使用java以编程方式将图像上传到Google App引擎blobstore

我已经在谷歌应用引擎页面上看过“将文件写入Blobstore（实验性）”。

这就是我所拥有的：

// Get a file service FileService fileService = FileServiceFactory.getFileService(); // Create a new Blob file with mime-type "text/plain" AppEngineFile file = fileService.createNewBlobFile("text/plain"); // Open a channel to write to it boolean lock = false; FileWriteChannel writeChannel = fileService.openWriteChannel(file, lock); // Different standard Java ways of writing to the channel // are possible. Here we use a PrintWriter: **PrintWriter** out = new PrintWriter(Channels.newWriter(writeChannel, "UTF8")); out.println("The woods are lovely dark and deep."); out.println("But I have promises to keep."); // Close without finalizing and save the file path for writing later out.close(); String path = file.getFullPath(); // Write more to the file in a separate request: file = new AppEngineFile(path); // This time lock because we intend to finalize lock = true; writeChannel = fileService.openWriteChannel(file, lock); // This time we write to the channel directly writeChannel.write(ByteBuffer.wrap ("And miles to go before I sleep.".getBytes())); // Now finalize writeChannel.closeFinally(); // Later, read from the file using the file API lock = false; // Let other people read at the same time FileReadChannel readChannel = fileService.openReadChannel(file, false); // Again, different standard Java ways of reading from the channel. BufferedReader reader = new BufferedReader(Channels.newReader(readChannel, "UTF8")); String line = reader.readLine(); // line = "The woods are lovely dark and deep." readChannel.close(); // Now read from the file using the Blobstore API BlobKey blobKey = fileService.getBlobKey(file); BlobstoreService blobStoreService = BlobstoreServiceFactory.getBlobstoreService(); String segment = new String(blobStoreService.fetchData(blobKey, 30, 40)); 

不幸的是，这仅适用于文本文件。 我认为应该将PrintWriter更改为ImageWriter但在谷歌应用引擎中，不支持ImageWriter 。 我该怎么办？

Answer 1

您可以简单地将二进制数据写入blobstore：

 byte[] yourBinaryData = // get your data from request writeChannel.write(ByteBuffer.wrap(yourBinaryData)); 

Answer 2

你应该做这个：

 public static BlobKey toBlobstore(Blob imageData) throws FileNotFoundException, FinalizationException, LockException, IOException { if (null == imageData) return null; // Get a file service FileService fileService = FileServiceFactory.getFileService(); // Create a new Blob file with mime-type "image/png" AppEngineFile file = fileService.createNewBlobFile("image/jpeg");// png // Open a channel to write to it boolean lock = true; FileWriteChannel writeChannel = fileService.openWriteChannel(file, lock); // This time we write to the channel directly writeChannel.write(ByteBuffer.wrap (imageData.getBytes())); // Now finalize writeChannel.closeFinally(); return fileService.getBlobKey(file); }