访问 Tomcat 发布的应用中不存在的页面或 URL 中包含特殊字符时，会看到下面这样的界面：

http://localhost:8080/not-exist

http://localhost:8080/([%5E

如遇安全扫描等场景希望不暴露 Tomcat 版本信息时，可以在其配置文件 conf/server.xml 中的 Host 元素内添加如下内容：

<Valve className="org.apache.catalina.valves.ErrorReportValve" 
       showReport="false" showServerInfo="false" />

以截图中使用的 Tomcat 10.1.15 版本为例，原始的去掉注释部分的 conf/server.xml 内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<Server port="8005" shutdown="SHUTDOWN">
  <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <GlobalNamingResources>
    <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>

  <Service name="Catalina">

    <Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443"
               maxParameterCount="1000"
               />
    <Engine name="Catalina" defaultHost="localhost">

      <Realm className="org.apache.catalina.realm.LockOutRealm">
        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
               resourceName="UserDatabase"/>
      </Realm>

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

        <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>

添加 Valve 后为：

<?xml version="1.0" encoding="UTF-8"?>
<Server port="8005" shutdown="SHUTDOWN">
  <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <GlobalNamingResources>
    <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>

  <Service name="Catalina">

    <Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443"
               maxParameterCount="1000"
               />
    <Engine name="Catalina" defaultHost="localhost">

      <Realm className="org.apache.catalina.realm.LockOutRealm">
        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
               resourceName="UserDatabase"/>
      </Realm>

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

        <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" />

        <Valve className="org.apache.catalina.valves.ErrorReportValve" 
               showReport="false" showServerInfo="false" />

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

隐藏后效果如下：

Error Report Valve

关于 ErrorReportValve 的用法，可参照 Tomcat 对应版本的官方文档，如：https://tomcat.apache.org/tomcat-10.1-doc/config/valve.html#Error_Report_Valve

特殊字符

如果不想上例中的包含特殊字符的请求（http://localhost:8080/([%5E）被 Tomcat 拒绝至 400 错误页，可通过 Tomcat HTTP Connector 的 标准实现 中的 relaxedPathChars 和 relaxedQueryChars 参数配置在请求路径和查询字符串中允许的特殊字符，例如下面的配置可以使 http://localhost:8080/([%5E 请求跳转到 404 错误页不是默认的 400 错误页。

<Connector port="8080" protocol="HTTP/1.1"
            connectionTimeout="20000"
            redirectPort="8443"
            maxParameterCount="1000"
            relaxedPathChars="&lt;>[\]^`{|}"
            />

系统参数 中的 tomcat.util.http.parser.HttpParser.requestTargetAllow 配置项在 Tomcat 8 中声明弃用，被 relaxedPathChars 和 relaxedQueryChars Connector 属性取代。