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javax.naming.NamingException：无法创建资源实例

分类: 技术问答 • 2022-08-07 10:47:22
问题描述：

似乎有关于这个问题的几个主题，但还找不到答案。林相当新的JSF和想用创建PostgreSQL的连接池：javax.naming.NamingException：无法创建资源实例

  • JSF 2.2.9
  • 的Tomcat 8.0.27

但是tomcat的总是给我一个HTTP状态500 - 错误实例化servlet类错误（堆栈跟踪在帖子结尾） 你能帮我吗？

我的文件：

的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>

的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>

（DB变更地址，用户名和PW）

TestServlet.java

package com.postgres; 

import java.io.IOException; 
import java.io.PrintWriter; 
import java.sql.Connection; 
import java.sql.ResultSet; 
import java.sql.Statement; 

import javax.annotation.Resource; 
import javax.servlet.ServletException; 
import javax.servlet.annotation.WebServlet; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import javax.sql.DataSource; 

@WebServlet("/TestServlet") 
public class TestServlet extends HttpServlet { 

    /** 
    * 
    */ 
    private static final long serialVersionUID = -7524281845027879453L; 
    @Resource(name = "jdbc/einfuehrungsaufgabe") 
    private DataSource dataSource; 


    protected void doGet(HttpServletRequest request, 
      HttpServletResponse response) throws ServletException, IOException { 

     PrintWriter out = response.getWriter(); 
     response.setContentType("text/plain"); 

     Connection myConn = null; 
     Statement myStmt = null; 
     ResultSet myRs = null; 

     //some code 
    } 

}

堆栈跟踪

javax.servlet.ServletException: Error instantiating servlet class com.postgres.TestServlet 
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) 
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) 
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) 
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) 
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) 
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) 
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) 
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    java.lang.Thread.run(Thread.java:745) 
root cause 

javax.naming.NamingException: Cannot create resource instance 
    org.apache.naming.factory.FactoryBase.getObjectInstance(FactoryBase.java:96) 
    javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:321) 
    org.apache.naming.NamingContext.lookup(NamingContext.java:841) 
    org.apache.naming.NamingContext.lookup(NamingContext.java:152) 
    org.apache.naming.NamingContext.lookup(NamingContext.java:829) 
    org.apache.naming.NamingContext.lookup(NamingContext.java:166) 
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) 
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) 
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) 
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) 
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) 
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) 
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) 
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    java.lang.Thread.run(Thread.java:745)

WEB-INF/lib中

  • 的javax.servlet-API-3.1.0.jar
  • 的PostgreSQL-9.4-1203.jdbc4.jar

答

多么愚蠢的错误！ 这只是在context.xml文件一个错字： 

type="javax.sql.Datasource"

改为： 

type="javax.sql.DataSource"

现在工作得很好:)

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