标签：springboot tomcat webServer 源码 Tomcat ex context new
springboot中嵌入tomcat原理分析
首先要了解tomcat本身，否则springboot内嵌tomcat就很难分析。关于tomcat的源码会后续更新。
本文主要先简单分析一下springboot内嵌tomcat的源码，深入了解以后再更新。
还是先从springboot的启动入口run（）方法开始分析。。。。。。
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
configureHeadlessProperty();
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
configureIgnoreBeanInfo(environment);
Banner printedBanner = printBanner(environment);
//创建应用上下文
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
prepareContext(context, environment, listeners, applicationArguments, printedBanner);
//刷新应用上下文，完成spring容器的初始化，也会加载tomcat
refreshContext(context);
afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
}
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}
进入refreshContext（）----》ServletWebServerApplicationContext.refreshContext()方法：
进入super.refresh()方法后，进入到spring的源码中了，在进入onRefreshContext（）方法---》ServletWebServerApplicationContext.onRefreshContext()方法
@Override
protected void onRefresh() {
super.onRefresh();
try {
//创建web实例
createWebServer();
}
catch (Throwable ex) {
throw new ApplicationContextException("Unable to start web server", ex);
}
}
进入createWebServer()方法：
private void createWebServer() {
WebServer webServer = this.webServer;
ServletContext servletContext = getServletContext();
if (webServer == null && servletContext == null) {
//获取webServer的工厂对象
ServletWebServerFactory factory = getWebServerFactory();
//获得具体的webServer对象------>TomcatWebServer
this.webServer = factory.getWebServer(getSelfInitializer());
getBeanFactory().registerSingleton("webServerGracefulShutdown",
new WebServerGracefulShutdownLifecycle(this.webServer));
getBeanFactory().registerSingleton("webServerStartStop",
new WebServerStartStopLifecycle(this, this.webServer));
}
else if (servletContext != null) {
try {
getSelfInitializer().onStartup(servletContext);
}
catch (ServletException ex) {
throw new ApplicationContextException("Cannot initialize servlet context", ex);
}
}
initPropertySources();
}
再看一下getWebServer()里的逻辑---》直接进入TomcatServletWebServerFactory.getWebServer()中
public WebServer getWebServer(ServletContextInitializer... initializers) {
if (this.disableMBeanRegistry) {
Registry.disableRegistry();
}
//创建tomcat对象
Tomcat tomcat = new Tomcat();
File baseDir = (this.baseDirectory != null) ? this.baseDirectory : createTempDir("tomcat");
tomcat.setBaseDir(baseDir.getAbsolutePath());
//创建连接器
Connector connector = new Connector(this.protocol);
connector.setThrowOnFailure(true);
//service关联连接器
tomcat.getService().addConnector(connector);
customizeConnector(connector);
tomcat.setConnector(connector);
tomcat.getHost().setAutoDeploy(false);
//配置Engin
configureEngine(tomcat.getEngine());
for (Connector additionalConnector : this.additionalTomcatConnectors) {
tomcat.getService().addConnector(additionalConnector);
}
prepareContext(tomcat.getHost(), initializers);
//返回获取的TomcatWebServer对象
return getTomcatWebServer(tomcat);
}
然后进入到getTomcatWebServer（）方法中
protected TomcatWebServer getTomcatWebServer(Tomcat tomcat) {
//直接创建，我们需要看构造方法
return new TomcatWebServer(tomcat, getPort() >= 0, getShutdown());
}
TomcatWebServer的构造方法：
public TomcatWebServer(Tomcat tomcat, boolean autoStart, Shutdown shutdown) {
Assert.notNull(tomcat, "Tomcat Server must not be null");
this.tomcat = tomcat;
this.autoStart = autoStart;
this.gracefulShutdown = (shutdown == Shutdown.GRACEFUL) ? new GracefulShutdown(tomcat) : null;
//初始化 重点
initialize();
}
进入initialize()方法：
private void initialize() throws WebServerException {
logger.info("Tomcat initialized with port(s): " + getPortsDescription(false));
synchronized (this.monitor) {
try {
addInstanceIdToEngineName();
Context context = findContext();
context.addLifecycleListener((event) -> {
if (context.equals(event.getSource()) && Lifecycle.START_EVENT.equals(event.getType())) {
// Remove service connectors so that protocol binding doesn't
// happen when the service is started.
removeServiceConnectors();
}
});
// Start the server to trigger initialization listeners
//启动Tomcat通过发布事件触发一些Listener的初始化
this.tomcat.start(); //启动tomcat
// We can re-throw failure exception directly in the main thread
rethrowDeferredStartupExceptions();
try {
ContextBindings.bindClassLoader(context, context.getNamingToken(), getClass().getClassLoader());
}
catch (NamingException ex) {
// Naming is not enabled. Continue
}
// Unlike Jetty, all Tomcat threads are daemon threads. We create a
// blocking non-daemon to stop immediate shutdown
startDaemonAwaitThread();
}
catch (Exception ex) {
stopSilently();
destroySilently();
throw new WebServerException("Unable to start embedded Tomcat", ex);
}
}
}
进入start()方法：
public void start() throws LifecycleException {
this.getServer();
this.server.start();
}
到这儿后面的逻辑其实就是Tomcat自身启动的逻辑了。这就需要你的Tomcat基础了，到这SpringBoot启动是如何内嵌Tomcat容器的到这儿就结束了哦。
springboot源码大致流程也就结束了。后面会有一些细节补充的内容。
标签：springboot,tomcat,webServer,源码,Tomcat,ex,context,new 来源： https://www.cnblogs.com/bentuzi/p/16094932.html
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