GWT文件上傳java.security.AccessControlException：訪問被拒絕（java.io.FilePermission中

Question

我有一個文件上傳Servlet和嘗試一些文件存儲爲：

try{ 
    File uploadedFile = new File(UPLOAD_DIRECTORY + fileName); 
    File uploadedFile = new File("/"+fileName); 
    item.write(uploadedFile); 
} 
catch (Exception e) { 
    e.printStackTrace(); 
} 

之後，我得到以下錯誤：

java.security.AccessControlException: access denied (java.io.FilePermission /untitled.html write) 
    at java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) 
    at java.security.AccessController.checkPermission(AccessController.java:546) 
    at java.lang.SecurityManager.checkPermission(SecurityManager.java:532) 

我該如何解決呢？

Answer 1

你既可以使/可寫你的應用服務器（這似乎並不像一個偉大的想法對我來說）或存儲上傳編輯文件在另一個可寫的位置。

File uploadedFile = new File(UPLOAD_DIRECTORY + fileName); 
File uploadedFile = new File("/"+fileName); 

您似乎也試圖聲明uploadedFile兩次。從錯誤，它看起來像UPLOAD_DIRECTORY是/或您實際上使用第二行。也許你只需要在UPLOAD_DIRECTORY提供正確的位置？

要回答關於Java策略文件的註釋的問題：

從Security and Permissions java.sun.com上：

There is one policy file for Java platform installation (system) and an optional policy file for each user. The system policy file is in {java.home}/lib/security/java.policy, and the user policy file is in each user's home directory. The system and user policy files are combined. So for example,there could be a system policy file with very few permissions granted to all users on the system, and individual policy files granting additional permissions to certain users.

見在政策文件中設置文件系統權限的File Permission部分。

爲了重申我自己的意見，您還需要注意操作系統中的文件系統權限，其中的控制取決於您使用的操作系統。