从 Web 应用程序运行小程序时的 java.lang.RuntimePermission

问题描述：

我正在尝试从小程序中读取环境变量，这是我的代码

I'm trying to read a envrionment varaible from a applet, here is my code

    String env = System.getenv("TWS");
    System.out.println(env);
    Runtime rt = Runtime.getRuntime();
    String s = env + "\\WebStart.bat " ;
    System.out.println(s);
    try {
        Process p = rt.exec(s);
    } catch (Exception e) {
    }

当我通过右键单击并运行从 netbeans 运行代码时，它运行没有问题.

when i run the code from netbeans by right click and run, it is running without a problem.

但是当我将它放入 jar 文件时，将它添加到我的 Web 应用程序并尝试使用以下代码从 html 页面运行它

but when i put it to a jar file, add it to my web application and try to run it from a html page using the following code

<applet code="draw.class" archive='AppletTest.jar'>
   <param name="shape" value="triangle"/>
</applet>

我收到一个错误消息，说访问被拒绝，java.lang.RuntimePermission

i'm getting a error saying access denied , java.lang.RuntimePermission

我正在使用 tomcat 6 运行此 Web 应用程序.

i am running this web application using tomcat 6.

我已经阅读了一些指南，并在 tomcat 6 的 catalina.policy 文件中添加了以下条目并重新启动了 tomcat

i have read some guides and added the following entry to catalina.policy file in tomcat 6 and restarted tomcat

permission java.lang.RuntimePermission "accessDeclaredMembers";

但仍然是同样的警告.有人可以为这个问题提出一个解决方案吗?

but still the same warning. can some one please suggest a solution for this problem?

--兰加纳

答

当您从 netbeans 运行小程序时，Java 虚拟机在与您通过浏览器运行时不同的安全机制下运行它.

When you run your applet from netbeans, Java virtual machines runs it under a different security regime than when you run it through browser.

通过浏览器下载的小应用程序未使用安全证书签名，被视为不受信任的小应用程序，称为未签名小应用程序.在客户端上运行时，未签名的小程序在仅允许一组安全操作的安全沙箱中运行.您可以使用安全管理器.例如在你的情况下:

Applets, downloaded through browsers, that are not signed using a security certificate, are considered to be untrusted and referred to as unsigned applets. When running on a client, unsigned applets operate within a security sandbox that allows only a set of safe operations. You can check if a perticular permission is granted to you applet or not by using SecurityManager. For example in your case :

System.getSecurityManager().checkPermission(new RuntimePermission("accessDeclaredMembers"));

您可以在此处了解有关小程序安全性的更多信息> 和此处.可以找到有关制作签名小程序的非常好的教程此处.

You can know more about applet security here and here. A very nice tutorial on making signed applets can be found here.

从 Web 应用程序运行小程序时的 java.lang.RuntimePermission

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