NullPointerException для getDataSource (). GetConnection ()

Question

У меня есть веб-приложение jsp + servlets, развернутое на сервере Tomcat.Я использую пул соединений, как показано ниже

public class DBConnection {

    public static DataSource datasource = null;

    public static DataSource getDataSource() {
        return datasource;
    }

    static {
        initializeDataSource();
    }

    public static void initializeDataSource() {
        try {
            InitialContext initialContext;
            initialContext = new InitialContext();
            Context context = (Context) initialContext.lookup("java:comp/env");
            datasource = (DataSource) context.lookup("dbconn");
        } catch (NamingException ex) {
            Logger.getLogger(DBConnection.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}

Чтобы получить соединение:

Connection connection = DBConnection.getDataSource().getConnection();

context.xml

<Context path="/adminapp">
  <Resource auth="Container" defaultAutoCommit="false" driverClassName="com.mysql.jdbc.Driver" logAbandoned="true" maxIdle="5" maxTotal="150" maxWaitMillis="-1" minEvictableIdleTimeMillis="60000" name="dbconn" password="" removeAbandonedOnBorrow="true" removeAbandonedOnMaintenance="true" removeAbandonedTimeout="300" timeBetweenEvictionRunsMillis="180000" type="javax.sql.DataSource" url="jdbc:mysql://localhost:3306/data?useEncoding=true&amp;characterEncoding=UTF-8" username="root"/>
</Context> 

Я развернул это приложение в Tomcatработает отлично.Я могу получить доступ к приложению, используя url https://example.com:8443/adminapp/

Теперь я переключился на виртуальный хост в Tomcat, изменив XML-сервер tomcat, как показано ниже

    <!-- 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>

  <Host name="adminapp.example.com"  appBase="webapps"
        unpackWARs="true" autoDeploy="false" deployOnStartup="false">



    <!-- 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="knestlms_admin"/>
  </Host>

После виртуального хоста яполучить эту ошибку в журнале:

 javax.naming.NamingException: Cannot create resource instance
    at org.apache.naming.factory.FactoryBase.getObjectInstance(FactoryBase.java:96)
    at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:321)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:839)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:173)
    at Utils.DBConnection.initializeDataSource(DBConnection.java:36)
    at Utils.DBConnection.<clinit>(DBConnection.java:28)
    at org.apache.jsp.login_jsp._jspService(login_jsp.java:221)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:457)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176)
    at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145)
    at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92)
    at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:394)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:728)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:470)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:395)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:316)
    at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:213)
    at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:171)
    at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145)
    at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92)
    at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:394)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:610)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)