springmvc之DispatcherServlet配置

DispatcherServlet是前置控制器，配置在web.xml文件中的。拦截匹配的请求，Servlet拦截匹配规则要自己定义，把拦截下来的请求，依据相应的规则分发到目标Controller来处理，是配置spring MVC的第一步。

 参考：https://baike.baidu.com/item/DispatcherServlet/12740507?fr=aladdin

 怎么没有初始化参数呢？

可以发现，org.geoserver.ows.dispatcher其实被很多类继承。。例如GWC类。。搜org.geoserver.gwc.GWC。。可以发现它作为bean配置在context.xml中。这与之前学的dispatch应该配置在web.xml中不一致

public class GWC implements DisposableBean, InitializingBean, ApplicationContextAware {

}

会发现geoserver的web工程web.xml中dispatcherservlet没有配置参数，默认所有的/网址都交由dispatchServlet来处理。。默认springmvc-servlet.xml又为空。。那么会智能的找到ows.dispatcher吗？

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
    <display-name>GeoServer</display-name>
  
      <context-param>
    <param-name>serviceStrategy</param-name>
    <!-- Meaning of the different values :
         
         PARTIAL-BUFFER2
         - Partially buffers the first xKb to disk. Once that has buffered, the the 
           result is streamed to the user. This will allow for most errors to be caught
           early. 
           
         BUFFER
         - stores the entire response in memory first, before sending it off to
           the user (may run out of memory)

         SPEED
         - outputs directly to the response (and cannot recover in the case of an
           error)

         FILE
         - outputs to the local filesystem first, before sending it off to the user
      -->
    <param-value>PARTIAL-BUFFER2</param-value>
  </context-param>
  
  <context-param>
    <!-- see comments on the PARTIAL-BUFFER strategy -->
    <!-- this sets the size of the buffer.  default is "50" = 50kb -->

    <param-name>PARTIAL_BUFFER_STRATEGY_SIZE</param-name>
    <param-value>50</param-value>
  </context-param>
  
  <!--Can be true or false (defaults to: false). -->
  <!--When true the JSONP (text/javascript) output format is enabled -->
  <!--
  <context-param>
    <param-name>ENABLE_JSONP</param-name>
    <param-value>true</param-value>
  </context-param>
  -->
    <!-- 
    <context-param>
      <param-name>PROXY_BASE_URL</param-name>
      <param-value>http://82.58.146.45/geoserver</param-value>
    </context-param>
     -->
   
     <!--
    <context-param>
       <param-name>GEOSERVER_DATA_DIR</param-name>
        <param-value>C:\eclipse\workspace\geoserver_trunk\cite\confCiteWFSPostGIS</param-value>
    </context-param> 
   -->
    
    <!-- pick up all spring application contexts -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath*:/applicationContext.xml classpath*:/applicationSecurityContext.xml</param-value>
    </context-param>
    
    <filter>
     <filter-name>FlushSafeFilter</filter-name>
     <filter-class>org.geoserver.filters.FlushSafeFilter</filter-class>
    </filter>
     
    <filter>
      <filter-name>Set Character Encoding</filter-name>
      <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
      <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
      </init-param>
    </filter>

    <filter>
     <filter-name>SessionDebugger</filter-name>
     <filter-class>org.geoserver.filters.SessionDebugFilter</filter-class>
    </filter>

    <filter>
    <filter-name>filterChainProxy</filter-name>     
     <filter-class> org.springframework.web.filter.DelegatingFilterProxy</filter-class>
    </filter>

    <filter>
      <filter-name>xFrameOptionsFilter</filter-name>
      <filter-class>org.geoserver.filters.XFrameOptionsFilter</filter-class>
    </filter>

   <filter>
     <filter-name>GZIP Compression Filter</filter-name>
     <filter-class>org.geoserver.filters.GZIPFilter</filter-class>
     <init-param>
         <!-- The compressed-types parameter is a comma-separated list of regular expressions.
              If a mime type matches any of the regular expressions then it will be compressed.
              -->
         <param-name>compressed-types</param-name>
         <param-value>text/.*,.*xml.*,application/json,application/x-javascript</param-value>
     </init-param>
   </filter>

   <filter>
     <filter-name>Request Logging Filter</filter-name>
     <filter-class>org.geoserver.filters.LoggingFilter</filter-class>
     <init-param>
         <!-- The 'enabled' parameter is a boolean value, "true" (case-insensitive) for true or
              any other value for false.  If enabled, then the logging will be performed;
              otherwise the logging filter will have no effect.  If not specified, this 
              parameter defaults to false.
              -->
         <param-name>enabled</param-name>
         <param-value>false</param-value>
     </init-param>
     <init-param>
         <!-- The 'log-request-headers' parameter is a boolean value, "true" (case-insensitive) for
              true or any other value for false.  If enabled, then the logging will include the HTTP 
              headers of requests.  If not specified, this parameter defaults to false.
              -->
         <param-name>log-request-headers</param-name>
         <param-value>false</param-value>
     </init-param>  
     <init-param>
     <!-- The 'log-request-bodies' parameter is a boolean value, "true" (case-insensitive) for
          true or any other value for false.  If enabled, then the logging will include the body
          of POST and PUT requests.  If not specified, this parameter defaults to false.
          Note that this may noticeably degrade responsiveness of your geoserver since it will
          not begin to process requests until the entire request body has been received by the 
          server.
          -->
     <param-name>log-request-bodies</param-name>
     <param-value>false</param-value>
     </init-param>
   </filter>
   
