[求助] 帮忙看看这个错误大概是什么意思？？_Java Web开发

[求助] 帮忙看看这个错误大概是什么意思？？

偶是新手，刚看了点JSP的书
在测试数据库的时候出了这么一个错误信息，我实在看不懂错误是什么意思！！

有经验的朋友帮忙看看！！

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: Exception in JSP: /dbprogram.jsp:52

49: out.println("恭喜，表连接创建成功！");
50: %>
51:
52: <%
53: ResultSet RS= Stmt.executeQuery("SELECT * FROM EMPLOYEE WHERE eage<25"); /*连接到数据库中的表EMPLOYEE上*/
54: String tt; /**号表示选择表中所有的列*/
55: String link; /*若选择其中的某几列可以将*号换成列标号*/

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:467)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:389)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

root cause

java.lang.NullPointerException
org.apache.jsp.dbprogram_jsp._jspService(dbprogram_jsp.java:104)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:328)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.23 logs.

--------------------------------------------------------------------------------

Apache Tomcat/5.5.23

搜索更多相关主题的帖子: 数据库 Exception The JSP

----------------解决方案--------------------------------------------------------
没代码，看不懂！
----------------解决方案--------------------------------------------------------

好像是有空指针异常，看看连接有没有问题！！

----------------解决方案--------------------------------------------------------
不是好象,就是!!!不过没代码哪能找到错误!
----------------解决方案--------------------------------------------------------

谢谢各位！！
我没发现有空指针异常在程序哪个地方？？
帮忙看一下
下面是代码：

<%@ page contentType="text/html; charset=gb2312" %>
<%@ page info="database handler"%>
<%@ page import="java.io.*"%>
<%@ page import="java.util.*"%>
<%@ page import="java.sql.*"%>
<%@ page import="javax.servlet.*"%>
<%@ page import="javax.servlet.http.*"%>

<html>
<head>
<title>数据库连接实验</title>
</head>
<body>
<%
String sDBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
String sConnStr = "jdbc:odbc:try";//“try”的意思就是与刚才设置的数据源名对应;
Connection Con = null;
Statement Stmt = null;
try
{
try /*加载驱动程序*/
{
Class.forName(sDBDriver);
}
catch(java.lang.ClassNotFoundException e)
{
out.print("Connect to Database error: " + e.getMessage());
}
try /*建立连接*/
{
Con = DriverManager.getConnection(sConnStr,"sa","");
}
catch(SQLException e)
{
out.print(e.toString());
}

Stmt = Con.createStatement(); /*创建JDBC声明*/
String query="CREATE TABLE GUEST" + /*在数据库中创建新的表*/
"(NUM VARCHAR(32),"+
"USERNAME TEXT,"+
"CONTENT TEXT,"+
"PASSWORD INTEGER,"+
"TOTAL INTEGER,"+
"REALNAME TEXT)";
Stmt.executeUpdate(query); /*更新数据库*/
}
catch (Exception e) {}
out.println("恭喜，表连接创建成功！");
%>

<%
ResultSet RS= Stmt.executeQuery("SELECT * FROM EMPLOYEE WHERE eage<25"); /*连接到数据库中的表EMPLOYEE上*/
String tt; /**号表示选择表中所有的列*/
String link; /*若选择其中的某几列可以将*号换成列标号*/
String makeStr; /*WHERE语句表示条件选择*/
out.print("<table border=2 style=color:blue >");
while (RS.next()) {
out.print("<tr><td>");
tt = RS.getString("ename"); /*查询表中NUM字段的内容，字段内容可能使数组，默认列输出*/
out.print(tt);
out.print("</td><td>");
tt = RS.getString("esex");
out.print(tt);
out.print("</td><td>");
tt = RS.getString("eage");
out.print(tt);
out.print("</td><td>");
tt=RS.getString("egrade");
out.print(tt);
out.print("</td><td>");
}
out.print("</table>");
RS.close();
out.println("数据查询成功！");
%>

