UC知道以下代码错在哪儿，老出现java.lang.NullPointerException？
来源：百度知道 编辑：UC知道 时间：2024/06/21 19:53:03
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<%@ page import="ddd.connDB"%>
<%@ page import="ddd.MemberDaoImpl" %>
<jsp:useBean id="member" scope="request" class="ddd.member">
<jsp:setProperty name="member" property="*"/>
</jsp:useBean>
<html>
<head>
<title>用户注册成功!</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>
<body>
<%
connDB conn=new connDB();
request.setCharacterEncoding("gb2312");
String username=member.getUsername();
ResultSet rs=conn.executeQuery("select * from user where userName='"+username+"'");
if (rs.next()){
out.println("<scrip
<%@ page import="ddd.connDB"%>
<%@ page import="ddd.MemberDaoImpl" %>
<jsp:useBean id="member" scope="request" class="ddd.member">
<jsp:setProperty name="member" property="*"/>
</jsp:useBean>
<html>
<head>
<title>用户注册成功!</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>
<body>
<%
connDB conn=new connDB();
request.setCharacterEncoding("gb2312");
String username=member.getUsername();
ResultSet rs=conn.executeQuery("select * from user where userName='"+username+"'");
if (rs.next()){
out.println("<scrip
java.lang.NullPointerException
这个异常代表有空的引用，检查下你的变量是否在null的情况下被调用。
估计就是这一句吧
<jsp:useBean id="member" scope="request" class="ddd.member">
<jsp:setProperty name="member" property="*"/>
</jsp:useBean>
这一段的效果是将页面中一些属性的值赋给bean,但你的这些属性都没有值吧，就进行赋值，就会出现nullpointerException