Tomcat之NIO架构源码分析

本文主要内容：

　　　　Tomcat-NIO启动源码分析，关于Tomcat响应一次HTTP请求进行详细的分析。Tomcat版本：9.0.6

启动Tomcat方式这里采取编程的方式，maven引入坐标

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-core</artifactId>
            <version>9.0.6</version>
        </dependency>

1.启动方法

        Tomcat tomcat = new Tomcat();
        Connector connector = new Connector();
        connector.setPort(8080);
        tomcat.setConnector(connector);
        tomcat.start();
        tomcat.getServer().await();

1. Connector的构造方法默认会使用Http11NioProtocol协议（NIO）来对客户端连接进行处理
2. Tomcat.start() 会初始化一个StandardServer和StandardService

2.LifecycleBase.start()  初始化与启动

@Override
    public final synchronized void start() throws LifecycleException {
        //state默认是 LifecycleState.NEW，首次执行时，先通过init（）方法实现初始化
        if (state.equals(LifecycleState.NEW)) {
            init();
        }
        try {
            setStateInternal(LifecycleState.STARTING_PREP, null, false);
            //初始化之后，开始启动tomcat服务器
            startInternal();　　　　　...........
    }

1. LifecycleBase 是 Tomcat中初始化的server的父类，当Tomcat的StandardServer调用start()方法时，会去执行LifecycleBase的 start 方法
2. LifecycleBase 中都保存 用volatile 修饰的state字段，该字段用来标识 Tomcat 启动时所处的状态，默认是 NEW
3. Tomcat 服务器的每个状态，都有对应的事件可以通过实现  LifecycleListener 接口在加载时都会被放进 lifecycleListeners 中

public enum LifecycleState {
    NEW(false, null),
    INITIALIZING(false, Lifecycle.BEFORE_INIT_EVENT),
    INITIALIZED(false, Lifecycle.AFTER_INIT_EVENT),
    STARTING_PREP(false, Lifecycle.BEFORE_START_EVENT),
    STARTING(true, Lifecycle.START_EVENT),
    STARTED(true, Lifecycle.AFTER_START_EVENT),
    STOPPING_PREP(true, Lifecycle.BEFORE_STOP_EVENT),
    STOPPING(false, Lifecycle.STOP_EVENT),
    STOPPED(false, Lifecycle.AFTER_STOP_EVENT),
    DESTROYING(false, Lifecycle.BEFORE_DESTROY_EVENT),
    DESTROYED(false, Lifecycle.AFTER_DESTROY_EVENT),
    FAILED(false, null);

    private final boolean available;
    private final String lifecycleEvent;

对应事件名

 1    /**
 2      * The LifecycleEvent type for the "component before init" event.
 3      */
 4     public static final String BEFORE_INIT_EVENT = "before_init";
 5
 6
 7     /**
 8      * The LifecycleEvent type for the "component after init" event.
 9      */
10     public static final String AFTER_INIT_EVENT = "after_init";
11
12
13     /**
14      * The LifecycleEvent type for the "component start" event.
15      */
16     public static final String START_EVENT = "start";
17
18
19     /**
20      * The LifecycleEvent type for the "component before start" event.
21      */
22     public static final String BEFORE_START_EVENT = "before_start";
23
24
25     /**
26      * The LifecycleEvent type for the "component after start" event.
27      */
28     public static final String AFTER_START_EVENT = "after_start";
29
30
31     /**
32      * The LifecycleEvent type for the "component stop" event.
33      */
34     public static final String STOP_EVENT = "stop";
35
36
37     /**
38      * The LifecycleEvent type for the "component before stop" event.
39      */
40     public static final String BEFORE_STOP_EVENT = "before_stop";
41
42
43     /**
44      * The LifecycleEvent type for the "component after stop" event.
45      */
46     public static final String AFTER_STOP_EVENT = "after_stop";
47
48
49     /**
50      * The LifecycleEvent type for the "component after destroy" event.
51      */
52     public static final String AFTER_DESTROY_EVENT = "after_destroy";
53
54
55     /**
56      * The LifecycleEvent type for the "component before destroy" event.
57      */
58     public static final String BEFORE_DESTROY_EVENT = "before_destroy";
59
60
61     /**
62      * The LifecycleEvent type for the "periodic" event.
63      */
64     public static final String PERIODIC_EVENT = "periodic";
65
66
67     /**
68      * The LifecycleEvent type for the "configure_start" event. Used by those
69      * components that use a separate component to perform configuration and
70      * need to signal when configuration should be performed - usually after
71      * {@link #BEFORE_START_EVENT} and before {@link #START_EVENT}.
72      */
73     public static final String CONFIGURE_START_EVENT = "configure_start";
74
75
76     /**
77      * The LifecycleEvent type for the "configure_stop" event. Used by those
78      * components that use a separate component to perform configuration and
79      * need to signal when de-configuration should be performed - usually after
80      * {@link #STOP_EVENT} and before {@link #AFTER_STOP_EVENT}.
81      */
82     public static final String CONFIGURE_STOP_EVENT = "configure_stop";

public enum LifecycleState {    NEW(false, null),    INITIALIZING(false, Lifecycle.BEFORE_INIT_EVENT),    INITIALIZED(false, Lifecycle.AFTER_INIT_EVENT),    STARTING_PREP(false, Lifecycle.BEFORE_START_EVENT),    STARTING(true, Lifecycle.START_EVENT),    STARTED(true, Lifecycle.AFTER_START_EVENT),    STOPPING_PREP(true, Lifecycle.BEFORE_STOP_EVENT),    STOPPING(false, Lifecycle.STOP_EVENT),    STOPPED(false, Lifecycle.AFTER_STOP_EVENT),    DESTROYING(false, Lifecycle.BEFORE_DESTROY_EVENT),    DESTROYED(false, Lifecycle.AFTER_DESTROY_EVENT),    FAILED(false, null);

    private final boolean available;    private final String lifecycleEvent;

原文地址：https://www.cnblogs.com/coding400/p/10526993.html