java - 在Google应用程序引擎中如何删除最初使用FileService存储的文件

Question

我正在尝试删除使用 FileService 存储的文件。在少数情况下，删除会成功，但在大多数情况下不会成功，而且我还没有找到模式。我在本地服务器上的 Windows 7 上使用 Eclipse。我怎样才能删除该文件？

编辑:当我上传到应用程序引擎时它会起作用。

这是存储代码:

try 
                            {
                                FileService fileService = FileServiceFactory.getFileService();
                                AppEngineFile file = fileService.createNewBlobFile(content_type, fileName);
                                boolean lock = true;
                                FileWriteChannel writeChannel = fileService.openWriteChannel(file, lock);
                                byte[] b1 = new byte[BUFFER_SIZE];
                                int readBytes1;
                                while ((readBytes1 = is.read(b1)) != -1) 
                                {
                                    writeChannel.write(ByteBuffer.wrap(b1, 0, readBytes1));
                                }

                                writeChannel.closeFinally();

                                blobKey = fileService.getBlobKey(file);
                                item_image_blob_key = blobKey.getKeyString();
                            } 
                            catch (Exception e) 
                            {
                                System.out.println(e.getLocalizedMessage());
                                e.printStackTrace(response.getWriter());
                            }

这是删除尝试:

@Override
public long deleteItem(Long id) 
{
    System.out.println(LOG +"   Trying to delete item with this id: " + id);

    Key parent = KeyFactory.createKey("MffItems", MFF_ITEM_ROOT_KEY);
    Key key = KeyFactory.createKey(parent, "Item", id);

    try
    {
        Entity e = datastore.get(key); 
        String image_key = (String) e.getProperty("image_blob_key");

        BlobKey blobKey = new BlobKey(image_key);
        final AppEngineFile f = fileService.getBlobFile(blobKey);

        if(f.isReadable())
        {
            System.out.println(LOG + "  file is readable");

            if(f.hasFinalizedName())
            {
                System.out.println(LOG + "  file has finalized name:  " + f.getNamePart());

                fileService.delete(f); // Problematic line
                datastore.delete(key);
                return id;
            }
        }
    }
    catch(Exception e)
    {
        System.out.println(LOG + "   " + e.toString() + "  " + e.getMessage());
    }

    // TODO Auto-generated method stub
    return -1;
}

这是我收到的错误:

I_MFF_ItemService Trying to delete item with this id: 2 I_MFF_ItemService file is readable I_MFF_ItemService file has finalized name: TXP5bVCmBVugDOxktBGv_w Jun 30, 2013 12:24:03 PM com.google.appengine.api.blobstore.dev.LocalBlobstoreService$1 run WARNING: Could not delete blob: java.io.IOException: Could not delete: C:\Users\Gideon\Desktop\dev\workspace2\ItemManager1.41\war\WEB-INF\appengine-generated\TXP5bVCmBVugDOxktBGv_w at com.google.appengine.api.blobstore.dev.FileBlobStorage.deleteBlob(FileBlobStorage.java:79) at com.google.appengine.api.blobstore.dev.LocalBlobstoreService$1.run(LocalBlobstoreService.java:153) at java.security.AccessController.doPrivileged(Native Method) at com.google.appengine.api.blobstore.dev.LocalBlobstoreService.deleteBlob(LocalBlobstoreService.java:146) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at com.google.appengine.tools.development.ApiProxyLocalImpl$AsyncApiCall.callInternal(ApiProxyLocalImpl.java:521) at com.google.appengine.tools.development.ApiProxyLocalImpl$AsyncApiCall.call(ApiProxyLocalImpl.java:475) at com.google.appengine.tools.development.ApiProxyLocalImpl$AsyncApiCall.call(ApiProxyLocalImpl.java:452) at java.util.concurrent.Executors$PrivilegedCallable$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.util.concurrent.Executors$PrivilegedCallable.call(Unknown Source) at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)

I_MFF_ItemService java.io.IOException: Blobstore failure Blobstore failure Jun 30, 2013 12:24:27 PM com.google.appengine.api.datastore.dev.LocalDatastoreService$PersistDatastore persist INFO: Time to persist datastore: 20 ms

Answer 1

这是开发服务器的一个已知错误，由文件被锁定在文件系统中引起。请参阅this logged issue .

停止/重新启动开发服务器是一种解决方法。