWT controls instead of having to lay it out by hand via xslt + javascript.
I'm supposing one way would be to point the xml to a well known xslt that creates a simple html page that forces a redirect to the gwt module but how would I transfer the xml data to said module to allow for enhanced formatting?
Another way would be to have the process that produces the xml also include the bootstrap gwt module but it would be creating multiple bootstrap instances over time and pollute the user's directory.
The use case is that a user would run this app on their local machine which outputs an XML file. If they try and view the xml file in a browser, I'd like to have the GWT module take over and present the data accordingly. I would rather they not have to go to a page and upload the data manually.
Appreciate any ideas on the matter.
TIA
If it's something that runs on the user's machine, I would recommend to ship an executable, or generate a parallel HTML file to present the data. JavaScript run from file:/// will not be able to acces the filesystem.
Related
i'm beginner with GXT and i'm wondering if there is a way to parse a file and extract some informations without uploading it.
i created a formpanel that contains an uploadFile form but i don't know waht's next, how to get the complete path of the file so i can read/write with java io or how to retrieve the file or is there an alternatif solution, thank you.
Best Regards.
You can do it in some modern browsers using bleeding edge HTML5 apis for which you would need to use GWT JSNI code. There are no api's from GWT team as is.
HTML5 FileReader
FileReader includes four options for reading a file, asynchronously:
FileReader.readAsBinaryString(Blob|File) - The result property will contain the file/blob's data as a binary string.
FileReader.readAsText(Blob|File, opt_encoding) - The result property will contain the file/blob's data as a text string.
FileReader.readAsDataURL(Blob|File) - The result property will contain the file/blob's data encoded as a data URL.
FileReader.readAsArrayBuffer(Blob|File) - The result property will contain the file/blob's data as an ArrayBuffer object.
Example of GWT wrapper over these -
https://github.com/bradrydzewski/gwt-filesystem
You can read about it more from here - How to retrieve file from GWT FileUpload component?
IMHO you cannot read it .
Due to security reasons javascript(gwt) doesn't have access to the system drives files.
http://en.wikipedia.org/wiki/JavaScript#Security
see Opening a file in local file system in javascript
In order to get the file you need to make a server call.
Instead you can do your validation server side and throw proper messages to user.
P.S : i am not considering modern browser concept.What happens if someone opened in other than so called modern browsers?? Will the programm runs same?? Its always better to do server side validation..
The compiled JavaScript output of a GWT application is divided into various files, for instance
*.cache.html
*.gwt.rpc
hosted.html
*.nocache.js
...
I know this is done with the purpose of minimizing the size of the JavaScript, which has to be downloaded by users. For instance so that a Firefox user does not have to load the JavaScript specifically compiled for IE6.
However, especially for small GWT applications it might often be faster to download a single file of say 500kb rather than make two sequential requests first for the 5kb *.nocache.js script and then for the rest of the app (cache.html files, etc.).
This leads me to the question: Is there any framework or procedure to bundle the output of the GWT compiler into a single JavaScript file?
First, you can merge all permutations in a single file by using so-called "soft permutations".
Then, you can inline your *.nocache.js into the HTML host page (e.g. using a JSP's #include directive) to cut one additional request (you might have to add a <meta name=gwt:property content='baseUrl=myapp'> where myapp is the subfolder where the .nocache. files are located).
AFAIK that's what Google are doing for their GWT apps.
Alternatively, you can run the permutation selection on the server-side if you can totally replace the selection script (*.nocache.js) with server-side content negotiation (based on User-Agent and Accept-Language request headers for instance) that can directly generates a <script> tag for the appropriate *.cache.js file (provided you use the xsiframe linker).
AFAIK, Google use all these techniques for their GWT apps (such as Google Groups). For a small app, though, I'm not sure it's worth the effort…
Also, the last two techniques work best when your HTML host page is already dynamic and therefore already non-cacheable; otherwise you're mostly moving the problem, not solving it.
I wonder whether the sso linker can be used when you collapse all properties and soft-permutations down to a single hard permutation.
Yes, but it's maybe not something you want. See this answer: https://stackoverflow.com/a/4453716/66416 to this stackoverflow question: Merge GWT generated files.
