tomcat配置访问不带项目名，以及每次启动tomcat启动服务两次

如将aaa.war放到webapps下,启动tomcat后，默认方式下访问该项目是需要带项目名称的，例http://localhost:8080/aaa/。
现在需要改成这样访问http://localhost:8080/。
修改tomcat的server.xml文件，增加如下配置<Context path="/" docBase="aaa" reloadable="false"/>，修改后host部分如下：

<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" />

       <Context path="/" docBase="aaa" reloadable="false"/>

      </Host>

此时每次启动tomcat观察日志都会发现应用加载了两次，什么原因呢？

虚拟目录引起的问题，我们在Host标签里配置了appBase="webapps"，tomcat加载一次应用。在里配置了一次docBase，tomcat又去加载一次应用。

将appBase="webapps"置为appBase=""，docBase="aaa"置为docBase="webapps/aaa"。配置如下：

<Host name="localhost"  appBase=""
            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" />

       <Context path="/" docBase="webapps/aaa" reloadable="false"/>

      </Host>