Tomcat 系列篇六-介绍下 Lifecycle

public interface Lifecycle {


    
    public static final String BEFORE_INIT_EVENT = "before_init";

    public static final String AFTER_INIT_EVENT = "after_init";

    public static final String START_EVENT = "start";

    public static final String BEFORE_START_EVENT = "before_start";

    public static final String AFTER_START_EVENT = "after_start";

    public static final String STOP_EVENT = "stop";

    public static final String BEFORE_STOP_EVENT = "before_stop";

    public static final String AFTER_STOP_EVENT = "after_stop";

    public static final String AFTER_DESTROY_EVENT = "after_destroy";

    public static final String BEFORE_DESTROY_EVENT = "before_destroy";

    public static final String PERIODIC_EVENT = "periodic";

    public static final String CONFIGURE_START_EVENT = "configure_start";

    public static final String CONFIGURE_STOP_EVENT = "configure_stop";

    public void addLifecycleListener(LifecycleListener listener);

    public LifecycleListener[] findLifecycleListeners();

    public void removeLifecycleListener(LifecycleListener listener);

    public void init() throws LifecycleException;

    public void start() throws LifecycleException;

    public void stop() throws LifecycleException;

    public void destroy() throws LifecycleException;

    public LifecycleState getState();

    public String getStateName();


    /**
     * Marker interface used to indicate that the instance should only be used
     * once. Calling {@link #stop()} on an instance that supports this interface
     * will automatically call {@link #destroy()} after {@link #stop()}
     * completes.
     */
    public interface SingleUse {
    }
}

public enum LifecycleState {
    NEW(false, null),
    INITIALIZING(false, Lifecycle.BEFORE_INIT_EVENT),
    INITIALIZED(false, Lifecycle.AFTER_INIT_EVENT),
    STARTING_PREP(false, Lifecycle.BEFORE_START_EVENT),
    STARTING(true, Lifecycle.START_EVENT),
    STARTED(true, Lifecycle.AFTER_START_EVENT),
    STOPPING_PREP(true, Lifecycle.BEFORE_STOP_EVENT),
    STOPPING(false, Lifecycle.STOP_EVENT),
    STOPPED(false, Lifecycle.AFTER_STOP_EVENT),
    DESTROYING(false, Lifecycle.BEFORE_DESTROY_EVENT),
    DESTROYED(false, Lifecycle.AFTER_DESTROY_EVENT),
    FAILED(false, null);

    private final boolean available;
    private final String lifecycleEvent;

    private LifecycleState(boolean available, String lifecycleEvent) {
        this.available = available;
        this.lifecycleEvent = lifecycleEvent;
    }

    /**
     * May the public methods other than property getters/setters and lifecycle
     * methods be called for a component in this state? It returns
     * <code>true</code> for any component in any of the following states:
     * <ul>
     * <li>{@link #STARTING}</li>
     * <li>{@link #STARTED}</li>
     * <li>{@link #STOPPING_PREP}</li>
     * </ul>
     *
     * @return <code>true</code> if the component is available for use,
     *         otherwise <code>false</code>
     */
    public boolean isAvailable() {
        return available;
    }

    public String getLifecycleEvent() {
        return lifecycleEvent;
    }
}

@Override
public final synchronized void init() throws LifecycleException {
    if (!state.equals(LifecycleState.NEW)) {
    // 只有状态是 new 才可以执行初始化 init
        invalidTransition(Lifecycle.BEFORE_INIT_EVENT);
    }

    try {
        setStateInternal(LifecycleState.INITIALIZING, null, false);
        initInternal();
        setStateInternal(LifecycleState.INITIALIZED, null, false);
    } catch (Throwable t) {
        handleSubClassException(t, "lifecycleBase.initFail", toString());
    }
}

private synchronized void setStateInternal(LifecycleState state, Object data, boolean check)
            throws LifecycleException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("lifecycleBase.setState", this, state));
        }

        if (check) {
            // Must have been triggered by one of the abstract methods (assume
            // code in this class is correct)
            // null is never a valid state
            if (state == null) {
                invalidTransition("null");
                // Unreachable code - here to stop eclipse complaining about
                // a possible NPE further down the method
                return;
            }

