CODEWITHSUNDEEP
google-app-engineblobstore
Sayyam
Sayyam

Reputation: 959

How can I retrieve a blobstore file by name

I wrote the following code:

                     FileService fileService = FileServiceFactory
                 .getFileService();

                 // Create a new Blob file with mime-type "text/plain"
                 AppEngineFile file = fileService.createNewBlobFile(
                 "image/jpeg", name);

                 if(null!=file)
                 log.warn(file.toString());

                 FileReadChannel readChannel =
                 fileService.openReadChannel(
                 file, true);

                 // Again, different standard Java ways of reading from
                 // the
                 // channel.
                 BufferedReader reader = new BufferedReader(Channels
                 .newReader(readChannel, "UTF8"));
                 String line = reader.readLine();

                 resp.setContentType("text/plain");
                 resp.getWriter().println(line);

                 readChannel.close();

But unfortunately, it gives me the following exception:

Uncaught exception from servlet com.google.appengine.api.files.FinalizationException at com.google.appengine.api.files.FileServiceImpl.translateException(FileServiceImpl.java:597) at com.google.appengine.api.files.FileServiceImpl.makeSyncCall(FileServiceImpl.java:574) at com.google.appengine.api.files.FileServiceImpl.open(FileServiceImpl.java:496) at com.google.appengine.api.files.FileServiceImpl.openForRead(FileServiceImpl.java:456) at com.google.appengine.api.files.FileServiceImpl.openForRead(FileServiceImpl.java:447) at com.google.appengine.api.files.FileServiceImpl.openReadChannel(FileServiceImpl.java:202) at com.myfileshost.MyfileshostServlet.doGet(MyfileshostServlet.java:362) at javax.servlet.http.HttpServlet.service(HttpServlet.java:617) 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$CachedChain.doFilter(ServletHandler.java:1166) at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:102) at org.mortbay.jetty.servlet.ServletHandler$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:249) 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$RequestHandler.headerComplete(HttpConnection.java:923) at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:135) at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:446) at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:449) at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:455) at com.google.tracing.TraceContext.runInContext(TraceContext.java:695) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:333) at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:325) at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:453) at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251) at java.lang.Thread.run(Thread.java:679)

Upvotes: 0

Views: 822

Answers (1)

Peter Knego
Peter Knego

Reputation: 80340

When a file is created via a GAE FileService it must be finalized before it can be read.

Javadoc of openReadChannel(..) clearly states that this method throws FinalizationException if file is not finalized.

Here is a full example on how to create file, finalize it and then read from it: https://developers.google.com/appengine/docs/java/blobstore/overview#Writing_Files_to_the_Blobstore

Upvotes: 1

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