public static String getJdbcName() {
    if (jdbcName == null) {
        ConfigLoader oConfigLoader = ConfigLoader.getInstance();
        setJdbcName(oConfigLoader.getProperty("general.jndi"));
        logger.info("jdbcName:"+jdbcName);
    }
    return jdbcName;
}

java:comp/env/jdbc/settmdr

public  DataSource getDataSource(  ) throws  Exception {
    if (ds == null) {
        try{
            Context iniCtx = new InitialContext();
            iniCtx.lookup("java:comp/env");
            getJdbcName();
            ds = ( DataSource )iniCtx.lookup(jdbcName);
            logger.info(" Se obtiene el dataSource ...");
        }catch( NamingException e ){
            e.printStackTrace();
        }
    }
    return ds;
}

<GlobalNamingResources>
    <!-- Editable user database that can also be used by
         UserDatabaseRealm to authenticate users
    -->
    <Resource auth="Container" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" name="UserDatabase" pathname="conf/tomcat-users.xml" type="org.apache.catalina.UserDatabase"/>

  <Resource
                global="jdbc/Tomcat"
                name="jdbc/Tomcat"
                auth="Container"
                type="javax.sql.DataSource"
                factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
                initialSize="10"
                minIdle="5"
                maxIdle="25"
                maxWait="15000"
                maxActive="350"
                testWhileIdle="true"
                testOnReturn="false"
                validationQuery="SELECT 1 FROM DUAL"
                validationInterval="30000"
                timeBetweenEvictionRunsMillis="30000"
                minEvictableIdleTimeMillis="30000"
              password="pgt_mex"
                username="pgt_mex"
                driverClassName="oracle.jdbc.driver.OracleDriver"
                url="jdbc:oracle:thin:@ 180.181.37.37:1651:mexmdrt
"
        />


  </GlobalNamingResources>

<ResourceLink global="jdbc/Tomcat" name="jdbc/Tomcat" type="javax.sql.DataSource"/>

<context-param>
        <param-name>jdbcPool</param-name>
       <param-value>jdbc/Tomcat</param-value>
</context-param>

<resource-ref>
        <description>Oracle Datasource eRiskMan</description>
       <res-ref-name>jdbc/Tomcat</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
        <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>