How Tomcat work 之第十四章之service



Service

org.apache.catalina.Service 这个接口表示一个Service。一个Service可以拥有一个容器和多个连接器。你可以添加尽可能多的连接器，这些连接器与这个容器是相关的。清单14.6是Service的接口。

package org.apache.catalina;public interface Service {         public Container getContainer();         public void setContainer(Container container);         public String getInfo();         public String getName();         public void setName(String name);         public Server getServer();         public void setServer(Server server);         public void addConnector(Connector connector);         public Connector[] findConnectors();         public void removeConnector(Connector connector);         public void initialize() throws LifecycleException;} 

StandardService

org.apache.catalina.core.StandardService类是Service的标准实现。这个类的initialize方法初始化了添加到这个Service的所有的连接器。这个类同时也实现了org.apache.catalian.Lifecycle接口。它的start方法开启了容器和所有的连接器。

Container和Connector(s)

一个StandardService实例包含了两类组件：一个容器和一个或者多个连接器。拥有更多的的连接器使得Tomcat能够支持更多的协议。一个连接器可以服务HTTP请求则另一个连接器可以支持HTTPS请求。

StandardService类使用container变量，一个对象的引用作为Container的实例，以conncetors数组代表所有的连接器。

private Container container = null;private Connector connectors[] = new Connector[0];

使用setContainer方法使一个container与一个Service关联。代码清单如下：

public void setContainer(Container container) {Container oldContainer = this.container;

if ((oldContainer != null) && (oldContainer instanceof Engine))

instanceof Engine)) ((Engine) oldContainer).setService(null);

this.container = container;

if ((this.container != null) && (this.container instanceof Engine))

  ((Engine) this.container).setService(this);

if (started && (this.container != null) 

    &&(this.container instanceof Lifecycle)) {

try {

((Lifecycle) this.container).start();

}catch (LifecycleException e) {

;

}

}

synchronized (connectors) {

for (int i = 0; i < connectors.length; i++)

connectors[i].setContainer(this.container);

}

if (started && (oldContainer != null) &&

    (oldContainer instanceof Lifecycle)) {    try {

((Lifecycle) oldContainer).stop();

}

catch (LifecycleException e) {

;

}

}

// Report this property change to interested listeners

support.firePropertyChange("container", oldContainer,

this.container);}

与这个Service相关联的container通过setContainer方法传递，那么这个Service相关联的每个connector对象在container与每个connector之间建立了一种关联。

为了给Service对象添加一个连接器，使用addConnector方法。为了移除一个连接器，调用removeConnector方法。addConnector和removeCon方法的代码清单如下：

public void addConnector(Connector connector) {

  synchronized (connectors) {

connector.setContainer(this.container);

connector.setService(this);

Connector results[] = new Connector[connectors.length + 1];

System.arraycopy(connectors, 0, results, 0, connectors.length);

results[connectors.length] = connector;

connectors = results;

if (initialized) {

    try {

connector.initialize();

}

    catch (LifecycleException e) {

e.printStackTrace(System.err);

}

}

if (started && (connector instanceof Lifecycle)) {

     try{

((Lifecycle) connector).start();

}

catch (LifecycleException e) {

;

}

}

// Report this property change to interested listeners

support.firePropertyChange("connector", null, connector);

  }

}

public void removeConnector(Connector connector) {

   synchronized (connectors) {

int j = -1;

for (int i = 0; i < connectors.length; i++) {

if (connector == connectors [i]) {

j = i;

break;

}

}

if (j < 0)

return;

if (started && (connectors[j] instanceof Lifecycle)) {

try {

((Lifecycle) connectors[j]).stop();

}

catch (LifecycleException e) {

;

}

}

connectors[j].setContainer(null);

connector.setService(null);

int k = 0;

Connector results[] = new Connector[connectors.length - 1];

for (int i = 0; i < connectors.length; i++) {

if (i != j)

results[k++] = connectors[i];

}

connectors = results;

// Report this property change to interested listeners

support.firePropertyChange("connector", connector, null);

    }

}

addConnector方法初始化和开启添加的连接器。

Lifecycle方法

生命周期方法是从Lifecycle接口中继承的start方法和stop方法，外加initialize方法。initialize方法调用了与这个Service相关的所有connector的initialize方法。这个方法的代码清单如下：

public void initialize() throws LifecycleException {     if (initialized)          throw new LifecycleException (sm.getString("StandardService.initialize.initialized"));

initialized = true;

// Initialize our defined Connectors

synchronized (connectors) {

for (int i = 0; i < connectors.length; i++) {

connectors[i].initialize();

}

}}

start方法启动了关联的container和添加到这个Service的connector。代码清单如下：

public void start() throws LifecycleException {        // Validate and update our current component state

if (started) {

throw new LifecycleException

(sm.getString("standardService.start.started"));

}

// Notify our interested LifecycleListeners

lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);

System.out.println

(sm.getString("standardService.start.name", this.name));

lifecycle.fireLifecycleEvent(START_EVENT, null);

started = true;

// Start our defined Container first

if (container != null) {

synchronized (container) {

if (container instanceof Lifecycle) {

((Lifecycle) container).start();

}

}

}

// Start our defined Connectors second

synchronized (connectors) {

for (int i = 0; i < connectors.length; i++) {

if (connectors[i] instanceof Lifecycle)

((Lifecycle) connectors[i]).start();

}

}

// Notify our interested LifecycleListeners

lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);}

stop方法停止了相关联的container和所有的连接器。其代码清单如下：

public void stop() throws LifecycleException {// Validate and update our current component state

if (!started) {

throw new LifecycleException

(sm.getString("standardService.stop.notStarted"));

}

// Notify our interested LifecycleListeners

lifecycle.fireLifecycleEvent(BEFORE_STOP_EVENT, null);

lifecycle.fireLifecycleEvent(STOP_EVENT, null);

System.out.println

(sm.getString("standardService.stop.name", this.name));

started = false;

// Stop our defined Connectors first

synchronized (connectors) {

for (int i = 0; i < connectors.length; i++) {

if (connectors[i] instanceof Lifecycle)

((Lifecycle) connectors[i]).stop();

}

}

// Stop our defined Container second

if (container != null) {

synchronized (container) {

if (container instanceof Lifecycle) {

((Lifecycle) container).stop();

}

}

}

// Notify our interested LifecycleListeners

lifecycle.fireLifecycleEvent(AFTER_STOP_EVENT, null);}