Service组件 - 969251639/study GitHub Wiki

从上图可以看到Service包含了两部分，一个时Engine，也就是容器，还有一个时连接器Connector，用于接受外部的连接

在tomcat启动时会解析server.xml，其中会给Server注入一个org.apache.catalina.core.StandardService类

        digester.addObjectCreate("Server/Service",
                                 "org.apache.catalina.core.StandardService",
                                 "className");
        digester.addSetProperties("Server/Service");
        digester.addSetNext("Server/Service",
                            "addService",
                            "org.apache.catalina.Service");

这时候Server就有了Service，然后就能启动service，同理，service下面的Connector和Engine也是类似的注入方式

        ...
        //Executor
        digester.addObjectCreate("Server/Service/Executor",
                         "org.apache.catalina.core.StandardThreadExecutor",
                         "className");
        digester.addSetProperties("Server/Service/Executor");

        digester.addSetNext("Server/Service/Executor",
                            "addExecutor",
                            "org.apache.catalina.Executor");
        ...

        digester.addRule("Server/Service/Connector",
                         new ConnectorCreateRule());
        digester.addRule("Server/Service/Connector",
                         new SetAllPropertiesRule(new String[]{"executor"}));
        digester.addSetNext("Server/Service/Connector",
                            "addConnector",
                            "org.apache.catalina.connector.Connector");
        ...
        digester.addRuleSet(new EngineRuleSet("Server/Service/"));
        digester.addRuleSet(new HostRuleSet("Server/Service/Engine/"));
        ...

注：后面的所有的相关组件都是类似创建手段

接下来看service的initInternal做了什么

    @Override
    protected void initInternal() throws LifecycleException {

        super.initInternal();

        if (container != null) {
            container.init();
        }

        // Initialize any Executors
        for (Executor executor : findExecutors()) {
            if (executor instanceof JmxEnabled) {
                ((JmxEnabled) executor).setDomain(getDomain());
            }
            executor.init();
        }

        // Initialize mapper listener
        mapperListener.init();

        // Initialize our defined Connectors
        synchronized (connectorsLock) {
            for (Connector connector : connectors) {
                try {
                    connector.init();
                } catch (Exception e) {
                    String message = sm.getString(
                            "standardService.connector.initFailed", connector);
                    log.error(message, e);

                    if (Boolean.getBoolean("org.apache.catalina.startup.EXIT_ON_INIT_FAILURE"))
                        throw new LifecycleException(message);
                }
            }
        }
    }

主要做了三件事

1. 初始化容器container（也就是Engine）
2. 初始化线程池executor
3. 初始化下面的多个connector连接器

而与之对应的start也是一样

    @Override
    protected void startInternal() throws LifecycleException {

        if(log.isInfoEnabled())
            log.info(sm.getString("standardService.start.name", this.name));
        setState(LifecycleState.STARTING);

        // Start our defined Container first
        if (container != null) {
            synchronized (container) {
                container.start();
            }
        }

        synchronized (executors) {
            for (Executor executor: executors) {
                executor.start();
            }
        }

        mapperListener.start();

        // Start our defined Connectors second
        synchronized (connectorsLock) {
            for (Connector connector: connectors) {
                try {
                    // If it has already failed, don't try and start it
                    if (connector.getState() != LifecycleState.FAILED) {
                        connector.start();
                    }
                } catch (Exception e) {
                    log.error(sm.getString(
                            "standardService.connector.startFailed",
                            connector), e);
                }
            }
        }
    }

1. 启动容器container（也就是Engine）
2. 启动线程池executor
3. 启动下面的多个connector连接器