Server服务器 Server接口表示整个Catalina Servlet容器以及其它组件。 它提供了一种优雅的机制来启动和停止整个系统。不必再单独的启动连接器和容器了。 当服务器启动的时候，它启动它内部的所有组件。然后无限期的等待关闭命令， 如果你想要关闭系统，发送一个关闭命令道指定端口即可。当服务器收到正确的关闭指令后，它停止所有组件的服务。 服务器还使用了另外一个组件，服务(service)，它用来持有组件
public interface Server {
// ------------------------------------------------------------- Properties
/**
* Return descriptive information about this Server implementation and
* the corresponding version number, in the format
* <code><description>/<version></code>.
*/
public String getInfo();
/**
* Return the global naming resources.
*/
public NamingResources getGlobalNamingResources();
/**
* Set the global naming resources.
*
* @param namingResources The new global naming resources
*/
public void setGlobalNamingResources
(NamingResources globalNamingResources);
/**
* Return the port number we listen to for shutdown commands.
*/
public int getPort();
/**
* Set the port number we listen to for shutdown commands.
*
* @param port The new port number
*/
public void setPort(int port);
/**
* Return the shutdown command string we are waiting for.
*/
public String getShutdown();
/**
* Set the shutdown command we are waiting for.
*
* @param shutdown The new shutdown command
*/
public void setShutdown(String shutdown);
// --------------------------------------------------------- Public Methods
/**
* Add a new Service to the set of defined Services.
*
* @param service The Service to be added
*/
public void addService(Service service);
/**
* Wait until a proper shutdown command is received, then return.
*/
public void await();
/**
* Return the specified Service (if it exists); otherwise return
* <code>null</code>.
*
* @param name Name of the Service to be returned
*/
public Service findService(String name);
/**
* Return the set of Services defined within this Server.
*/
public Service[] findServices();
/**
* Remove the specified Service from the set associated from this
* Server.
*
* @param service The Service to be removed
*/
public void removeService(Service service);
/**
* Invoke a pre-startup initialization. This is used to allow connectors
* to bind to restricted ports under Unix operating environments.
*
* @exception LifecycleException If this server was already initialized.
*/
public void initialize()
throws LifecycleException;
}
属性shutdown用来持有一个停止服务的指令。属性port则是服务器等待关闭命令的端口。
可以调用服务器的addService方法将服务添加到服务器。使用removeService方法将服务删除。
findServices返回所有服务器中所有的服务。Initialize方法包括在启动之前需要执行的代码。
StandardServer类
StandardServer类是服务器的标准实现
一个服务器可以有零个或多个服务，StandardServer类提供了addService、removeService、findServices方法的实现。
另外还有四个跟生命周期相关的方法：initialize 、tart 、stop以及await。
initialize方法
Initialize方法用于初始化要添加到服务器实例上的服务
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();
}
}
注意该方法使用了一个名为initialized的变量来避免多次启动该服务器
start方法
可以使用start方法来启动一个服务器，StandardServer的start方法的实现将会启动所有服务及其相关组件，例如连接器和容器
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);
}
该方法使用了一个started布尔变量来避免一个服务器被启动两次。Stop方法会重置该变量的值
stop方法
public void stop() throws LifecycleException {
// Validate and update our current component state
if (!started)
throw new LifecycleException
(sm.getString("standardServer.stop.notStarted"));
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(BEFORE_STOP_EVENT, null);
lifecycle.fireLifecycleEvent(STOP_EVENT, null);
started = false;
// Stop our defined Services
for (int i = 0; i < services.length; i++) {
if (services[i] instanceof Lifecycle)
((Lifecycle) services[i]).stop();
}
// Notify our interested LifecycleListeners
lifecycle.fireLifecycleEvent(AFTER_STOP_EVENT, null);
}
await方法
Await负责整个Tomcat部署的停止机制
public void await() {
// Set up a server socket to wait on
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
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) {
;
}
}
方法await在8085端口创建一个ServerSocket对象，在while循环调用它的accept方法。
Accept方法仅仅接受8085端口的信息。它将接受到的信息跟shutdown命令进行匹配，
如果匹配的话跳出循环关闭SocketServer，如果不匹配继续while循环等待另一个命令。
服务
org.apache.catalina.Service接口用于表示服务。一个服务可以可以有一个容器和多个连接器。
可以添加多个连接器 ，并将它们跟容器相关联
public interface Service {
// ------------------------------------------------------------- Properties
/**
* Return the <code>Container</code> that handles requests for all
* <code>Connectors</code> associated with this Service.
*/
public Container getContainer();
/**
* 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);
/**
* Return descriptive information about this Service implementation and
* the corresponding version number, in the format
* <code><description>/<version></code>.
*/
public String getInfo();
/**
* Return the name of this Service.
*/
public String getName();
/**
* Set the name of this Service.
