SecurityManager StackOverflowError

Question

运行以下代码，我在getPackage()行得到一个StackOverflowError。如果我不能访问getPackage()来检查包，我怎么能只将权限授予包中的类呢？

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！只需在第一个checkPermission方法的开头添加：

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

Answer 2

如果你只想限制包，用checkPackageAccess和/或checkPackageDefinition代替通用的checkPermission怎么样？