moscalar.java

用snmp4j实现的agent,代码比较多,但是很值得一看,尤其是对于要用SNMP监控信息的编程者,可以仔细研究一下里面的代码.

      MOChangeEvent event =
          new MOChangeEvent(this, this, vb.getOid(), getValue(),
                            vb.getVariable(), false);
      fireBeforeMOChange(event);
    }
    request.setUndoValue(getValue());
    changeValue(vb.getVariable());
    status.setPhaseComplete(true);
    if (moChangeListeners != null) {
      MOChangeEvent event =
          new MOChangeEvent(this, this, request.getVariableBinding().getOid(),
                            (Variable)request.getUndoValue(),
                            vb.getVariable(), false);
      fireAfterMOChange(event);
    }
  }

  /**
   * Changes the value of this scalar on behalf of a commit or undo operation.
   * Overwrite this method for easy and simple instrumentation. By default
   * {@link #setValue(Variable value)} is called.
   * @param value
   *    the new value.
   * @return
   *    a SNMP error status if the operation failed (should be avoided).
   * @since 1.2
   */
  protected int changeValue(Variable value) {
    return setValue(value);
  }

  public void undo(SubRequest request) {
    RequestStatus status = request.getStatus();
    if ((request.getUndoValue() != null) &&
        (request.getUndoValue() instanceof Variable)) {
      int errorStatus = changeValue((Variable)request.getUndoValue());
      status.setErrorStatus(errorStatus);
      status.setPhaseComplete(true);
    }
    else {
      status.setErrorStatus(SnmpConstants.SNMP_ERROR_UNDO_FAILED);
    }
  }

  public void cleanup(SubRequest request) {
    request.setUndoValue(null);
    request.getStatus().setPhaseComplete(true);
  }

  /**
   * Gets the instance OID of this scalar managed object.
   * @return
   *    the instance OID (by reference).
   */
  public OID getOid() {
    return oid;
  }

  public OID getLowerBound() {
    if (lowerBound == null) {
      lowerBound = new OID(oid.getValue(), 0, oid.size()-1);
    }
    return lowerBound;
  }

  public OID getUpperBound() {
    if (upperBound == null) {
      upperBound = new OID(getLowerBound().nextPeer());
    }
    return upperBound;
  }

  public boolean isCovered(MOScope other) {
    return (other.getLowerBound().startsWith(oid) &&
            (other.getLowerBound().size() > oid.size() ||
             other.isLowerIncluded())) &&
            (other.getUpperBound().startsWith(oid) &&
             ((other.getUpperBound().size() > oid.size()) ||
              other.isUpperIncluded()));
  }

  public boolean isLowerIncluded() {
    return true;
  }

  public boolean isUpperIncluded() {
    return false;
  }

  /**
   * Returns the actual value of this scalar managed object. For a basic
   * instrumentation, overwrite this method to provide always the actual
   * value and/or to update the internal <code>value</code> member and
   * call <code>super.</code>{@link #getValue()}.
   *
   * @return
   *    a non <code>null</code> Variable with the same syntax defined for
   *    this scalar object.
   */
  public Variable getValue() {
    return value;
  }

  public boolean isVolatile() {
    return isVolatile;
  }

  /**
   * Sets the value of this scalar managed object without checking it for
   * the correct syntax.
   * @param value
   *    a Variable with the with the same syntax defined for
   *    this scalar object (not checked).
   * @return
   *    a SNMP error code (zero indicating success by default).
   */
  public int setValue(Variable value) {
    this.value = value;
    return SnmpConstants.SNMP_ERROR_SUCCESS;
  }

  /**
   * Sets the volatile flag for this instance.
   * @param isVolatile
   *    if <code>true</code> the state of this object will not be persistently
   *    stored, otherwise the agent may save the state of this object
   *    persistently.
   */
  public void setVolatile(boolean isVolatile) {
    this.isVolatile = isVolatile;
  }

  public boolean isOverlapping(MOScope other) {
    return DefaultMOScope.overlaps(this, other);
  }

