关于这个问题似乎有几个话题，但是找不到答案。我对JSF不太熟悉，并且想使用以下方法创建一个postgresql连接池：

• JSF 2.2.9
• Tomcat 8.0.27

但是tomcat总是给我一个HTTP Status 500-实例化servlet类错误的错误（帖子末尾的堆栈跟踪）您能帮我吗？

我的文件：

web.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
      <display-name>Postgresql</display-name>
      <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
      </servlet>
      <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
      </servlet-mapping>
      <context-param>
        <description>State saving method: 'client' or 'server' (=default). See JSF Specification 2.5.2</description>
        <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
        <param-value>client</param-value>
      </context-param>
      <context-param>
        <param-name>javax.servlet.jsp.jstl.fmt.localizationContext</param-name>
        <param-value>resources.application</param-value>
      </context-param>
      <listener>
        <listener-class>com.sun.faces.config.ConfigureListener</listener-class>
      </listener>
      <resource-ref>
        <description>Postgres Test</description>
        <res-ref-name>jdbc/einfuehrungsaufgabe</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
      </resource-ref>
    </web-app>

context.xml

<context>

    <Resource name="jdbc/einfuehrungsaufgabe" auth="Container"
        type="javax.sql.Datasource" maxActive="20" maxIdle="5" maxWait="10000"
        username="foo" password="foo" driverClassName="org.postgresql.Driver"
        url="jdbc:postgresql://foo.de/foo">
    </Resource>

</context> …