I found another way to accomplish this: Writing a custom Linker for GWT. Two examples for linkers which compile into a single JavaScript file are:
GwtNodeLinker.java from Gwt Node project
ServerSingleScriptLinker.java from Env.js project
I am trying to program in GWT (using Eclipse and the GWT Designer). I would like to be able to take an Excel file that I have already imported into my source folder, read it, and process the data. The data will be both text and numbers, but I am comfortable doing the conversions from String to other types.
I have seen something about RequestBuilder, but I'm not sure how to use that to read Excel. Or, is there another/better way to do this?
I am willing to convert the Excel file into something like a CSV is that is necessary.
You'll probably want to do the processing in your servlet with something like
http://jexcelapi.sourceforge.net/
or
http://poi.apache.org/
I am not sure if this is clear enough to you, but it is not possible to process the excel file in GWT at least not directly.
You have to process it on the backend/server.
It can't be done on he client side because even if you put the excel file in your source folder it is not available to the GWT compiled javascript code on the client machine.
If you use Java on your backend/server you can use one of the libraries danb suggested to process it on the server and then use RequestFactory or RPC to transmit it to the client/browser for further processing/displaying.
I am looking to compile my gwt application into a single, monolithic, cross-browser compatible .html file. Ultimately, I'm trying to design an Amazon mechanical turk template via gwt. These templates must be a single .html file, since they are hosted on Amazon's machines. The .html file can reference external sources, but via absolute address only since I have no control over the file hierarchy.
It does not concern me that the monolithic file will load slower than having separate files for each browser. I am developing a fairly simple web form containing only client-side code that will be seen by very few people. Therefore, speed and cross-browser correctness are not primary concerns.
I have found that by adding the following line to my MODULE_NAME.gwt.xml I can generate a single javascript file that works exclusively for a single browser (e.g. firefox as shown below):
<set-property name="user.agent" value="gecko">
I then embed the generated code into my .html file, and it works for the single browser specified. Unfortunately, when I try opening the .html file in other browsers, the gwt generated javascript does not load.
Is there a linker command that I can add to this file that will do the trick? I tried to invoke the SingleScriptLinker via:
<add-linker name="sso" />
but got the following error:
[ERROR] The module must have exactly
one distinct permutation when using
the Single Script Linker.
I also attempted to tweak the contents of the generated javascript files in order to make them compatible enough to embed in the .html file, but the javascript generated by gwt is too confusing (even in the detailed output mode). Is there a walk-through for how to do this?
I'm using the gwt eclipse plugin on OSX.
As luck would have it, I have found a workaround soon after posting my question:
http://groups.google.com/group/Google-Web-Toolkit/browse_thread/thread/79e9634110487490
In short, the answer is to use cross-site scripting.
Add the following line to MODULE_NAME.gwt.xml:
< add-linker name="xs" />
gwt will generate a MODULE_NAME.nocache.js file as well as some MD5.cache.js files (note the MD5 files end with .js, not .html).
Compile your application
Now, put all of these .js files on server A.
Modify your MODULE_NAME.html file to contain an absolute reference to MODULE_NAME.nocache.js on server A.
Upload MODULE_NAME.html to server B.
The cross-site linker makes everything work.
If there's a way for the client side GWT code to pre-process a file on the client computer?
For example, to calculate a checksum of it before submitting the file to the server.
No it is not possible. The manipulation of the file is done by the browser, not the HTML code.
Think about it, GWT is 100% javascript. And javascript has no access whatsoever of the file in your computer. That would be an pretty big security risk! GWT "wraps" the file input box so it can be displayed inside the GWT panel. But once you press the "upload" button, the upload is done by the browser.
You could do file manipulation with another technology however. Java applets for example. But that is outside of GWT area...
Using GWT, there is no way to read files on the client side yet. However, in HTML5, you can read files without uploading to a server using the "File API".
Links are provided below.
File API tutorial on html5rocks.com
Example of how to use File API in GWT via JSNI
I'm pretty sure that because GWT code compiles to pure JavaScript, there isn't a way without requiring some third-party browser plugin.
Do you mean from an <input type="file"...> file upload field in a form?
The short answer is no-- file uploads are handled by the browser, and are sent directly to the server (as an ENCODING_MULTIPART POST). And security restrictions on JavaScript mean there's no way to workaround that restriction.