在debug里出错的地方已经注释标明，在这里谢谢大家了，在线等，很急的，有什么可以问，马上回！谢谢指导！
package yang;
import java.sql.*;
public class JDBConnection {
private final String dbDrive="com.microsoft.sqlserver.jdbc.SQLServerDriver";
private final String url="jdbc:sqlserver://localhost:1433;DatabastName=yang";
private final String userName="sa";
private final String password="*******";
private Connection con=null;
public JDBConnection(){ //构造方法加载驱动
try {
Class.forName(dbDrive).newInstance();
} catch (Exception ex) {
System.out.println("数据库驱动加载失败："+ex);
}
}
public boolean creatConnection(){ //数据库连接
try {
con = DriverManager.getConnection(url,userName,password);
con.setAutoCommit(true);
} catch (SQLException e) {
System.out.println("数据库连接失败:"+e);
}
return true;
}
public boolean executeUpdate(String sql){ //对数据表增，删，改
if(con==null){
creatConnection();
}
try {
Statement stmt = con.createStatement();
int iCount = stmt.executeUpdate(sql);
System.out.println("操作成功，所影响的记录数为"+ String.valueOf(iCount));
return true;
} catch (SQLException e) {
return false;
}
}
public ResultSet executeQuery(String sql){ //对数据表查询
ResultSet rs=null; //在debug里是这里出错
try {
if(con==null){
creatConnection();
}
Statement stmt = con.createStatement();
rs = stmt.executeQuery(sql);
return null;
} catch (SQLException e) {
//e.printStackTrace();
}
return rs ;
}
public void closeConnection(){ //关闭数据库连接
if(con==null){
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
下面是jsp代码
<%@page import="java.sql.ResultSet"%>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@page import="java.sql.*"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<jsp:directive.page import="yang.JDBConnection"/>
<%
JDBConnection connection = new JDBConnection();
String sql = "use yang select*from users";
ResultSet rs = connection.executeQuery(sql);
%>
<body>
<table>
<!-- 以下代码显示用户信息 -->
<tr>
<td>id号</td><td>姓名</td>
<td>性别</td><td>生日</td>
<td>籍贯</td><td>电话</td>
</tr>
<%
try{
while(rs.next()){
%>
<tr>
<td><%=rs.getInt(1)%></td><td><%=rs.getString(2)%></td>
<td><%=rs.getString(3)%></td><td><%=rs.getString(4)%></td>
<td><%=rs.getString(5)%></td><td><%=rs.getString(6)%></td>
</tr>
<%
}}catch(Exception e){
e.printStackTrace();
}
finally{
connection.closeConnection();
}
%>
</table>
<form action="addUsers.jsp" id="form1" name="form1" method = "post">
<table>
<tr>
<td>姓名：</td>
<td><input name="name" type="text" id="name" size="20"/></td>
<td>生日：</td>
<td><input name="birthday" type="text" id="birthday" size="11"/></td>
</tr>
<tr>
<td>性别：</td>
<td><input name="sex" type="radio" value="男" checked="checked"/>
男<input name="sex" type="radio" value="女"/>女</td>
<td>电话：</td>
<td><input name="tel" type="text" id="tel" size="11"/></td>
</tr>
<tr>
<td>籍贯：</td>
<td><input name="address" type="text" id="address"/></td>
<td> </td>
</tr>
</table>
<input type="submit" name="Submit" value="增加"\>
<input type="reset" name="Submit2" value="重置"/>
</form>
</body>
</html>
这个是异常信息
java.lang.NullPointerException
at org.apache.jsp.index_jsp._jspService(index_jsp.java:114)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:744)
