标签：学习指南 web servletContext springframework listener context logger WebApplicationCo
事情是这样子的,看到一个关于springmvc源码解读的文章,他说tomcat是如何初始化ApplicationContext容器的,
springMVC源码分析--容器初始化（一）ContextLoaderListener
这个图,写的非常好
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/root-context.xml</param-value>
</context-param>
<!-- Creates the Spring Container shared by all Servlets and Filters -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<filter>
<filter-name>csrfFilter</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
<async-supported>true</async-supported>
</filter>
<filter-mapping>
<filter-name>csrfFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- Processes application requests -->
<servlet>
<servlet-name>appServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<async-supported>true</async-supported>
</servlet>
<servlet-mapping>
<servlet-name>appServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!-- Disables Servlet Container welcome file handling. Needed for compatibility with Servlet 3.0 and Tomcat 7.0 -->
<welcome-file-list>
<welcome-file></welcome-file>
</welcome-file-list>
</web-app>
这里主要表达的是添加了这个listener,那么这个listenter是tomcat加载的流程中加载的,
以前我是tomcat源码专家呢,那么在哪里加载的这个listner呢?那么就捋捋
这个是<listener>标签,那么那查看 WebRuleSet 类
在
digester.addCallMethod(prefix + "web-app/listener/listener-class",
"addApplicationListener", 0);
看到.这个是对于StanderContext对象进行添加, addApplicationListener
那么就要定位到StanderContext .addApplicationListener方法
类名 public class StandardContext
public void addApplicationListener(String listener) {
synchronized (applicationListeners) {
String results[] =new String[applicationListeners.length + 1];
for (int i = 0; i < applicationListeners.length; i++) {
if (listener.equals(applicationListeners[i]))
return;
results[i] = applicationListeners[i];
}
results[applicationListeners.length] = listener;
applicationListeners = results;
}
fireContainerEvent("addApplicationListener", listener);
// FIXME - add instance if already started?
}
接着看调用在哪里 StandandContext 3211 行
// Send application start events
if (debug >= 1)
log("Sending application start events");
setApplicationListeners(results);
Object instances[] = getApplicationListeners();
if (instances == null)
return (ok);
ServletContextEvent event =
new ServletContextEvent(getServletContext());
for (int i = 0; i < instances.length; i++) {
if (instances[i] == null)
continue;
if (!(instances[i] instanceof ServletContextListener))
continue;
ServletContextListener listener =
(ServletContextListener) instances[i];
try {
fireContainerEvent("beforeContextInitialized", listener);
listener.contextInitialized(event);
fireContainerEvent("afterContextInitialized", listener);
} catch (Throwable t) {
fireContainerEvent("afterContextInitialized", listener);
log(sm.getString("standardContext.listenerStart",
instances[i].getClass().getName()), t);
ok = false;
}
}
return (ok);
这就连上了,调用了listener.contextInitailized(event)方法
@Override
public void contextInitialized(ServletContextEvent event) {
initWebApplicationContext(event.getServletContext());
}
initWebApplicationContext 方法在他的父类
ContextLoader 上面
public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
if (servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE) != null) {
throw new IllegalStateException(
"Cannot initialize context because there is already a root application context present - " +
"check whether you have multiple ContextLoader* definitions in your web.xml!");
}
Log logger = LogFactory.getLog(ContextLoader.class);
servletContext.log("Initializing Spring root WebApplicationContext");
if (logger.isInfoEnabled()) {
logger.info("Root WebApplicationContext: initialization started");
}
long startTime = System.currentTimeMillis();
try {
// Store context in local instance variable, to guarantee that
// it is available on ServletContext shutdown.
if (this.context == null) {
this.context = createWebApplicationContext(servletContext);
}
if (this.context instanceof ConfigurableWebApplicationContext) {
ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) this.context;
if (!cwac.isActive()) {
// The context has not yet been refreshed -> provide services such as
// setting the parent context, setting the application context id, etc
if (cwac.getParent() == null) {
// The context instance was injected without an explicit parent ->
// determine parent for root web application context, if any.
ApplicationContext parent = loadParentContext(servletContext);
cwac.setParent(parent);
}
configureAndRefreshWebApplicationContext(cwac, servletContext);
}
}
servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);
ClassLoader ccl = Thread.currentThread().getContextClassLoader();
if (ccl == ContextLoader.class.getClassLoader()) {
currentContext = this.context;
}
else if (ccl != null) {
currentContextPerThread.put(ccl, this.context);
}
if (logger.isDebugEnabled()) {
logger.debug("Published root WebApplicationContext as ServletContext attribute with name [" +
WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE + "]");
}
if (logger.isInfoEnabled()) {
long elapsedTime = System.currentTimeMillis() - startTime;
logger.info("Root WebApplicationContext: initialization completed in " + elapsedTime + " ms");
}
return this.context;
}
catch (RuntimeException ex) {
logger.error("Context initialization failed", ex);
servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, ex);
throw ex;
}
catch (Error err) {
logger.error("Context initialization failed", err);
servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, err);
throw err;
}
}
以上标记为黄色的行就对应了,我张贴的逻辑图的过程,
看了的东西,真是记不住, 看到别人的分析,确实比我强呢,所以最近就加强看springmvc的东西吧
标签：学习指南,web,servletContext,springframework,listener,context,logger,WebApplicationCo 来源： https://www.cnblogs.com/zytcomeon/p/15703541.html
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