深入剖析TOMCAT

TOMCAT

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容器分类

Engine:整个CatalinaServlet引擎

Host:包含一个或者多个Context容器的虚拟主机

Context:web应用容器，可以有多个wrapper

Wrapper:粒度最小的容器，没有子容器

相关组件：载入器，管道，映射器等

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请求响应流程

HttpConnector -->serverSocket.accept()-->HttpConnector.start--HttpConnector.run-->createProcessor()--> HttpProcessor.process(socket)-->解析填充req,res()-->connector.getContainer().invoke(request, response)-->容器.invoke-->(new SimplePipelineValveContext()).invokeNext--> valves[subscript].invoke-->basic.invoke-->HttpProcessor.process(socket).finishResponse;

 

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生命周期

Lifecyle接口

public void addLifecycleListener(LifecycleListener listener);
public LifecycleListener[] findLifecycleListeners();
public void removeLifecycleListener(LifecycleListener listener);
public void start() throws LifecycleException;
public void stop() throws LifecycleException;

LifecycleEvent

LifecycleListener

LifecycleSupport

容器实现Lifecyle接口 可以调用addLifecycleListener(LifecycleListener listener)增加监听器至LifecycleSupport.LifecycleListener[]，容器重写start，stop方法实现逻辑(对容器，子容器进行启动，关闭)，同时发送事件告知监听器，监听器实现具体逻辑。

((Lifecycle) context).addLifecycleListener(listener);
LifecycleSupport.fireLifecycleEvent(BEFORE_START_EVENT, null);
LifecycleListener.lifecycleEvent(LifecycleEvent event) {

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日志收集

Logger<--LoggerBase

public static final int FATAL = Integer.MIN_VALUE;
public static final int ERROR = 1;
public static final int WARNING = 2;
public static final int INFORMATION = 3;
public static final int DEBUG = 4;
public Container getContainer();
public void setContainer(Container container);
public String getInfo();
public int getVerbosity();
public void setVerbosity(int verbosity);
public void addPropertyChangeListener(PropertyChangeListener listener);
public void log(String message);
public void log(Exception exception, String msg);
public void log(String message, Throwable throwable);
public void log(String message, int verbosity);
public void log(String message, Throwable throwable, int verbosity);
public void removePropertyChangeListener(PropertyChangeListener listener);

FileLogger

SystemErrLogger

SystemOutLogger

载入器

loader

public ClassLoader getClassLoader();
public Container getContainer();
public void setContainer(Container container);
public DefaultContext getDefaultContext();
public void setDefaultContext(DefaultContext defaultContext);
public boolean getDelegate();
public void setDelegate(boolean delegate);
public String getInfo();
public boolean getReloadable();
public void setReloadable(boolean reloadable);
public void addPropertyChangeListener(PropertyChangeListener listener);
public void addRepository(String repository);
public String[] findRepositories();
public boolean modified();
public void removePropertyChangeListener(PropertyChangeListener listener);

Session管理

Request#getSession()-->this.doGetSession(true)：session.getSession()--> context.getManager()-->manager.createSession(sessionId):manager.findSession(this.requestedSessionId)

安全性

Realm领域对象

public Container getContainer();
public void setContainer(Container container);
public String getInfo();
public void addPropertyChangeListener(PropertyChangeListener listener);
public Principal authenticate(String username, String credentials);
public Principal authenticate(String username, byte[] credentials);
public Principal authenticate(String username, String digest,
                              String nonce, String nc, String cnonce,
                              String qop, String realm,
                              String md5a2);
public Principal authenticate(X509Certificate certs[]);
public boolean hasRole(Principal principal, String role);
public void removePropertyChangeListener(PropertyChangeListener listener);

class GenericPrincipal implements Principal

public GenericPrincipal(Realm realm, String name, String password) {
    this(realm, name, password, null);
}
public GenericPrincipal(Realm realm, String name, String password, List roles) {
    super();
    this.realm = realm;
    this.name = name;
    this.password = password;
    if (roles != null) {
        this.roles = new String[roles.size()];
        this.roles = (String[]) roles.toArray(this.roles);
        if (this.roles.length > 0)
            Arrays.sort(this.roles);
    }
}

LoginConfig

TOMCAT启动读取web.xml，如果包含Login-Config元素的配置，会创建loginconfig对象并设置对于属性加入验证阀

Authenticator

System.setProperty("catalina.base", System.getProperty("user.dir"));
Connector connector = new HttpConnector();
Wrapper wrapper1 = new SimpleWrapper();
wrapper1.setName("Primitive");
wrapper1.setServletClass("PrimitiveServlet");
Wrapper wrapper2 = new SimpleWrapper();
wrapper2.setName("Modern");
wrapper2.setServletClass("ModernServlet");