  /**
   * Adds a value validation listener to check new values.
   * @param l
   *   a <code>MOValueValidationListener</code> instance.
   */
  public synchronized void addMOValueValidationListener(
      MOValueValidationListener l) {
      if (moValueValidationListeners == null) {
        moValueValidationListeners = new Vector(2);
      }
      moValueValidationListeners.add(l);
  }

  /**
   * Removes a value validation listener
   * @param l
   *    a <code>MOValueValidationListener</code> instance.
   */
  public synchronized void removeMOValueValidationListener(
      MOValueValidationListener l) {
      if (moValueValidationListeners != null) {
        moValueValidationListeners.remove(l);
      }
  }

  protected void fireValidate(MOValueValidationEvent validationEvent) {
    if (moValueValidationListeners != null) {
      Vector listeners = moValueValidationListeners;
      int count = listeners.size();
      for (int i = 0; i < count; i++) {
        ((MOValueValidationListener) listeners.elementAt(i)).validate(
            validationEvent);
      }
    }
  }

  public OID getID() {
    return getOid();
  }

  public synchronized void load(MOInput input) throws IOException {
    Variable v = input.readVariable();
    setValue(v);
  }

  public synchronized void save(MOOutput output) throws IOException {
    output.writeVariable(value);
  }

  public boolean covers(OID oid) {
    return oid.startsWith(this.oid);
  }

  public String toString() {
    return getClass().getName()+"[oid="+getOid()+",access="+access+
        ",value="+getValue()+
        ",volatile="+isVolatile()+toStringDetails()+"]";
  }

  protected String toStringDetails() {
    return "";
  }

  /**
   * Adds a <code>MOChangeListener</code> that needs to be informed about
   * state changes of this scalar.
   * @param l
   *    a <code>MOChangeListener</code> instance.
   * @since 1.1
   */
  public synchronized void addMOChangeListener(MOChangeListener l) {
    if (moChangeListeners == null) {
      moChangeListeners = new Vector(2);
    }
    moChangeListeners.add(l);
  }

  /**
   * Removes a <code>MOChangeListener</code>.
   * @param l
   *    a <code>MOChangeListener</code> instance.
   * @since 1.1
   */
  public synchronized void removeMOChangeListener(MOChangeListener l) {
    if (moChangeListeners != null) {
      moChangeListeners.remove(l);
    }
  }

  protected void fireBeforePrepareMOChange(MOChangeEvent changeEvent) {
    if (moChangeListeners != null) {
      Vector listeners = moChangeListeners;
      int count = listeners.size();
      for (int i = 0; i < count; i++) {
        ((MOChangeListener) listeners.get(i)).beforePrepareMOChange(
            changeEvent);
      }
    }
  }

  protected void fireAfterPrepareMOChange(MOChangeEvent changeEvent) {
    if (moChangeListeners != null) {
      Vector listeners = moChangeListeners;
      int count = listeners.size();
      for (int i = 0; i < count; i++) {
        ((MOChangeListener) listeners.get(i)).afterPrepareMOChange(changeEvent);
      }
    }
  }

  protected void fireBeforeMOChange(MOChangeEvent changeEvent) {
    if (moChangeListeners != null) {
      Vector listeners = moChangeListeners;
      int count = listeners.size();
      for (int i = 0; i < count; i++) {
        ((MOChangeListener) listeners.get(i)).beforeMOChange(changeEvent);
      }
    }
  }

  protected void fireAfterMOChange(MOChangeEvent changeEvent) {
    if (moChangeListeners != null) {
      Vector listeners = moChangeListeners;
      int count = listeners.size();
      for (int i = 0; i < count; i++) {
        ((MOChangeListener) listeners.get(i)).afterMOChange(changeEvent);
      }
    }
  }
}