<% /*在数据库中添加数据*/
String sql="INSERT INTO EMPLOYEE VALUES ('5','aaa','m',54,'hehe')";
Stmt.executeUpdate(sql);
out.println("添加数据成功!");
%>
</body>
</html>

----------------解决方案--------------------------------------------------------
Exception in JSP: /dbprogram.jsp:52

这个代码的第52行

你自己看看是什么
----------------解决方案--------------------------------------------------------

代码52行是红色的部分，我还是没看懂是什么问题

<%@ page contentType="text/html; charset=gb2312" %>
<%@ page info="database handler"%>
<%@ page import="java.io.*"%>
<%@ page import="java.util.*"%>
<%@ page import="java.sql.*"%>
<%@ page import="javax.servlet.*"%>
<%@ page import="javax.servlet.http.*"%>

<html>
<head>
<title>数据库连接实验</title>
</head>
<body>
<%
String sDBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
String sConnStr = "jdbc:odbc:try";//“try”的意思就是与刚才设置的数据源名对应;
Connection Con = null;
Statement Stmt = null;
try
{
try /*加载驱动程序*/
{
Class.forName(sDBDriver);
}
catch(java.lang.ClassNotFoundException e)
{
out.print("Connect to Database error: " + e.getMessage());
}
try /*建立连接*/
{
Con = DriverManager.getConnection(sConnStr,"sa","");
}
catch(SQLException e)
{
out.print(e.toString());
}

<% /*在数据库中添加数据*/
String sql="INSERT INTO EMPLOYEE VALUES ('5','aaa','m',54,'hehe')";
Stmt.executeUpdate(sql);
out.println("添加数据成功!");
%>
</body>
</html>

----------------解决方案--------------------------------------------------------
ResultSet RS= Stmt.executeQuery("SELECT * FROM EMPLOYEE WHERE eage<25");
先确保你的stmt对象是否已存在，否则他是个NULL值。你先看看你上面的Stmt = Con.createStatement()是否建立
----------------解决方案--------------------------------------------------------

谢谢！
真的有点烦！！
我把数据库的设置改了一下！配置数据源的时候采用的是Windows身份认证了
Con = DriverManager.getConnection(sConnStr,"sa",""); 也改为了
Con = DriverManager.getConnection(sConnStr);

改后的代码如下：

<%@ page contentType="text/html; charset=gb2312" %>
<%@ page info="database handler"%>
<%@ page import="java.io.*"%>
<%@ page import="java.util.*"%>
<%@ page import="java.sql.*"%>
<%@ page import="javax.servlet.*"%>
<%@ page import="javax.servlet.http.*"%>

<html>
<head>
<title>数据库连接实验</title>
</head>
<body>
<%
String sDBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
String sConnStr = "jdbc:odbc:try";//“try”的意思就是与刚才设置的数据源名对应;
Connection Con = null;
Statement Stmt = null;
try
{
try /*加载驱动程序*/
{
Class.forName(sDBDriver);
}
catch(java.lang.ClassNotFoundException e)
{
out.print("Connect to Database error: " + e.getMessage());
}
try /*建立连接*/
{
Con = DriverManager.getConnection(sConnStr); ／*代码修改的地方*/
}
catch(SQLException e)
{
out.print(e.toString());
}

<% /*在数据库中添加数据*/
String sql="INSERT INTO EMPLOYEE VALUES ('5','aaa','m',54,'hehe')";
Stmt.executeUpdate(sql);
out.println("添加数据成功!");
%>
</body>
</html>

现在出的错误变成这样的了：

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
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:476)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:389)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:315)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

root cause

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.23 logs.

--------------------------------------------------------------------------------

Apache Tomcat/5.5.23

劳驾帮忙看看这错误又是什么意思呢？？？　　还是空指针？？
如果是空指针，那又是哪行代码了呢？？

----------------解决方案--------------------------------------------------------
还是空指针异常，其实空指针异常是最好排除的，无非就是保证你所用到的对象都不是null就可以了

你可以在你每生成一个对象的时候，用System.out.println来输出一下，看看它是不是 null的就知道在那里哪个对象被赋了null了
----------------解决方案--------------------------------------------------------