Context context = new StandardContext();
// StandardContext's start method adds a default mapper
context.setPath("/myApp");
context.setDocBase("myApp");
LifecycleListener listener = new SimpleContextConfig();
((Lifecycle) context).addLifecycleListener(listener);

context.addChild(wrapper1);
context.addChild(wrapper2);
// for simplicity, we don't add a valve, but you can add
// valves to context or wrapper just as you did in Chapter 6

Loader loader = new WebappLoader();
context.setLoader(loader);
// context.addServletMapping(pattern, name);
context.addServletMapping("/Primitive", "Primitive");
context.addServletMapping("/Modern", "Modern");
// add ContextConfig. This listener is important because it configures
// StandardContext (sets configured to true), otherwise StandardContext
// won't start

// add constraint
SecurityCollection securityCollection = new SecurityCollection();
securityCollection.addPattern("/");
securityCollection.addMethod("GET");

SecurityConstraint constraint = new SecurityConstraint();
constraint.addCollection(securityCollection);
constraint.addAuthRole("manager");
LoginConfig loginConfig = new LoginConfig();
loginConfig.setRealmName("Simple User Database Realm");
// add realm
Realm realm = new SimpleUserDatabaseRealm();
((SimpleUserDatabaseRealm) realm).createDatabase("conf/tomcat-users.xml");
context.setRealm(realm);
context.addConstraint(constraint);
context.setLoginConfig(loginConfig);

connector.setContainer(context);

try {
  connector.initialize();
  ((Lifecycle) connector).start();
  ((Lifecycle) context).start();

  // make the application wait until we press a key.
  System.in.read();
  ((Lifecycle) context).stop();
}
catch (Exception e) {
  e.printStackTrace();
}

StandardWrapper

singleThreadModel (STM)

servlet类可以继承STM接口，保证同一时间只有一个线程访问该servlet实例的service的方法，为了提高性能 servlet容器会创建多个servlet实例并发执行service,如service方法里面依赖外部资源，应该考虑可能引起同步问题

StandardWrapper

维护一个STM实例池 根据servlet完全限定名动态载入Servlet类，Servlet的service（）是由StandardWrapperValue调用

public Servlet allocate() throws ServletException {
...
servlet.init(ServletConfig servletConfig)
}

ServletConfig

public interface ServletConfig {
String getServletName();
ServletContext getServletContext();
String getInitParameter(String var1);
Enumeration<String> getInitParameterNames();
}

StandardWrapperFacade

包装类

StandardWrapperValue

StandardWrapper实例的基础阀:
1.执行与该servlet关联的所以过滤阀
2.执行servlet实例的service方法
为完成上述操作StandardWrapperValue.invoke还会执行下面操作
1.servlet = wrapper.allocate();
2.ApplicationFilterChain filterChain =createFilterChain(request, servlet);
3.调用过滤链的doFilte()方法，其中包括servlet实例的service方法
4.释放过滤链
6.若该service类不会被使用到，调用wrapper.unload( 5.wrapper.deallocate()
);

ApplicationFilterChain implements FilterChain

 public void doFilter(ServletRequest request, ServletResponse response)
    throws IOException, ServletException {}

ApplicationFilterConfig implements FilterConfig

 org.apache.catalina.core.StandardContext#start#filterStart#ApplicationFilterConfig(Context context, FilterDef filterDef)

 public ApplicationFilterConfig(Context context, FilterDef filterDef)
    throws ClassCastException, ClassNotFoundException,
           IllegalAccessException, InstantiationException,
           ServletException {
    super();
    this.context = context;
    setFilterDef(filterDef);
}

FilterDef

StandardContext

...

