用eclipse打开WEB项目出现数据库连接问题，该怎么解决

qq_31404351 2017-12-16 12:32:46

错误原因：
HTTP Status 500 – Internal Server Error

Type Exception Report

Message An exception occurred processing [topOne.jsp] at line [7]

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception
org.apache.jasper.JasperException: An exception occurred processing [topOne.jsp] at line [7]

4: <%@page import="com.domain.LinkForm" %>
5: <jsp:useBean id="dao" scope="page" class="com.dao.LinkDao"/>
6: <meta http-equiv="Content-Type" content="text/html; charset=gb2312">
7: <% List list =dao.selectLink();%>
8: <link href="css/css.css" rel="stylesheet" type="text/css">
9: <table width="757" height="106" border="0" cellpadding="0" cellspacing="0" background="image/banner.jpg">
10: <tr>

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:593)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:467)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Root Cause
org.apache.jasper.JasperException: An exception occurred processing [topOne.jsp] at line [7]

4: <%@page import="com.domain.LinkForm" %>
5: <jsp:useBean id="dao" scope="page" class="com.dao.LinkDao"/>
6: <meta http-equiv="Content-Type" content="text/html; charset=gb2312">
7: <% List list =dao.selectLink();%>
8: <link href="css/css.css" rel="stylesheet" type="text/css">
9: <table width="757" height="106" border="0" cellpadding="0" cellspacing="0" background="image/banner.jpg">
10: <tr>

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:593)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:482)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:895)
org.apache.jsp.index_jsp._jspService(index_jsp.java:121)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:444)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Root Cause
java.lang.NullPointerException
com.dao.LinkDao.selectLink(LinkDao.java:123)
org.apache.jsp.topOne_jsp._jspService(topOne_jsp.java:127)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:444)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:895)
org.apache.jsp.index_jsp._jspService(index_jsp.java:121)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:444)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Note The full stack trace of the root cause is available in the server logs.
LinkDao.java代码
@SuppressWarnings("rawtypes")
public List selectLink()
{
List list = new ArrayList();
LinkForm link =null;
try
{
ps = connection.prepareStatement("select * from tb_link order by id DESC"); //（这行是123行）
for(ResultSet rs = ps.executeQuery(); rs.next(); list.add(link))
{
link = new LinkForm();
link.setId(Integer.valueOf(rs.getString(1)));
link.setLinkName(rs.getString(2));
link.setLinkAddress(rs.getString(3));
link.setLinkPicture(rs.getString(4));
link.setLinkTime(rs.getString(5));
}

}
catch(SQLException ex) { }
return list;
}

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