java - 无法获取连接，DataSource 无效 : "java. sql.SQLException: 无法创建 PoolableConnectionFactory(通信链接失败

Question

当我尝试测试我编写的 servlet 时，我不断收到此错误。当我将相同的 servlet 部署到生产环境时，我得到了实际的应用程序。我对 mysql 的登录数据进行了两次和三次检查。我为我的工作站添加了端口异常(exception)，并验证了服务器端口正在监听我。我正在尝试连接到生产数据库。所有连接字符串都是相同的，我已经配置了 context.xml 以查看具有实际生产系统的准确拼写的资源。我还验证了 jar 存在。我不确定这里的问题是什么。

Mar 23, 2015 6:05:13 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/JSPListRecords] threw exception [javax.servlet.ServletException: javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid: "java.sql.SQLException: Cannot create PoolableConnectionFactory (Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.)"] with root cause
javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid: "java.sql.SQLException: Cannot create PoolableConnectionFactory (Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.)"
    at org.apache.taglibs.standard.tag.common.sql.QueryTagSupport.getConnection(QueryTagSupport.java:318)
    at org.apache.taglibs.standard.tag.common.sql.QueryTagSupport.doStartTag(QueryTagSupport.java:201)
    at org.apache.jsp.ListUsers_jsp._jspx_meth_sql_005fquery_005f0(ListUsers_jsp.java:172)
    at org.apache.jsp.ListUsers_jsp._jspService(ListUsers_jsp.java:118)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:431)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659)
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

Answer 1

发现因为服务器是 Amazon 的一个 rds 实例，数据库没有设置为公共(public)访问。使用适当的设置恢复了快照，我们开始营业了。