There is example for using Blob service appengine-java-sdk/demos/mediastore There is jsp file upload.jsp
If you replace <input type="submit" name="submit" value="Submit"> with <input type="submit" name="Add Image" value="Add Image"> you get this exception Uncaught exception from servlet java.lang.IllegalStateException: Must be called from a blob upload callback request. at com.google.appengine.api.blobstore.BlobstoreServiceImpl.getUploadedBlobs(BlobstoreServiceImpl.java: 128) at com.google.appengine.demos.mediastore.UploadPost.doPost(UploadPost.java: 48) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java: 511) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1166) at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java: 95) at org.mortbay.jetty.servlet.ServletHandler $CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java: 35) 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 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.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java: 238) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java: 152) at org.mortbay.jetty.Server.handle(Server.java:326) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java: 542) at org.mortbay.jetty.HttpConnection $RequestHandler.headerComplete(HttpConnection.java:923) at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java: 76) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java: 135) at com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java: 261) at com.google.apphosting.base.RuntimePb$EvaluationRuntime $2.handleRequest(RuntimePb.java:8440) at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java: 454) at com.google.net.rpc.impl.Server$RpcTask.runInContext(Server.java: 572) at com.google.tracing.TraceContext$TraceContextRunnable $1.run(TraceContext.java:448) at com.google.tracing.TraceContext.runInContext(TraceContext.java: 688) at com.google.tracing.TraceContext $AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java: 326) at com.google.tracing.TraceContext $AbstractTraceContextCallback.runInInheritedContext(TraceContext.java: 318) at com.google.tracing.TraceContext $TraceContextRunnable.run(TraceContext.java:446) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java: 1110) at java.util.concurrent.ThreadPoolExecutor $Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:636) Unexpected exception from servlet: java.lang.IllegalStateException: Must be called from a blob upload callback request -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.