Define your own security manager : SecurityManager « Security « Java Tutorial

1. Java Tutorial
2. Security
3. SecurityManager

class CustomSecurityManager extends SecurityManager {
  public CustomSecurityManager() {
    super();
  }

  public void checkRead(String fileName) {
    if (fileName != null && fileName.endsWith(".java")) {
      throw new SecurityException(" You are not allowed to read " + " file names ending with .java");
    }
    super.checkRead(fileName);
  }

  public void checkWrite(String fileName) {
    if (fileName != null && fileName.endsWith(".java")) {
      throw new SecurityException(" You are not allowed to write "
          + " file names ending with .java");
    }
    super.checkWrite(fileName);
  }

  public void checkDelete(String fileName) {
    if (fileName != null && fileName.endsWith(".java")) {
      throw new SecurityException(" You are not allowed to delete "
          + " file names ending with .java");
    }
    super.checkDelete(fileName);
  }
}

public class MainClass {
  public static void main() {
    System.setSecurityManager(new CustomSecurityManager());
    SecurityManager secMgr = System.getSecurityManager();
    if (secMgr != null) {
      secMgr.checkRead("fileName");
    }
  }
}