Spring源码关于Spring MVC部分中文注释

Author: MrSorrow

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java

@@ -284,10 +284,10 @@ protected <T> T doGetBean(final String name, @Nullable final Class<T> requiredTy
 				throw new BeanCurrentlyInCreationException(beanName);
 			}
 
-			// Check if bean definition exists in this factory.
+			// 查看其父容器是否存在，这就决定了Spring父子容器的可见特性
 			BeanFactory parentBeanFactory = getParentBeanFactory();
 
-			// 如果beanDefinitionMap中也就是已经加载的类中不包括beanName则尝试从parentBeanFactory中检测
+			// 如果beanDefinitionMap中也就是已经加载的类中不包括beanName则尝试从父容器parentBeanFactory中检测
 			if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
 				// Not found -> check parent.
 				String nameToLookup = originalBeanName(name);

spring-mymvc/src/main/java/guo/ping/mvctest/context/MyContextListener.java

@@ -0,0 +1,29 @@
+package guo.ping.mvctest.context;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
+
+/**
+ * @description:
+ * @author: guoping wang
+ * @date: 2018/11/19 10:36
+ * @project: spring
+ */
+public class MyContextListener implements ServletContextListener {
+
+	private ServletContext servletContext;
+
+	@Override
+	public void contextInitialized(ServletContextEvent sce) {
+		servletContext = sce.getServletContext();
+		servletContext.setAttribute("name", "=========wgp========");
+		System.out.println("web application is starting...");
+	}
+
+	@Override
+	public void contextDestroyed(ServletContextEvent sce) {
+		System.out.println("servlet context is going to shut down...");
+		System.out.println(servletContext.getAttribute("name"));
+	}
+}

spring-mymvc/src/main/java/guo/ping/mvctest/controller/ModifyController.java

@@ -0,0 +1,33 @@
+package guo.ping.mvctest.controller;
+
+import org.springframework.web.servlet.ModelAndView;
+import org.springframework.web.servlet.mvc.AbstractController;
+import org.springframework.web.servlet.mvc.LastModified;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * @description: 测试Http缓存
+ * @author: guoping wang
+ * @date: 2018/11/21 11:18
+ * @project: spring
+ */
+public class ModifyController extends AbstractController implements LastModified {
+
+	private long lastModified;
+
+	@Override
+	protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception {
+		response.getWriter().write("test last modify");
+		return null;
+	}
+
+	@Override
+	public long getLastModified(HttpServletRequest request) {
+		if (lastModified == 0L) {
+			lastModified = System.currentTimeMillis();
+		}
+		return lastModified;
+	}
+}

spring-mymvc/src/main/java/guo/ping/mvctest/interceptor/CountTimeInterceptor.java

@@ -0,0 +1,36 @@
+package guo.ping.mvctest.interceptor;
+
+import org.springframework.web.servlet.HandlerInterceptor;
+import org.springframework.web.servlet.ModelAndView;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * @description:
+ * @author: guoping wang
+ * @date: 2018/11/21 16:10
+ * @project: spring
+ */
+public class CountTimeInterceptor implements HandlerInterceptor {
+
+	@Override
+	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
+		long startTime = System.currentTimeMillis();
+		request.setAttribute("startTime", startTime);
+		return true;
+	}
+
+	@Override
+	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
+		long startTime = (long) request.getAttribute("startTime");
+		request.removeAttribute("startTime");
+		long endTime = System.currentTimeMillis();
+		modelAndView.addObject("handingTime", endTime - startTime);
+	}
+
+	@Override
+	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
+
+	}
+}

spring-mymvc/src/main/resources/springmvc-config.xml

@@ -7,10 +7,19 @@
         <property name="mappings">
             <props>
                 <prop key="/userlist">userController</prop>
+				<prop key="/modify">modifyController</prop>
             </props>
         </property>
+		<property name="interceptors">
+			<list>
+				<ref bean="countTimeInterceptor" />
+			</list>
+		</property>
     </bean>
 
+	<bean id="countTimeInterceptor" class="guo.ping.mvctest.interceptor.CountTimeInterceptor" />
+
     <bean id="userController" class="guo.ping.mvctest.controller.UserController" />
+	<bean id="modifyController" class="guo.ping.mvctest.controller.ModifyController" />
 
 </beans>

spring-mymvc/src/main/webapp/WEB-INF/jsp/userlist.jsp

@@ -5,3 +5,4 @@
     　 <c:out value="${user.username}"/><br/>
     　 <c:out value="${user.age}"/><br/>
 </c:forEach>
+请求时间：${handingTime}

spring-web/src/main/java/org/springframework/web/context/ContextLoader.java

@@ -136,9 +136,10 @@ public class ContextLoader {
 
 	static {
 		// Load default strategy implementations from properties file.
-		// This is currently strictly internal and not meant to be customized
-		// by application developers.
+		// This is currently strictly internal and not meant to be customized by application developers.
+		// 从ContextLoader.properties配置文件中读取默认实现类
 		try {
+			// DEFAULT_STRATEGIES_PATH = "ContextLoader.properties"
 			ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, ContextLoader.class);
 			defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
 		}
@@ -247,6 +248,8 @@ public void setContextInitializers(@Nullable ApplicationContextInitializer<?>...
 
