小弟请教帮助
//index.jsp<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*,testdb.Datebase" errorPage="" %>
<html>
<head>
<title>测试数据库</title>
</head>
<body bgcolor="#FFFFFF">
<%
Datebase db = new Datebase();
String sql = "select * from bookTab";
ResultSet rs2 = db.getResult(sql);
while(rs2.next()){%>
<br>第一个字段内容:<%=rs2.getString(1)%>
第二个字段内容:<%=rs2.getString(2)%>
<%}%><br>
<%out.print("非常好,成功了"); %>
<%rs2.close();
db.closeConnection();
%>
这里写你的内容</body>
</html>====================================================================================
//Datebase.java
package testdb;import java.sql.*;public class Datebase {
Connection con;
ResultSet rs;
Statement stmt;
public Datebase(){
// 定义连接类型及连接数据库 ACCESS
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String strurl="jdbc:odbc:driver={Microsoft Access Driver (*.mdb)};DBQ=c:\bookbase.mdb";
con=DriverManager.getConnection(strurl) ;
stmt=con.createStatement();
}// 异常抛出
catch(Exception e)
{ System.out.println(e); }
}
// 定义数据库执行返回值 RS;
public ResultSet getResult(String strSQL)
{
try{
rs=stmt.executeQuery(strSQL);
return rs;
}
catch(SQLException sqle)
{
System.out.println(sqle.toString());
return null;
}
catch(NullPointerException e)
{
System.out.println(e.toString());
return null;
}
}
// 定义数据库修改保存类
public boolean updateSql(String strSQL)
{
try{
stmt.executeUpdate(strSQL);
con.commit();
return true;
}
catch(SQLException sqle)
{
System.out.println(sqle.toString());
return false;
}
}//定义关闭数据库类
public void closeConnection()
{
try
{
stmt.close();
con.close();
}
catch(SQLException sqle)
{
System.out.println(sqle.toString());
}
}
}
=======================================================================================
tomcat里调试出错信息如下:
HTTP Status 500 -type Exception reportmessagedescription The server encountered an internal error () that prevented it from fulfilling this request.exceptionorg.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)root causejava.lang.NullPointerException
org.apache.jsp.index_jsp._jspService(org.apache.jsp.index_jsp:54)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)note The full stack trace of the root cause is available in the Apache Tomcat/5.5.12 logs.
小弟哪里怎么写错了?请求帮助
//index.jsp<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*,testdb.Datebase" errorPage="" %>
<html>
<head>
<title>测试数据库</title>
</head>
<body bgcolor="#FFFFFF">
<%
Datebase db = new Datebase();
String sql = "select * from bookTab";
ResultSet rs2 = db.getResult(sql);
while(rs2.next()){%>
<br>第一个字段内容:<%=rs2.getString(1)%>
第二个字段内容:<%=rs2.getString(2)%>
<%}%><br>
<%out.print("非常好,成功了"); %>
<%rs2.close();
db.closeConnection();
%>
这里写你的内容</body>
</html>====================================================================================
//Datebase.java
package testdb;import java.sql.*;public class Datebase {
Connection con;
ResultSet rs;
Statement stmt;
public Datebase(){
// 定义连接类型及连接数据库 ACCESS
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String strurl="jdbc:odbc:driver={Microsoft Access Driver (*.mdb)};DBQ=c:\bookbase.mdb";
con=DriverManager.getConnection(strurl) ;
stmt=con.createStatement();
}// 异常抛出
catch(Exception e)
{ System.out.println(e); }
}
// 定义数据库执行返回值 RS;
public ResultSet getResult(String strSQL)
{
try{
rs=stmt.executeQuery(strSQL);
return rs;
}
catch(SQLException sqle)
{
System.out.println(sqle.toString());
return null;
}
catch(NullPointerException e)
{
System.out.println(e.toString());
return null;
}
}
// 定义数据库修改保存类
public boolean updateSql(String strSQL)
{
try{
stmt.executeUpdate(strSQL);
con.commit();
return true;
}
catch(SQLException sqle)
{
System.out.println(sqle.toString());
return false;
}
}//定义关闭数据库类
public void closeConnection()
{
try
{
stmt.close();
con.close();
}
catch(SQLException sqle)
{
System.out.println(sqle.toString());
}
}
}
=======================================================================================
tomcat里调试出错信息如下:
HTTP Status 500 -type Exception reportmessagedescription The server encountered an internal error () that prevented it from fulfilling this request.exceptionorg.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)root causejava.lang.NullPointerException
org.apache.jsp.index_jsp._jspService(org.apache.jsp.index_jsp:54)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)note The full stack trace of the root cause is available in the Apache Tomcat/5.5.12 logs.
小弟哪里怎么写错了?请求帮助
java.lang.NullPointerException
出现这个错误一般是初始化对象的错误,你在找找看是不是这方面的问题!