Hi Sebe
As I understand it, you want to be able to upload a file from the client and
save it on the server.
One important point -
You CANNOT read and write files in the local (that is, client) computer's general filing system
using javascript in the browser. You can only upload a file to the server, save it on the server's
filing system and then download it to the client again. If you want to do anything else you simply
can't, it would be a huge security loophole and there's enough anarchy in the web already!
I'm not very familiar with GAE but a quick scan of the docs seems to indicate that you will have to
use the BlobstoreService and upload your files to the BlobStore. One thing you *can't* seem to do is
modify the contents of the BlobStore from within the server application. It is a restriction of GAE
that you can't save files to the local filing system - if you host your own server (*not* GAE) you
can do this.
If all you want to do is to upload the file and then serve it back to your user
that seems easy.
You can also read the blob data, with the 'fetchData' method, so you if it is XML you can read it
and return (parsed if necessary) to your client maybe using some kind of XHR request like in the
code you posted.
To upload the files in your GWT app you will need to use a FileUpload widget - the example in the
javadocs is pretty comprehensive.
As I've never used GAE I can't be of any more help at this point, but others on the list may have
more relevant experience.
Regards
Alan
On 1/3/2011 7:53 AM, Sebe wrote:
Hi Alan, thanks for the response
I can not figure out is how to save content from client-side textbox
as a parameter via an XML file.
The work to be done into server's package right? I'm working with
Eclipse and I use Google Apple Engine..
You know give me a hand? Or know of a tutorial that explains how it
works? I'm desperate ..
Thanks very much
Regards
On Jan 3, 4:46 pm, "a...@mechnicality.com"<a...@mechnicality.com>
wrote:
The stack trace says it all...
com.example.foobar.client.RPCInterface.testRPC (java.lang.String)'
Threw an unexpected exception: java. lang.NoClassDefFoundError:
java.io.FileWriter is a restricted class. Please see the Google App
Engine developer's guide for more details.
You appear to have your test module in the com.example.foobar.client package.
^^^^^
This means that the GWT compiler will compile that module and it looks to me
like that contains a
reference to java.io.FileWriter - as the stack trace message says, the
developer's guide will
explain to you exactly what the problem is but the 'executive summary' is that
java.io.FileWriter
can't be used in GWT 'client' code because it can't be compiled to Javascript.
The rule in GWT is:
1. things that will only be run as javascript on the client should be in the
your.module.client.*
packages
2. things that will only be run on the server should be in the
your.module.server.* packages
3. things that will be shared by the client code should be in the
your.module.shared.* packages -
IMHO these should be kept to a minimum.
You must make sure that you have both client and shared in the
your.module.Module.gwt.xml file
Java classes used in 1. and 3. above must be restricted to those classes
supported by the GWT
compiler - see
http://code.google.com/webtoolkit/doc/latest/RefJreEmulation.html
for more details. Its all in the docs or has already been covered on this list
HTH
Alan
On 1/3/2011 6:19 AM, Sebe wrote:
Hello to all ...
I have to write an XML doc with GWT. I discovered that you can not do
client-side but it can be done with server-side.
So I setup the synchronous and asynchronous client-side:
package com.example.foobar.client ;
import com.google.gwt.user.client.rpc.RemoteService;
public interface extends RPCInterface RemoteService {
testRPC public String (String message);
}
--------------------------------------------------
-------------------------------------------------
package com.example.foobar.client ;
import com.google.gwt.user.client.rpc.AsyncCallback;
public interface RPCInterfaceAsync {
testRPC void (String message, AsyncCallback callback<String>);
}
--------------------------------------------------
-----------------------------------------------
while on the server-side I did:
import java.io.BufferedWriter;
import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.text.DateFormat;
import java.util.Date;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.example.foobar.client.RPCInterface;
public class extends RPCImpl RemoteServiceServlet implements
RPCInterface {
private static final long serialVersionUID = 1L;
testRPC public String (String message)
{
Date now = new Date ();
Dtm DateFormat.getTimeInstance String = (DateFormat.MEDIUM.) Format
(now);
try {
BufferedWriter out = new BufferedWriter (new FileWriter ("test.txt"));
out.write (message);
out.close ();
} Catch (IOException e) {
}
return "This is my message" + message;
}
}
--------------------------------------------------
-------------------------------------------------- ---------
I have not forgotten anything in the matter, because before you use
the class FileWriter and BufferedWriter the program run smoothly.