 
 	/**
+	 * 通过ServletContext对象初始化Spring的WebApplicationContext(父容器)
+	 * 该方法在ServletContext启动之后被调用，并准备好处理客户端请求
 	 * Initialize Spring's web application context for the given servlet context,
 	 * using the application context provided at construction time, or creating a new one
 	 * according to the "{@link #CONTEXT_CLASS_PARAM contextClass}" and
@@ -258,6 +261,8 @@ public void setContextInitializers(@Nullable ApplicationContextInitializer<?>...
 	 * @see #CONFIG_LOCATION_PARAM
 	 */
 	public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
+		// web.xml中存在多次ContextLoader定义就会抛出异常
+		// WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE=org.springframework.web.context.WebApplicationContext.ROOT
 		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 - " +
@@ -272,9 +277,9 @@ public WebApplicationContext initWebApplicationContext(ServletContext servletCon
 		long startTime = System.currentTimeMillis();
 
 		try {
-			// Store context in local instance variable, to guarantee that
-			// it is available on ServletContext shutdown.
+			// Store context in local instance variable, to guarantee that it is available on ServletContext shutdown.
 			if (this.context == null) {
+				// 创建Spring的WebApplicationContext
 				this.context = createWebApplicationContext(servletContext);
 			}
 			if (this.context instanceof ConfigurableWebApplicationContext) {
@@ -283,21 +288,24 @@ public WebApplicationContext initWebApplicationContext(ServletContext servletCon
 					// 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.
+						// The context instance was injected without an explicit parent -> determine parent for root web application context, if any.
+						// 看看是否有父容器，有的话设置给当前创建的容器，DispatcherServlet没有重写方法，直接返回null
 						ApplicationContext parent = loadParentContext(servletContext);
 						cwac.setParent(parent);
 					}
+					// 设置cwac相关属性并调用refresh
 					configureAndRefreshWebApplicationContext(cwac, servletContext);
 				}
 			}
+			// 记录在servletContext中
 			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) {
+				// 映射当前的类加载器与创建的实例到全局变量currentContextPerThread中
 				currentContextPerThread.put(ccl, this.context);
 			}
 
@@ -316,6 +324,7 @@ else if (ccl != null) {
 	}
 
 	/**
+	 * 创建WebApplicationContext
 	 * Instantiate the root WebApplicationContext for this loader, either the
 	 * default context class or a custom context class if specified.
 	 * <p>This implementation expects custom contexts to implement the
@@ -328,6 +337,7 @@ else if (ccl != null) {
 	 * @see ConfigurableWebApplicationContext
 	 */
 	protected WebApplicationContext createWebApplicationContext(ServletContext sc) {
+		// 判断WebApplicationContext具体要创建的子类类型
 		Class<?> contextClass = determineContextClass(sc);
 		if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {
 			throw new ApplicationContextException("Custom context class [" + contextClass.getName() +
@@ -337,6 +347,7 @@ protected WebApplicationContext createWebApplicationContext(ServletContext sc) {
 	}
 
 	/**
+	 * 判断决定WebApplicationContext具体要创建的子类类型
 	 * Return the WebApplicationContext implementation class to use, either the
 	 * default XmlWebApplicationContext or a custom context class if specified.
 	 * @param servletContext current servlet context
@@ -345,7 +356,9 @@ protected WebApplicationContext createWebApplicationContext(ServletContext sc) {
 	 * @see org.springframework.web.context.support.XmlWebApplicationContext
 	 */
 	protected Class<?> determineContextClass(ServletContext servletContext) {
+		// 获取ServletContext名称为“contextClass”的初始化参数的值
 		String contextClassName = servletContext.getInitParameter(CONTEXT_CLASS_PARAM);
+		// 如果web.xml中指定了WebApplicationContext具体要创建的子类类型，就用指定的，否则采用默认的
 		if (contextClassName != null) {
 			try {
 				return ClassUtils.forName(contextClassName, ClassUtils.getDefaultClassLoader());
@@ -356,6 +369,7 @@ protected Class<?> determineContextClass(ServletContext servletContext) {
 			}
 		}
 		else {
+			// 默认是org.springframework.web.context.support.XmlWebApplicationContext类型
 			contextClassName = defaultStrategies.getProperty(WebApplicationContext.class.getName());
 			try {
 				return ClassUtils.forName(contextClassName, ContextLoader.class.getClassLoader());
@@ -367,22 +381,30 @@ protected Class<?> determineContextClass(ServletContext servletContext) {
 		}
 	}
 
