java - iswritable method in blob in appengine using java

Question

The blob is checked with a is writable method.

The code used is :

FileService fileService = FileServiceFactory.getFileService();
AppEngineFile file = fileService.getBlobFile(str);
Boolean writea=file.isWritable();

The value of writea displays true. So it refers that the blob is not finalized and can be used again (if I'm right).

Now my question is how to retrieve the blob and use it?

Answer 1

Blob 在可写时无法读取。在最终确定它们之前，它们是只写的，之后它们是只读的。