I have these errors:
ERROR] javax.servlet.ServletContext log: Exception while dispatching
incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method
'public abstract java.lang.String
com.example.foobar.client.RPCInterface.testRPC (java.lang.String)'
Threw an unexpected exception: java. lang.NoClassDefFoundError:
java.io.FileWriter is a restricted class. Please see the Google App
Engine developer's guide for more details.
at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure
(RPC.java: 378)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse
(RPC.java: 581)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall
(RemoteServiceServlet.java: 207)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost
(RemoteServiceServlet.java: 243)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost
(AbstractRemoteServiceServlet.java: 62)
at javax.servlet.http.HttpServlet.service (HttpServlet.java: 713)
at javax.servlet.http.HttpServlet.service (HttpServlet.java: 806)
at org.mortbay.jetty.servlet.ServletHolder.handle (ServletHolder.java:
511)
at org.mortbay.jetty.servlet.ServletHandler $ CachedChain.doFilter
(ServletHandler.java: 1166)
at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter
(ServeBlobFilter.java: 58)
at org.mortbay.jetty.servlet.ServletHandler $ CachedChain.doFilter
(ServletHandler.java: 1157)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter
(TransactionCleanupFilter.java: 43)
at org.mortbay.jetty.servlet.ServletHandler $ CachedChain.doFilter
(ServletHandler.java: 1157)
at com.google.appengine.tools.development.StaticFileFilter.doFilter
(StaticFileFilter.java: 122)
at org.mortbay.jetty.servlet.ServletHandler $ CachedChain.doFilter
(ServletHandler.java: 1157)
at org.mortbay.jetty.servlet.ServletHandler.handle
(ServletHandler.java: 388)
at org.mortbay.jetty.security.SecurityHandler.handle
(SecurityHandler.java: 216)
at org.mortbay.jetty.servlet.SessionHandler.handle
(SessionHandler.java: 182)
at org.mortbay.jetty.handler.ContextHandler.handle
(ContextHandler.java: 765)
at org.mortbay.jetty.webapp.WebAppContext.handle (WebAppContext.java:
418)
at com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle
(DevAppEngineWebAppContext.java: 70)
at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java: 152)
com.google.appengine.tools.development.JettyContainerService at $
ApiProxyHandler.handle (JettyContainerService.java: 349)
at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java: 152)
at org.mortbay.jetty.Server.handle (server.jar: 326)
at org.mortbay.jetty.HttpConnection.handleRequest
(HttpConnection.java: 542)
org.mortbay.jetty.HttpConnection at $ RequestHandler.content
(HttpConnection.java: 938)
at org.mortbay.jetty.HttpParser.parseNext (HttpParser.java: 755)
at org.mortbay.jetty.HttpParser.parseAvailable (HttpParser.java: 218)
at org.mortbay.jetty.HttpConnection.handle (HttpConnection.java: 404)
at org.mortbay.io.nio.SelectChannelEndPoint.run
(SelectChannelEndPoint.java: 409)
org.mortbay.thread.QueuedThreadPool at $ PoolThread.run
(QueuedThreadPool.java: 582)
Caused by: java.lang.NoClassDefFoundError: java.io.FileWriter is a
restricted class. Please see the Google App Engine developer's guide
for more details.
at com.google.appengine.tools.development.agent.runtime.Runtime.reject
(Runtime.java: 51)
at com.example.foobar.server.RPCImpl.testRPC (RPCImpl.java: 41)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke
(NativeMethodAccessorImpl.java: 39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke
(DelegatingMethodAccessorImpl.java: 25)
at java.lang.reflect.Method.invoke (Method.java: 597)
at com.google.appengine.tools.development.agent.runtime.Runtime.invoke
(Runtime.java: 100)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse
(RPC.java: 562)
... 30 more
Someone can give me a hand? Please, do not know how to do ...:(
Thanks to all
--
Alan Chaney
CTO and Founder, Mechnicality, Inc.
www.mechnicality.com
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