Question

jdbc连接数据库问题

type Exception report
message An exception occurred processing JSP page /testconnection.jsp at line 30
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: An exception occurred processing JSP page /testconnection.jsp at line 3027: else28: out.println("连接数据库成功"); 29: try {30: conn.close();31: } catch (SQLException e) {32: out.println("关闭数据库连接时出现SQL异常");33: } Stacktrace: org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

root cause
java.lang.NullPointerException org.apache.jsp.testconnection_jsp._jspService(testconnection_jsp.java:92) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.30 logs.

以下是代码

Answer 1

空指针异常。报错位置也很明显告诉你了，在30: conn.close(); 这是因为你在最上方创建该对象的时候，是直接Connection conn = null;你需要修改你的代码。

Answer 2

检查mysql服务是否启动？用户名的密码是否正确？