NoClassDefFoundError: java.io.FileOutputStream is a restricted class

Question

我正在 java 中开发 google 应用程序，但出现此错误：仅 java.io.FileOutputStream is a restricted class 当我尝试上传比其他文件更大的 csv 文件时。当我上传 5-6kb 之类的文件时一切正常，但 30kb 文件出现错误。我当然导入了所有库并阅读了一些 tutorial/questions 但我不知道如何解决这个问题。

servlet 上的代码：

FileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);
        upload.setFileSizeMax(50000);
        upload.setSizeMax(50000);
        List<FileItem> items = upload.parseRequest(req); // <-- error line (48)

java.lang.NoClassDefFoundError: java.io.FileOutputStream is a restricted class. Please see the Google  App Engine developer's guide for more details.
at com.google.appengine.tools.development.agent.runtime.Runtime.reject(Runtime.java:50)
at org.apache.commons.io.output.DeferredFileOutputStream.thresholdReached(DeferredFileOutputStream.java:178)
at org.apache.commons.io.output.ThresholdingOutputStream.checkThreshold(ThresholdingOutputStream.java:224)
at org.apache.commons.io.output.ThresholdingOutputStream.write(ThresholdingOutputStream.java:128)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:108)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:70)
at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:347)
at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115)
at it.injenia.gestionefirme.servlet.uploadkind.UploadKind.doPost(UploadKind.java:48)

Answer 1

A Google 不允许 App Engine 应用程序写入文件系统。

上传适用于较小的文件，因为它们保存在内存中。要在内存中存储更大的文件，您可以增加 10KB 的默认大小阈值。

文档：http://commons.apache.org/proper/commons-fileupload/apidocs/org/apache/commons/fileupload/disk/DiskFileItemFactory.html

NoClassDefFoundError: java.io.FileOutputStream is a restricted class

NoClassDefFoundError: java.io.FileOutputStream is a restricted class

java

google-app-engine

file-upload

apache-commons