springmvc之DispatcherServlet配置

DispatcherServlet是前置控制器，配置在web.xml文件中的。攔截匹配的請求，Servlet攔截匹配規則要自己定義，把攔截下來的請求，依據相應的規則分發到目標Controller來處理，是配置spring MVC的第一步。

 

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

 怎么沒有初始化參數呢？

可以發現，org.geoserver.ows.dispatcher其實被很多類繼承。。例如GWC類。。搜org.geoserver.gwc.GWC。。可以發現它作為bean配置在context.xml中。這與之前學的dispatch應該配置在web.xml中不一致

public class GWC implements DisposableBean, InitializingBean, ApplicationContextAware {

}

會發現geoserver的web工程web.xml中dispatcherservlet沒有配置參數，默認所有的/網址都交由dispatchServlet來處理。。默認springmvc-servlet.xml又為空。。那么會智能的找到ows.dispatcher嗎？

<?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，這個只有在高級dispatch filter激活的情況下才能運行良好 -->
    <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>

先定義filter，然后設置filter-mapping。。