SecurityManager 堆栈溢出错误

Question

运行以下代码，我在 getPackage() 行收到 StackOverflowError。 如果我无法访问 getPackage() 来检查包，如何向我想要的包内的类授予权限？

package myPkg.security;

import java.security.Permission;

import javax.swing.JOptionPane;

public class SimpleSecurityManager extends SecurityManager {

    @Override
    public void checkPermission(Permission perm) {
 Class<?>[] contextArray = getClassContext();
 for (Class<?> c : contextArray) {
     checkPermission(perm, c);
 }
    }

    @Override
    public void checkPermission(Permission perm, Object context) {
 if (context instanceof Class) {
     Class clazz = (Class) context;
     Package pkg = clazz.getPackage(); // StackOverflowError
     String name = pkg.getName();
     if (name.startsWith("java.")) {
  // permission granted
  return;
     }
     if (name.startsWith("sun.")) {
  // permission granted
  return;
     }
     if (name.startsWith("myPkg.")) {
  // permission granted
  return;
     }
 }
 // permission denied
 throw new SecurityException("Permission denied for " + context);
    }

    public static void main(String[] args) {
 System.setSecurityManager(new SimpleSecurityManager());
 JOptionPane.showMessageDialog(null, "test");
    }

}

Answer 1

解决了！只需添加到第一个 checkPermission 方法的开头：

if (perm instanceof FilePermission) {
    if (perm.getActions().equals("read")) {
    // grant permission
    return;
    }
}

Answer 2

如果您只想限制包，那么如何实现checkPackageAccess 和/或 checkPackageDefinition 而不是通用的 checkPermission？