   <filter>
     <filter-name>Advanced Dispatch Filter</filter-name>
     <filter-class>org.geoserver.platform.AdvancedDispatchFilter</filter-class>
     <!-- 
     This filter allows for a single mapping to the spring dispatcher. However using /* as a mapping
     in a servlet mapping causes the servlet path to be "/" of the request. This causes problems with
     library like wicket and restlet. So this filter fakes the servlet path by assuming the first 
     component of the path is the mapped path. 
     -->
   </filter>
   
   <filter>
    <filter-name>Spring Delegating Filter</filter-name>
    <filter-class>org.geoserver.filters.SpringDelegatingFilter</filter-class>
    <!--
    This filter allows for filters to be loaded via spring rather than 
    registered here in web.xml.  One thing to note is that for such filters 
    init() is not called. INstead any initialization is performed via spring 
    ioc.
    -->
   </filter>
   
   <filter>
     <filter-name>Thread locals cleanup filter</filter-name>
     <filter-class>org.geoserver.filters.ThreadLocalsCleanupFilter</filter-class>
     <!-- 
     This filter cleans up thread locals Geotools is setting up for concurrency and performance
     reasons 
     -->
   </filter>

   <!-- Uncomment following filter to enable CORS in Jetty. Do not forget the second config block further down.
    <filter>
      <filter-name>cross-origin</filter-name>
      <filter-class>org.eclipse.jetty.servlets.CrossOriginFilter</filter-class>
      <init-param>
        <param-name>chainPreflight</param-name>
        <param-value>false</param-value>
      </init-param>
      <init-param>
        <param-name>allowedOrigins</param-name>
        <param-value>*</param-value>
      </init-param>
      <init-param>
        <param-name>allowedMethods</param-name>
        <param-value>GET,POST,PUT,DELETE,HEAD,OPTIONS</param-value>
      </init-param>
      <init-param>
        <param-name>allowedHeaders</param-name>
        <param-value>*</param-value>
      </init-param>
    </filter>
    -->
    
   <!-- Uncomment following filter to enable CORS in Tomcat. Do not forget the second config block further down.
    <filter>
      <filter-name>cross-origin</filter-name>
      <filter-class>org.apache.catalina.filters.CorsFilter</filter-class>
      <init-param>
        <param-name>cors.allowed.origins</param-name>
        <param-value>*</param-value>
      </init-param>
      <init-param>
        <param-name>cors.allowed.methods</param-name>
        <param-value>GET,POST,PUT,DELETE,HEAD,OPTIONS</param-value>
      </init-param>
      <init-param>
        <param-name>cors.allowed.headers</param-name>
        <param-value>*</param-value>
      </init-param>
    </filter>
    -->

    <!-- 
      THIS FILTER MAPPING MUST BE THE FIRST ONE, otherwise we end up with ruined chars in the input from the GUI
      See the "Note" in the Tomcat character encoding guide:
      http://wiki.apache.org/tomcat/FAQ/CharacterEncoding
    -->
    <filter-mapping>
      <filter-name>Set Character Encoding</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>
   
   <!-- Uncomment following filter to enable CORS
    <filter-mapping>
        <filter-name>cross-origin</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    -->
   
    <filter-mapping>
      <filter-name>FlushSafeFilter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <filter-mapping>
      <filter-name>SessionDebugger</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>

    <filter-mapping>
      <filter-name>GZIP Compression Filter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>

    <filter-mapping>
      <filter-name>xFrameOptionsFilter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <filter-mapping>
      <filter-name>Request Logging Filter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>
   
    <!-- 
      If you want to use your security system comment out this one too
    -->
    <filter-mapping>
      <filter-name>filterChainProxy</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <filter-mapping>
      <filter-name>Advanced Dispatch Filter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>

    <filter-mapping>
      <filter-name>Spring Delegating Filter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <filter-mapping>
      <filter-name>Thread locals cleanup filter</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <!-- general initializer, should be first thing to execute -->
    <listener>
      <listener-class>org.geoserver.GeoserverInitStartupListener</listener-class>
    </listener>
    
    <!-- logging initializer, should execute before spring context startup -->
    <listener>
      <listener-class>org.geoserver.logging.LoggingStartupContextListener</listener-class>
    </listener>
  
    <!--  spring context loader -->
    <listener>
      <listener-class>org.geoserver.platform.GeoServerContextLoaderListener</listener-class>
    </listener>
    
    <!--  http session listener proxy -->
    <listener>
      <listener-class>org.geoserver.platform.GeoServerHttpSessionListenerProxy</listener-class>
    </listener>

    <!-- request context listener for session-scoped beans -->
    <listener>
        <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>
    
    <!-- spring dispatcher servlet, dispatches all incoming requests -->
    <servlet>
      <servlet-name>dispatcher</servlet-name>
      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    </servlet>
    
    <!-- single mapping to spring, this only works properly if the advanced dispatch filter is 
         active映射到spring，这个只有在高级dispatch filter激活的情况下才能运行良好 -->
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
    
    <mime-mapping>
      <extension>xsl</extension>
      <mime-type>text/xml</mime-type>
    </mime-mapping>
    <mime-mapping>
      <extension>sld</extension>
      <mime-type>text/xml</mime-type>
    </mime-mapping>
    <mime-mapping>
      <extension>json</extension>
      <mime-type>application/json</mime-type>
    </mime-mapping>
  
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>
    
</web-app>

先定义filter，然后设置filter-mapping。。