+	/**
+	 * 配置并刷新WebApplicationContext
+	 * @param wac
+	 * @param sc
+	 */
 	protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicationContext wac, ServletContext sc) {
 		if (ObjectUtils.identityToString(wac).equals(wac.getId())) {
-			// The application context id is still set to its original default value
-			// -> assign a more useful id based on available information
+			// The application context id is still set to its original default value -> assign a more useful id based on available information
+			// 替换WebApplicationContext容器的id，起一个更有意义的名字。如果ServletContext配置了则使用配置，否则默认规则起名
 			String idParam = sc.getInitParameter(CONTEXT_ID_PARAM);
 			if (idParam != null) {
 				wac.setId(idParam);
 			}
 			else {
-				// Generate default id...
+				// 生成默认id替换，WebApplicationContext全限定类名+":"+项目名
 				wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
 						ObjectUtils.getDisplayString(sc.getContextPath()));
 			}
 		}
 
+		// 将ServletContext设置给Spring容器
 		wac.setServletContext(sc);
+
+		// 设置Spring容器的配置文件路径
 		String configLocationParam = sc.getInitParameter(CONFIG_LOCATION_PARAM);
 		if (configLocationParam != null) {
 			wac.setConfigLocation(configLocationParam);
@@ -397,6 +419,8 @@ protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicati
 		}
 
 		customizeContext(sc, wac);
+
+		// 调用Spring容器的refresh()方法，加载配置文件
 		wac.refresh();
 	}
 

spring-web/src/main/java/org/springframework/web/context/ContextLoaderListener.java

@@ -20,6 +20,7 @@
 import javax.servlet.ServletContextListener;
 
 /**
+ * 启动Web容器时，自动装配ApplicationContext的配置信息
  * Bootstrap listener to start up and shut down Spring's root {@link WebApplicationContext}.
  * Simply delegates to {@link ContextLoader} as well as to {@link ContextCleanupListener}.
  *
@@ -97,15 +98,18 @@ public ContextLoaderListener(WebApplicationContext context) {
 
 	/**
 	 * Initialize the root web application context.
+	 * 该方法在ServletContext启动之后被调用，并准备好处理客户端请求
 	 */
 	@Override
 	public void contextInitialized(ServletContextEvent event) {
+		// 初始化WebApplicationContext
 		initWebApplicationContext(event.getServletContext());
 	}
 
 
 	/**
 	 * Close the root web application context.
+	 * 这个方法在ServletContext将要关闭的时候调用
 	 */
 	@Override
 	public void contextDestroyed(ServletContextEvent event) {

spring-web/src/main/java/org/springframework/web/context/request/ServletWebRequest.java

@@ -233,6 +233,7 @@ public boolean checkNotModified(@Nullable String etag, long lastModifiedTimestam
 
 		boolean validated = validateIfNoneMatch(etag);
 		if (!validated) {
+			// 比较If-Modified-Since和lastModifiedTimestamp
 			validateIfModifiedSince(lastModifiedTimestamp);
 		}
 
@@ -245,6 +246,7 @@ public boolean checkNotModified(@Nullable String etag, long lastModifiedTimestam
 			}
 			if (isHttpGetOrHead) {
 				if (lastModifiedTimestamp > 0 && parseDateValue(response.getHeader(LAST_MODIFIED)) == -1) {
+					// 更新Last-Modified为最新的更新时间
 					response.setDateHeader(LAST_MODIFIED, lastModifiedTimestamp);
 				}
 				if (StringUtils.hasLength(etag) && response.getHeader(ETAG) == null) {
@@ -321,7 +323,7 @@ private boolean validateIfModifiedSince(long lastModifiedTimestamp) {
 		if (ifModifiedSince == -1) {
 			return false;
 		}
-		// We will perform this validation...
+		// 如果当前请求中的If-Modified-Since时间晚于服务器时间，则认为是最新的，直接使用缓存
 		this.notModified = ifModifiedSince >= (lastModifiedTimestamp / 1000 * 1000);
 		return true;
 	}