1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 

/** * Standard implementation of <code>ServletContext</code> that represents * a web application's execution environment. An instance of this class is * associated with each instance of <code>StandardContext</code>. * 代表web应用程序的执行环境。这个类的一个实例是 *与StandardContext的每个实例关联。 * @author Craig R. McClanahan * @author Remy Maucherat */ public class ApplicationContext implements ServletContext { protected static final boolean STRICT_SERVLET_COMPLIANCE;///翻译为是否严格遵守 protected static final boolean GET_RESOURCE_REQUIRE_SLASH;//我的蹩脚英语翻译为获取资源是否需要斜线。 static { STRICT_SERVLET_COMPLIANCE = Globals.STRICT_SERVLET_COMPLIANCE; String requireSlash = System.getProperty("org.apache.catalina.core.ApplicationContext.GET_RESOURCE_REQUIRE_SLASH"); if (requireSlash == null) { GET_RESOURCE_REQUIRE_SLASH = STRICT_SERVLET_COMPLIANCE; } else { GET_RESOURCE_REQUIRE_SLASH = Boolean.parseBoolean(requireSlash); } } 

1 

public static final boolean STRICT_SERVLET_COMPLIANCE =Boolean.parseBoolean(System.getProperty("org.apache.catalina.STRICT_SERVLET_COMPLIANCE", "false")); 

1 2 3 4 

而HttpServlet即是大部分请求的处理对象，嵌入式引擎----嵌入式容器---- webfilter ---weblistener javax.servlet.ServletContext#addServlet(java.lang.String, java.lang.Class<? extends javax.servlet.Servlet>)返回一个ServletRegistration对象，可用于进一步 配置已注册的servlet javax.servlet.ServletRegistration 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 

public interface ServletRegistration extends Registration { /** * TODO * @param urlPatterns The URL patterns that this Servlet should be mapped to * @return TODO * @throws IllegalArgumentException if urlPattern is null or empty * @throws IllegalStateException if the associated ServletContext has * already been initialised */URL必须映射 public Set<String> addMapping(String... urlPatterns); public Collection<String> getMappings(); public String getRunAsRole(); public static interface Dynamic extends ServletRegistration, Registration.Dynamic { public void setLoadOnStartup(int loadOnStartup); public Set<String> setServletSecurity(ServletSecurityElement constraint); public void setMultipartConfig(MultipartConfigElement multipartConfig); public void setRunAsRole(String roleName); } } 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 

@Override public ServletRegistration.Dynamic addServlet(String servletName, String className) { return addServlet(servletName, className, null, null); } @Override public ServletRegistration.Dynamic addServlet(String servletName, Servlet servlet) { return addServlet(servletName, null, servlet, null); } @Override public ServletRegistration.Dynamic addServlet(String servletName, Class<? extends Servlet> servletClass) { return addServlet(servletName, servletClass.getName(), null, null); } 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 

 private static final String METHOD_DELETE = "DELETE"; private static final String METHOD_HEAD = "HEAD"; private static final String METHOD_GET = "GET"; private static final String METHOD_OPTIONS = "OPTIONS"; private static final String METHOD_POST = "POST"; private static final String METHOD_PUT = "PUT"; private static final String METHOD_TRACE = "TRACE"; protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String method = req.getMethod(); //GET if (method.equals(METHOD_GET)) { long lastModified = getLastModified(req); if (lastModified == -1) { // servlet doesn't support if-modified-since, no reason // to go through further expensive logic doGet(req, resp); } else { long ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE); if (ifModifiedSince < lastModified) { // If the servlet mod time is later, call doGet() // Round down to the nearest second for a proper compare // A ifModifiedSince of -1 will always be less maybeSetLastModified(resp, lastModified); doGet(req, resp); } else { resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED); } } } else if (method.equals(METHOD_HEAD)) { long lastModified = getLastModified(req); maybeSetLastModified(resp, lastModified); doHead(req, resp); } else if (method.equals(METHOD_POST)) { doPost(req, resp); } else if (method.equals(METHOD_PUT)) { doPut(req, resp); } else if (method.equals(METHOD_DELETE)) { doDelete(req, resp); } else if (method.equals(METHOD_OPTIONS)) { doOptions(req,resp); } else if (method.equals(METHOD_TRACE)) { doTrace(req,resp); //There's no need to override this method. 没有必要~ } else { // // Note that this means NO servlet supports whatever // method was requested, anywhere on this server. // String errMsg = lStrings.getString("http.method_not_implemented"); Object[] errArgs = new Object[1]; errArgs[0] = method; errMsg = MessageFormat.format(errMsg, errArgs); resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg); } } protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String protocol = req.getProtocol(); String msg = lStrings.getString("http.method_post_not_supported"); if (protocol.endsWith("1.1")) { resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg); } else { resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg); } } 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 

Tomcat与SpringMVC的结合点：ApplicationFilterChain与DispatcherServlet（继承于FrameworkServlet）； （1）所有配置了路由信息的处理方法最终都是通过反射的方式进行调用的； （2）在Java8中，反射方法调用最终落脚于NativeMethodAccessorImpl类的native方法： private static native Object invoke0(Method var0, Object var1, Object[] var2); 在此处与JVM底层交互，实现跨代码衔接执行； （3）观察到的比较重要的设计模式：职责链模式（ApplicationFilterChain）、委派模式（DelegatingFilterProxy）、 工厂模式、策略模式、代理模式（FilterChainProxy）、外观模式、适配器模式（HandlerAdapter）； （4）Tomcat与SpringMVC的结合点：ApplicationFilterChain与DispatcherServlet（继承于FrameworkServlet）； （5）在集成了Tomcat的SpringBoot项目中，先启动的不是Tomcat，而是Spring，Spring的工厂（默认DefaultListableBeanFactory） 读取注解完成各类Bean（WebApplicationContext、securityFilterChainRegistration、dispatcherServletRegistration、各类FilterInitializer与Filter） 的初始化，放入IoC容器，然后做路由Mapping，创建FilterChain，开启JMX等； （6）Servlet、Filter是单实例多线程的，成员变量线程不安全，方法内局部变量线程安全；SingleThreadModel采用同步/实例池的方式来确保不会有两个线程同时执行servlet的service方法，但已被弃用，需自行确保成员变量线程安全； ———————————————— 版权声明：本文为CSDN博主「wanxu」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。 原文链接：https://blog.csdn.net/wanxu/article/details/