            // Any method can transition to failed
            // startInternal() permits STARTING_PREP to STARTING
            // stopInternal() permits STOPPING_PREP to STOPPING and FAILED to
            // STOPPING
            if (!(state == LifecycleState.FAILED ||
                    (this.state == LifecycleState.STARTING_PREP &&
                            state == LifecycleState.STARTING) ||
                    (this.state == LifecycleState.STOPPING_PREP &&
                            state == LifecycleState.STOPPING) ||
                    (this.state == LifecycleState.FAILED &&
                            state == LifecycleState.STOPPING))) {
                // No other transition permitted
                invalidTransition(state.name());
            }
        }

        this.state = state;
        String lifecycleEvent = state.getLifecycleEvent();
        if (lifecycleEvent != null) {
            fireLifecycleEvent(lifecycleEvent, data);
        }
    }

protected void fireLifecycleEvent(String type, Object data) {
    LifecycleEvent event = new LifecycleEvent(this, type, data);
    for (LifecycleListener listener : lifecycleListeners) {
        listener.lifecycleEvent(event);
    }
}

@Override
protected void initInternal() throws LifecycleException {

    super.initInternal();

    if (protocolHandler == null) {
        throw new LifecycleException(
                sm.getString("coyoteConnector.protocolHandlerInstantiationFailed"));
    }

    // Initialize adapter
    adapter = new CoyoteAdapter(this);
    protocolHandler.setAdapter(adapter);
    if (service != null) {
        protocolHandler.setUtilityExecutor(service.getServer().getUtilityExecutor());
    }

    // Make sure parseBodyMethodsSet has a default
    if (null == parseBodyMethodsSet) {
        setParseBodyMethods(getParseBodyMethods());
    }

    if (protocolHandler.isAprRequired() && !AprStatus.isInstanceCreated()) {
        throw new LifecycleException(sm.getString("coyoteConnector.protocolHandlerNoAprListener",
                getProtocolHandlerClassName()));
    }
    if (protocolHandler.isAprRequired() && !AprStatus.isAprAvailable()) {
        throw new LifecycleException(sm.getString("coyoteConnector.protocolHandlerNoAprLibrary",
                getProtocolHandlerClassName()));
    }
    if (AprStatus.isAprAvailable() && AprStatus.getUseOpenSSL() &&
            protocolHandler instanceof AbstractHttp11JsseProtocol) {
        AbstractHttp11JsseProtocol<?> jsseProtocolHandler =
                (AbstractHttp11JsseProtocol<?>) protocolHandler;
        if (jsseProtocolHandler.isSSLEnabled() &&
                jsseProtocolHandler.getSslImplementationName() == null) {
            // OpenSSL is compatible with the JSSE configuration, so use it if APR is available
            jsseProtocolHandler.setSslImplementationName(OpenSSLImplementation.class.getName());
        }
    }

    try {
        protocolHandler.init();
    } catch (Exception e) {
        throw new LifecycleException(
                sm.getString("coyoteConnector.protocolHandlerInitializationFailed"), e);
    }
}

@Override
public final synchronized void start() throws LifecycleException {

    if (LifecycleState.STARTING_PREP.equals(state) || LifecycleState.STARTING.equals(state) ||
            LifecycleState.STARTED.equals(state)) {

        if (log.isDebugEnabled()) {
            Exception e = new LifecycleException();
            log.debug(sm.getString("lifecycleBase.alreadyStarted", toString()), e);
        } else if (log.isInfoEnabled()) {
            log.info(sm.getString("lifecycleBase.alreadyStarted", toString()));
        }

        return;
    }

    if (state.equals(LifecycleState.NEW)) {
        init();
    } else if (state.equals(LifecycleState.FAILED)) {
        stop();
    } else if (!state.equals(LifecycleState.INITIALIZED) &&
            !state.equals(LifecycleState.STOPPED)) {
        invalidTransition(Lifecycle.BEFORE_START_EVENT);
    }

    try {
        setStateInternal(LifecycleState.STARTING_PREP, null, false);
        startInternal();
        if (state.equals(LifecycleState.FAILED)) {
            // This is a 'controlled' failure. The component put itself into the
            // FAILED state so call stop() to complete the clean-up.
            stop();
        } else if (!state.equals(LifecycleState.STARTING)) {
            // Shouldn't be necessary but acts as a check that sub-classes are
            // doing what they are supposed to.
            invalidTransition(Lifecycle.AFTER_START_EVENT);
        } else {
            setStateInternal(LifecycleState.STARTED, null, false);
        }
    } catch (Throwable t) {
        // This is an 'uncontrolled' failure so put the component into the
        // FAILED state and throw an exception.
        handleSubClassException(t, "lifecycleBase.startFail", toString());
    }
}