...
The compliant solution installs a custom security manager PasswordSecurityManager that overrides the checkExist method defined in SecurityManager class. An internal flag is used to keep track of whether the exit is permitted or not. The method setExitAllowed is used to set this flag to true. If the flag is false, a SecurityException is thrown. The System.exit call is not permitted to execute by catching the SecurityException in a try-catch block. After intercepting and performing mandatory clean-up operations, the setExitAllowed method is invoked. The program as a result exits gracefully.
| Code Block | ||
|---|---|---|
| ||
public class PasswordSecurityManager extends SecurityManager{
private boolean flag;
public PasswordSecurityManager(){
super();
flag = false;
}
public boolean isExitAllowed(){
if(flag == true)
return true;
else
return false;
}
public void checkExit(int status) {
if(!isExitAllowed())
throw new SecurityException();
}
public void setExitAllowed(boolean f) {
if(f == true)
flag = true;
else
flag = false;
}
}
public class InterceptExit {
public static void main(String[] args) {
PasswordSecurityManager secManager = new PasswordSecurityManager();
System.setSecurityManager(secManager);
try {
System.out.println("Regular code block");
System.exit(1); //abrupt exit call
}
catch (Throwable x) {
if (x instanceof SecurityException)
System.out.println("Intercepted System.exit()");
else
x.printStackTrace();
}
System.out.println("Executing code block...");
secManager.setExitAllowed(true); //permit exit
System.out.println("Finished block, exiting..."); //exit finally
}
}
|
...