HTTP Status 500 - 我是一个初学者Tomcat JDK开发，出现如下错误，为什么如何解决呢谢谢

显示全部楼层 · 2011-2-24 03:20:44

HTTP Status 500 -
--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
org.apache.jsp.index_jsp._jspService(index_jsp.java:64)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

root cause

java.lang.NullPointerException
com.dao.Dbssort.Select(Dbssort.java:111)
com.dao.DbBasetableFactory.ListSsort(DbBasetableFactory.java:143)
com.BasetableFactoryProxy.ListSsort(BasetableFactoryProxy.java:105)
org.apache.jsp.top_jsp._jspService(top_jsp.java:94)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
org.apache.jsp.index_jsp._jspService(index_jsp.java:64)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.16 logs.

千问 · 2011-2-24 03:20:44

<pre id=\\\"best-answer-content\\\" class=\\\"reply-text mb10\\\">先看看你连接打开了吗，
再看看你sql语句是否对，在数据库界面工具执行下看看能执行吗？
还不行把代码贴过来看看。

<h4 class=\\\"ask\\\">追问

<pre class=\\\"replyask-text\\\" id=\\\"content-156640\\\">{Collection coll = new ArrayList(); Connection con = null; ResultSet rs = null; PreparedStatement ps = null; try { con = Database.getConnection();
ps = con.prepareStatement(FinalConstants.SELECT_SSORT sql); rs = ps.executeQuery();
while (rs.next()) {

Ssort link = new Ssort();

link.setSid(rs.getInt(\\\"sid\\\"));

千问 · 2011-2-24 03:20:44

<pre class=\\\"replyask-text\\\" id=\\\"content-160139\\\">你这段代码没问题，
这个类是Dbssort.java吗？
“FinalConstants.SELECT_SSORT sql” 看看有没有问题。

千问 · 2011-2-24 03:20:44

<pre class=\\\"replyask-text\\\" id=\\\"content-170867\\\">用几个例子试了一下，好像涉及到数据库的都不行，数据库连接除了问题，这个怎么连接怎么检查呢？非常感谢

千问 · 2011-2-24 03:20:44

<pre class=\\\"replyask-text\\\" id=\\\"content-191733\\\">Database.getConnection();
这方法是连接数据库；看看那有问题。

千问 · 2011-2-24 03:20:44

<pre class=\\\"replyask-text\\\" id=\\\"content-94281\\\">这是从109行到115行，帮忙看一下非常谢谢，111行是什么错了呀
try {

con = Database.getConnection();

ps = con.prepareStatement(FinalConstants.SELECT_SSORT sql);

rs = ps.executeQuery();

while (rs.next()) {

Ssort link = new Ssort();

link.setSid(rs.getInt(\\\"sid\\\"));

千问 · 2011-2-24 03:20:44

<pre class=\\\"replyask-text\\\" id=\\\"content-115298\\\">debug一下，看看是哪个对象为空就好了
另外为什么每次都Ssort link = new Ssort(); 进行初始化呢？是不是应该在循环体之外进行link 对象初始化

写程序，调试很重要，一定要掌握基本的调试技巧

HTTP Status 500 - 我是一个初学者Tomcat JDK开发，出现如下错误，为什么 如何解决呢 谢谢

HTTP Status 500 - 我是一个初学者Tomcat JDK开发，出现如下错误，为什么如何解决呢谢谢