Google Docs Java API中ListEntry.update()上的com.google.gdata.util.PreconditionFailedException

Question

我有一个应用程序来操纵谷歌电子表格的行.偶尔,当我调用ListEntry.update()时,我会收到以下堆栈跟踪:

Exception in thread "main" java.lang.reflect.InvocationTargetException
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 org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
Caused by: com.google.gdata.util.PreconditionFailedException: Precondition Failed
Mismatch: etags = ["E10QemAgYit7ImA-CEFaShYM"], version = [2ag9hk74om621l]
at com.google.gdata.client.http.HttpGDataRequest.handleErrorResponse(HttpGDataRequest.java:614)
at com.google.gdata.client.http.GoogleGDataRequest.handleErrorResponse(GoogleGDataRequest.java:564)
at com.google.gdata.client.http.HttpGDataRequest.checkResponse(HttpGDataRequest.java:560)
at com.google.gdata.client.http.HttpGDataRequest.execute(HttpGDataRequest.java:538)
at com.google.gdata.client.http.GoogleGDataRequest.execute(GoogleGDataRequest.java:536)
at com.google.gdata.client.Service.update(Service.java:1563)
at com.google.gdata.client.Service.update(Service.java:1530)
at com.google.gdata.client.GoogleService.update(GoogleService.java:597)
at com.google.gdata.data.BaseEntry.update(BaseEntry.java:639)
at feedProcessor.ProcessClientFeed.UpdateRow(ProcessClientFeed.java:466)
at feedProcessor.ProcessClientFeed.updateGoogleSpreadsheet(ProcessClientFeed.java:404)
at feedProcessor.ProcessClientFeed.processFeed(ProcessClientFeed.java:318)
at feedProcessor.ProcessClientFeed.main(ProcessClientFeed.java:61)
... 5 more

Answer 1

这是相关文档：

https://developers.google.com/gdata/javadoc/com/google/gdata/data/spreadsheet/ListEntry

https://developers.google.com/gdata/javadoc/com/google/gdata/data/BaseEntry#update()

根据这些文档， update() 函数甚至无法抛出 PreconditionFailedException，因此这些文档在这里基本上没有用。测试该问题表明，当您尝试在会话中多次调用同一行上的 update() 函数时，会引发此异常。确切地定义“会话”的内容仍不清楚，但如果您多次循环遍历所有行，并在每次迭代中对每一行调用 update() ，您将收到此错误。我所知道的唯一解决方案是编写软件，使每一行（ListEntry）只调用一次 update() 。