Chain Of Responsibility پترن در جاوا

public abstract class AbstractLogger {
     public static int INFO = 1;
     public static int DEBUG = 2;
     public static int ERROR = 3;

     protected int level;

     // next element in chain or responsibility
     protected AbstractLogger nextLogger;

     public void setNextLogger(AbstractLogger nextLogger) {
          this.nextLogger = nextLogger;
     }

     public void logMessage(int level, String message) {
          if (this.level <= level) {
              write(message);
          }
          if (nextLogger != null) {
              nextLogger.logMessage(level, message);
          }
     }

     abstract protected void write(String message);

}

public class ConsoleLogger extends AbstractLogger {

     public ConsoleLogger(int level) {
          this.level = level;
     }

     @Override
     protected void write(String message) {
          System.out.println("Standard Console::Logger: " + message);
     }
}


public class ErrorLogger extends AbstractLogger {

     public ErrorLogger(int level) {
          this.level = level;
     }

     @Override
     protected void write(String message) {
          System.out.println("Error Console::Logger: " + message);
     }
}

public class FileLogger extends AbstractLogger {

     public FileLogger(int level) {
          this.level = level;
     }

     @Override
     protected void write(String message) {
          System.out.println("File::Logger: " + message);
     }
}

public class ChainPatternDemo {

     private static AbstractLogger getChainOfLoggers() {

          AbstractLogger errorLogger = new ErrorLogger(AbstractLogger.ERROR);
          AbstractLogger fileLogger = new FileLogger(AbstractLogger.DEBUG);
          AbstractLogger consoleLogger = new ConsoleLogger(AbstractLogger.INFO);

          errorLogger.setNextLogger(fileLogger);
          fileLogger.setNextLogger(consoleLogger);

          return errorLogger;
     }

     public static void main(String[] args) {
          AbstractLogger loggerChain = getChainOfLoggers();

          loggerChain.logMessage(AbstractLogger.INFO, "This is an information.");

          loggerChain.logMessage(AbstractLogger.DEBUG,
                   "This is an debug level information.");

          loggerChain.logMessage(AbstractLogger.ERROR,
                   "This is an error information.");
     }
}