Host 和 Engine

 class StandardHost extends ContainerBase implements Deployer, Host{

 }

public class StandardEngine extends ContainerBase implements Engine {}

服务器组件和服务组件

public interface Server {
    public String getInfo();
    public NamingResources getGlobalNamingResources();
    public void setGlobalNamingResources
    (NamingResources globalNamingResources);
    public int getPort();
    public void setPort(int port);
    public String getShutdown();
    public void setShutdown(String shutdown);
    public void addService(Service service);
    public void await();
    public Service findService(String name);
    public Service[] findServices();
    public void removeService(Service service);
    public void initialize()
throws LifecycleException;
}


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;

}

Digester库

通过编写servlet.XML配置Tomcat,web.xml配置servlet/jsp引用，TOMCAT解析web.xml，基于web.xml配置 context对象，Disester库提供了支持

public final class ContextConfig implements LifecycleListener {
    private static Digester webDigester = createWebDigester();

    lifecycleEvent(){
    ...
    if (event.getType().equals(Lifecycle.START_EVENT))
        start();
    else if (event.getType().equals(Lifecycle.STOP_EVENT))
        stop();   
    }
    start() {
    ...
    defaultConfig();//处理DefaultWebXml = "conf/web.xml"
    applicationConfig();/WEB-INF/web.xml
    }
}

关闭钩子

    Runtime.getRuntime().addShutdownHook(Thread hook);
====================================================================
    //tomcat的关闭钩子
    protected class CatalinaShutdownHook extends Thread {
    public void run() {
        if (server != null) {
            try {
                ((Lifecycle) server).stop();
            } catch (LifecycleException e) {
                System.out.println("Catalina.stop: " + e);
                e.printStackTrace(System.out);
                if (e.getThrowable() != null) {
                    System.out.println("----- Root Cause -----");
                    e.getThrowable().printStackTrace(System.out);
                }
            }
        }
    }
}

TOMCAT启动

Catalinna

    (new Catalina()).process(args)

    public void process(String args[]) {
    setCatalinaHome();
    setCatalinaBase();
    try {
        if (arguments(args))
            execute();
    } catch (Exception e) {
        e.printStackTrace(System.out);
    }
}

protected void execute() throws Exception {
    if (starting)
        start();
    else if (stopping)
        stop();

}

server.await();

Bootstrap

启动TOMCAT的入口类之一。运行startup.bat或者startup.sh文件上时候，实际上调用了该类的main()方法。main方法会创建3个类在入侵，并实例化Catalina类。然后他调用Catalina实例的process方法

HostConfig

public class HostConfig
implements LifecycleListener, Runnable {
    public void lifecycleEvent(LifecycleEvent event) {

    // Identify the host we are associated with
    try {
        host = (Host) event.getLifecycle();
        if (host instanceof StandardHost) {
            int hostDebug = ((StandardHost) host).getDebug();
            if (hostDebug > this.debug) {
                this.debug = hostDebug;
            }
            setDeployXML(((StandardHost) host).isDeployXML());
            setLiveDeploy(((StandardHost) host).getLiveDeploy());
            setUnpackWARs(((StandardHost) host).isUnpackWARs());
        }
    } catch (ClassCastException e) {
        log(sm.getString("hostConfig.cce", event.getLifecycle()), e);
        return;
    }

    // Process the event that has occurred
    if (event.getType().equals(Lifecycle.START_EVENT))
        start();
    else if (event.getType().equals(Lifecycle.STOP_EVENT))
        stop();

}

    protected void start() {

    if (debug >= 1)
        log(sm.getString("hostConfig.start"));

    if (host.getAutoDeploy()) {
        deployApps();
    }

    if (isLiveDeploy()) {
    //动态部署
        threadStart();
    }

}
    protected void deployApps() {
    if (!(host instanceof Deployer))
        return;
    if (debug >= 1)
        log(sm.getString("hostConfig.deploying"));

    File appBase = appBase();
    if (!appBase.exists() || !appBase.isDirectory())
        return;
    String files[] = appBase.list();
    //部署描述符
    deployDescriptors(appBase, files);
    //部署WAR
    deployWARs(appBase, files);
    //部署目录
    deployDirectories(appBase, files);
}
}

Deployer 部署器接口

public interface Deployer  {
    public static final String PRE_INSTALL_EVENT = "pre-install";
    public static final String INSTALL_EVENT = "install";
    public static final String REMOVE_EVENT = "remove";
    public String getName();
    public void install(String contextPath, URL war) throws IOException;
    public void install(URL config, URL war) throws IOException;
    public Context findDeployedApp(String contextPath);
    public String[] findDeployedApps();
    public void remove(String contextPath) throws IOException;
    public void start(String contextPath) throws IOException;
    public void stop(String contextPath) throws IOException;
}

StandardHost

    private Deployer deployer = new StandardHostDeployer(this);

StandardHostDeployer

start(String contextPath)
stop(String contextPath)
install(String contextPath, URL war)
install(URL config, URL war)

Manager应用程序的servlet类

管理已部署的应用程序

JMX管理资源

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