*
* @param name The new service name
*/
public void setName(String name);
/**
* Return the <code>Server</code> with which we are associated (if any).
*/
public Server getServer();
/**
* Set the <code>Server</code> with which we are associated (if any).
*
* @param server The server that owns this Service
*/
public void setServer(Server server);
// --------------------------------------------------------- Public Methods
/**
* Add a new Connector to the set of defined Connectors, and associate it
* with this Service's Container.
*
* @param connector The Connector to be added
*/
public void addConnector(Connector connector);
/**
* Find and return the set of Connectors associated with this Service.
*/
public Connector[] findConnectors();
/**
* Remove the specified Connector from the set associated from this
* Service. The removed Connector will also be disassociated from our
* Container.
*
* @param connector The Connector to be removed
*/
public void removeConnector(Connector connector);
/**
* Invoke a pre-startup initialization. This is used to allow connectors
* to bind to restricted ports under Unix operating environments.
*
* @exception LifecycleException If this server was already initialized.
*/
public void initialize()
throws LifecycleException;
}
StandardService类
StandardService类是Service接口的标准实现。StandardService类的initialize方法初始化所有的添加到该服务的连接器
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();
}
}
}
容器和连接器
一个StandardService实例包括两种组件：一个容器和多个连接器。
多个连接器可以使得Tomcat能服务于多个协议。一个协议用处处理HTTP请求，另一个用于处理HTTPS请求。
StandardService类用container变量来持有容器实例，用connectors数组来持有所有的连接器
private Container container = null;
private Connector connectors[] = new Connector[0];
要将一个容器跟一个服务相关联，可以使用它的setContainer方法
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);
}
要与服务相关联的容器传递给该每个连接器，这样来建立容器和每个连接器的关系。
要给一个服务添加连接器，可以使用addConnector方法。要删除一个连接器，可以使用removeConnector方法
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);
}
}
Start方法用于启动相关联的连接器和容器
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方法关闭所有关联连接器和容器
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);
}
例子
public final class Bootstrap {
public static void main(String[] args) {
System.setProperty("catalina.base", System.getProperty("user.dir"));
Connector connector = new HttpConnector();
Wrapper wrapper1 = new StandardWrapper();
wrapper1.setName("Primitive");
wrapper1.setServletClass("PrimitiveServlet");
Wrapper wrapper2 = new StandardWrapper();
wrapper2.setName("Modern");
wrapper2.setServletClass("ModernServlet");
Context context = new StandardContext();
// StandardContext's start method adds a default mapper
context.setPath("/app1");
context.setDocBase("app1");
context.addChild(wrapper1);
context.addChild(wrapper2);
LifecycleListener listener = new SimpleContextConfig();
((Lifecycle) context).addLifecycleListener(listener);
Host host = new StandardHost();
host.addChild(context);
host.setName("localhost");
host.setAppBase("webapps");
Loader loader = new WebappLoader();
context.setLoader(loader);
// context.addServletMapping(pattern, name);
context.addServletMapping("/Primitive", "Primitive");
context.addServletMapping("/Modern", "Modern");
Engine engine = new StandardEngine();
engine.addChild(host);
engine.setDefaultHost("localhost");
Service service = new StandardService();
service.setName("Stand-alone Service");
Server server = new StandardServer();
server.addService(service);
service.addConnector(connector);
service.setContainer(engine);
if (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);
}
}
if (server instanceof Lifecycle) {
try {
((Lifecycle) server).stop();
} catch (LifecycleException e) {
e.printStackTrace(System.out);
}
}
{
}
Bootstrap主方法创建了一个连接器、两个包装器、一个上下文、一个主机以及一个引擎。
然后将包装器添加到上下文，将上下文添加到主机，主机添加到引擎。它并没有将连接器和引擎相关联，
而是创建了一个一个服务对象，设置它的名字，创建一个服务器对象，并给该服务器添加服务。
然后，主方法将连接器和引擎添加到服务上。
这样讲连接器添加到服务上，连接器在服务上跟容器相关联。
然后主方法调用服务器的initialize和start方法。初始化连接器并启动它以及容器。
Stopper类
Stopper类提供了一种优雅的方式来关闭Catalina服务器。它还保证了所有生命周期组件的stop方法会被调用
public class Stopper {
public static void main(String[] args) {
// the following code is taken from the Stop method of
// the org.apache.catalina.startup.Catalina class
int port = 8005;
try {
Socket socket = new Socket("127.0.0.1", port);
OutputStream stream = socket.getOutputStream();
String shutdown = "SHUTDOWN";
for (int i = 0; i < shutdown.length(); i++)
stream.write(shutdown.charAt(i));
stream.flush();
stream.close();
socket.close();
System.out.println("The server was successfully shut down.");
} catch (IOException e) {
System.out.println("Error. The server has not been started.");
}
}
}