http访问tomcat server的一个流程

Tomcat Server处理一个http请求的过程

假设来自客户的请求为：

http://localhost:8080/wsota/wsota_index.jsp

1) 请求被发送到本机端口8080，被在那里侦听的Coyote HTTP/1.1 Connector获得
2) Connector把该请求交给它所在的Service的Engine来处理，并等待来自Engine的回应
3) Engine获得请求localhost/wsota/wsota_index.jsp，匹配它所拥有的所有虚拟主机Host
4) Engine匹配到名为localhost的Host（即使匹配不到也把请求交给该Host处理，因为该Host被定义为该Engine的默认主机）
5) localhost Host获得请求/wsota/wsota_index.jsp，匹配它所拥有的所有Context
6) Host匹配到路径为/wsota的Context（如果匹配不到就把该请求交给路径名为”"的Context去处理）
7) path=”/wsota”的Context获得请求/wsota_index.jsp，在它的mapping table中寻找对应的servlet
8) Context匹配到URL PATTERN为*.jsp的servlet，对应于JspServlet类
9) 构造HttpServletRequest对象和HttpServletResponse对象，作为参数调用JspServlet的doGet或doPost方法
10)Context把执行完了之后的HttpServletResponse对象返回给Host
11)Host把HttpServletResponse对象返回给Engine
12)Engine把HttpServletResponse对象返回给Connector
13)Connector把HttpServletResponse对象返回给客户browser

 <?xml version='1.0' encoding='utf-8'?>
 <!--
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 -->
 <!-- Note:  A "Server" is not itself a "Container", so you may not
      define subcomponents such as "Valves" at this level.
      Documentation at /docs/config/server.html
  -->
 <Server port="8005" shutdown="SHUTDOWN">
   <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
   <!-- Security listener. Documentation at /docs/config/listeners.html
   <Listener className="org.apache.catalina.security.SecurityListener" />
   -->
   <!--APR library loader. Documentation at /docs/apr.html -->
   <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
   <!-- Prevent memory leaks due to use of particular java/javax APIs-->
   <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
   <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
   <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

   <!-- Global JNDI resources
        Documentation at /docs/jndi-resources-howto.html
   -->
   <GlobalNamingResources>
     <!-- Editable user database that can also be used by
          UserDatabaseRealm to authenticate users
     -->
     <Resource name="UserDatabase" auth="Container"
               type="org.apache.catalina.UserDatabase"
               description="User database that can be updated and saved"
               factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
               pathname="conf/tomcat-users.xml" />
   </GlobalNamingResources>

   <!-- A "Service" is a collection of one or more "Connectors" that share
        a single "Container" Note:  A "Service" is not itself a "Container",
        so you may not define subcomponents such as "Valves" at this level.
        Documentation at /docs/config/service.html
    -->
   <Service name="Catalina">

     <!--The connectors can use a shared executor, you can define one or more named thread pools-->
     <!--
     <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
         maxThreads="150" minSpareThreads="4"/>
     -->

     <!-- A "Connector" represents an endpoint by which requests are received
          and responses are returned. Documentation at :
          Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
          Java AJP  Connector: /docs/config/ajp.html
          APR (HTTP/AJP) Connector: /docs/apr.html
          Define a non-SSL/TLS HTTP/1.1 Connector on port 8080
     -->
     <Connector port="8080" protocol="HTTP/1.1"
                connectionTimeout="20000"
                redirectPort="8443" />
     <!-- A "Connector" using the shared thread pool-->
     <!--
     <Connector executor="tomcatThreadPool"
                port="8080" protocol="HTTP/1.1"
                connectionTimeout="20000"
                redirectPort="8443" />
     -->
     <!-- Define a SSL/TLS HTTP/1.1 Connector on port 8443
          This connector uses the NIO implementation that requires the JSSE
          style configuration. When using the APR/native implementation, the
          OpenSSL style configuration is required as described in the APR/native
          documentation -->
     <!--
     <Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol"
                maxThreads="150" SSLEnabled="true" scheme="https" secure="true"
                clientAuth="false" sslProtocol="TLS" />
     -->

     <!-- Define an AJP 1.3 Connector on port 8009 -->
     <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />

     <!-- An Engine represents the entry point (within Catalina) that processes
          every request.  The Engine implementation for Tomcat stand alone
          analyzes the HTTP headers included with the request, and passes them
          on to the appropriate Host (virtual host).
          Documentation at /docs/config/engine.html -->

     <!-- You should set jvmRoute to support load-balancing via AJP ie :
     <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
     -->
     <Engine name="Catalina" defaultHost="localhost">

       <!--For clustering, please take a look at documentation at:
           /docs/cluster-howto.html  (simple how to)
           /docs/config/cluster.html (reference documentation) -->
       <!--
       <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
       -->

       <!-- Use the LockOutRealm to prevent attempts to guess user passwords
            via a brute-force attack -->
       <Realm className="org.apache.catalina.realm.LockOutRealm">
         <!-- This Realm uses the UserDatabase configured in the global JNDI
              resources under the key "UserDatabase".  Any edits
              that are performed against this UserDatabase are immediately
              available for use by the Realm.  -->
         <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
                resourceName="UserDatabase"/>
       </Realm>

       <Host name="localhost"  appBase="webapps"
             unpackWARs="true" autoDeploy="true">

         <!-- SingleSignOn valve, share authentication between web applications
              Documentation at: /docs/config/valve.html -->
         <!--
         <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
         -->

         <!-- Access log processes all example.
              Documentation at: /docs/config/valve.html
              Note: The pattern used is equivalent to using pattern="common" -->
         <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
                prefix="localhost_access_log" suffix=".txt"
                pattern="%h %l %u %t &quot;%r&quot; %s %b" />

       </Host>
     </Engine>
   </Service>
 </Server>