tomcat源码解析（七）：server和service

server和service的作用是什么？

Catalina主要包括connector和container两个模块，connector负责接收请求，传递给container，而container负责处理请求。

service的作用是统一管理connector和container，一个service可以包括多个connector和一个container。而server的作用是，管理所有的service，一个server可以包括多个service。server负责管理所有service的生命周期，这样就管理了所有的connector和container，以及connector和container的所有内部组件。这样就不需要单独对connector和container单独进行开启或关闭了。

主要流程

初始化server

/** * Invoke a pre-startup initialization. This is used to allow connectors * to bind to restricted ports under Unix operating environments. */public void initialize()throws LifecycleException {    if (initialized)        throw new LifecycleException (            sm.getString("standardServer.initialize.initialized"));    initialized = true;    // Initialize our defined Services    for (int i = 0; i < services.length; i++) {        services[i].initialize();    }}

初始化service

/** * Invoke a pre-startup initialization. This is used to allow connectors * to bind to restricted ports under Unix operating environments. */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();            }    }}

启动server,调用service.start()

/** * Prepare for the beginning of active use of the public methods of this * component.  This method should be called before any of the public * methods of this component are utilized.  It should also send a * LifecycleEvent of type START_EVENT to any registered listeners. * * @exception LifecycleException if this component detects a fatal error *  that prevents this component from being used */public void start() throws LifecycleException {    // Validate and update our current component state    if (started)        throw new LifecycleException            (sm.getString("standardServer.start.started"));    // Notify our interested LifecycleListeners    lifecycle.fireLifecycleEvent(BEFORE_START_EVENT, null);    lifecycle.fireLifecycleEvent(START_EVENT, null);    started = true;    // Start our defined Services    synchronized (services) {        for (int i = 0; i < services.length; i++) {            if (services[i] instanceof Lifecycle)                ((Lifecycle) services[i]).start();        }    }    // Notify our interested LifecycleListeners    lifecycle.fireLifecycleEvent(AFTER_START_EVENT, null);}

启动service，会调用connector和container的start()，这样connector和container都启动啦。

/** * Prepare for the beginning of active use of the public methods of this * component.  This method should be called before any of the public * methods of this component are utilized.  It should also send a * LifecycleEvent of type START_EVENT to any registered listeners. * * @exception LifecycleException if this component detects a fatal error *  that prevents this component from being used */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);}

server.await()，监听8005端口消息，若收到shutdown命令，就关闭serversocket，并返回。Bootstrap.main()中，从StandardServer.await()返回后，会执行StandardServer.stop()，就可以关闭所有service了。

/** * Wait until a proper shutdown command is received, then return. */public void await() {    // Set up a server socket to wait on    // 监听8005端口    ServerSocket serverSocket = null;    try {        serverSocket =            new ServerSocket(port, 1,                             InetAddress.getByName("127.0.0.1"));    } catch (IOException e) {        System.err.println("StandardServer.await: create[" + port                           + "]: " + e);        e.printStackTrace();        System.exit(1);    }    // Loop waiting for a connection and a valid command    while (true) {        // Wait for the next connection        Socket socket = null;        InputStream stream = null;        try {            socket = serverSocket.accept();            socket.setSoTimeout(10 * 1000);  // Ten seconds            stream = socket.getInputStream();        } catch (AccessControlException ace) {            System.err.println("StandardServer.accept security exception: "                               + ace.getMessage());            continue;        } catch (IOException e) {            System.err.println("StandardServer.await: accept: " + e);            e.printStackTrace();            System.exit(1);        }        // Read a set of characters from the socket        StringBuffer command = new StringBuffer();        int expected = 1024; // Cut off to avoid DoS attack        while (expected < shutdown.length()) {            if (random == null)                random = new Random(System.currentTimeMillis());            expected += (random.nextInt() % 1024);        }        while (expected > 0) {            int ch = -1;            try {                ch = stream.read();            } catch (IOException e) {                System.err.println("StandardServer.await: read: " + e);                e.printStackTrace();                ch = -1;            }            if (ch < 32)  // Control character or EOF terminates loop                break;            command.append((char) ch);            expected--;        }        // Close the socket now that we are done with it        try {            socket.close();        } catch (IOException e) {            ;        }        // Match against our command string        System.out.println("[StandardServer] command: " + command);        boolean match = command.toString().equals(shutdown);        if (match) {            break;        } else            System.err.println("StandardServer.await: Invalid command '" +                               command.toString() + "' received");    }    // Close the server socket and return    try {        serverSocket.close();    } catch (IOException e) {        ;    }}

一个service可以包括多个connector和一个container，一个connector收到请求后将它发给container处理，service怎么样将connector和container关联起来呢？

在service.setContainer()中，会关联二者。

/** * Set the <code>Container</code> that handles requests for all * <code>Connectors</code> associated with this Service. * * @param container The new Container */public void setContainer(Container container) {    Container oldContainer = this.container;    if ((oldContainer != null) && (oldContainer 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);}

从await()返回后，调用server.stop()。

// Start the new serverif (server instanceof Lifecycle) {  try {    server.initialize();    ((Lifecycle) server).start();    server.await();    // the program waits until the await method returns,    // i.e. until a shutdown command is received.  }  catch (LifecycleException e) {    e.printStackTrace(System.out);  }}// Shut down the serverif (server instanceof Lifecycle) {  try {    ((Lifecycle) server).stop();  }  catch (LifecycleException e) {    e.printStackTrace(System.out);  }}

socket

socket一直不是太明白，等我弄明白了再来补充。