java.security.AccessControlException：使用 Java Web Start 访问被拒绝

发布于 2024-08-22 00:14:17 字数 520 浏览 10 评论 0原文

我在使用 JWS (Java Web Start) 访问文件时遇到一些问题。该程序添加了新的标签和图像。该程序在我的本地计算机上运行良好，但当我使用 JWS 在远程服务器上运行该程序时，会出现错误页面。以下是错误示例：

Exception in thread "AWT-EventQueue-0" java.security.AccessControlException: access denied (java.io.FilePermission add2.png read)
 at java.security.AccessControlContext.checkPermission(Unknown Source)
 at java.security.AccessController.checkPermission(Unknown Source)
 at java.lang.SecurityManager.checkPermission(Unknown Source)

即使在确保图像具有读取访问权限后也会发生这种情况。

有想法吗？

原文

I am having some issues with accessing files using JWS (Java Web Start). The program adds a new label and image. The program runs fine on my local computer but gives me pages of errors when I run the program on my remote server using JWS. Here's a sample of the error:

Exception in thread "AWT-EventQueue-0" java.security.AccessControlException: access denied (java.io.FilePermission add2.png read)
 at java.security.AccessControlContext.checkPermission(Unknown Source)
 at java.security.AccessController.checkPermission(Unknown Source)
 at java.lang.SecurityManager.checkPermission(Unknown Source)

This occurs even after making sure the images have read access.

Ideas?

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硬不硬你别怂 2024-08-29 00:14:17

与小程序一样，JNLP（Webstart）在客户端计算机上运行，而不是在服务器计算机上运行。客户端从网页下载程序并在本地计算机上运行。 java.io 中的任何引用都将指向本地磁盘文件系统（代码运行的地方），而不是远程磁盘文件系统（代码下载的地方），正如您所看到的那样预计。

您有 2 个选择：

将映像打包到 JAR 中并使用 ClassLoader#getResourceAsStream() 来从中获取 InputStream。

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
BufferedImage image = ImageIO.read(classLoader.getResourceAsStream("add2.png"));

将图像放在网络服务器中的公共位置，以便您可以通过 URL 访问它（仅比类路径中慢一点）。
```
BufferedImage image = ImageIO.read(new URL("http://example.com/add2.png"));
```

也就是说，无论如何，在 java.io 中使用相对路径而不是绝对路径都是一个坏主意。永远不要这样做。它将依赖于当前的工作目录，您无法控制该目录。

Like applets, JNLP (webstart) runs at client machine, not at server machine. The client downloads the program from a webpage and runs it at local machine. Any references in java.io stuff will point to the local disk file system (there where the code runs), not the remote disk file system (there where the code is been downloaded from) as you seem to expect.

You have 2 options:

Pack the image in the JAR and use ClassLoader#getResourceAsStream() instead to obtain an InputStream from it.

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
BufferedImage image = ImageIO.read(classLoader.getResourceAsStream("add2.png"));

Put the image in public location in the webserver, so that you can access it by URL (is only a tad slower than having in classpath).
```
BufferedImage image = ImageIO.read(new URL("http://example.com/add2.png"));
```

That said, regardless of all, using relative paths instead of absolute paths in java.io stuff is a bad idea. Never do this. It will be dependent on the current working directory, which you have no control over.

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