JSP中出现java.lang.NullPointerException怎么解决

王朝知道·作者佚名  2009-08-01
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問題描述:

package login;

import java.sql.*;

//import com.mircosoft.jdbc.sqlserver.SQLServerDriver;

public class UserRegist

{

private UserInfo userInfo;

private Connection con;

public UserRegist()

{

String CLASSFORNAME = "com.mircosoft.jdbc.sqlserver.SQLServerDriver";

String SERVANDDB = "jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=jspbook";

String USER = "sa";

String PWD = "123";

try

{

Class.forName(CLASSFORNAME).newInstance();

con = DriverManager.getConnection(SERVANDDB,USER,PWD);

}

catch(Exception e)

{

e.printStackTrace();

}

}

//设置待注册的用户信息

public void setUserInfo(UserInfo userInfo)

{

this.userInfo = userInfo;

}

//进行注册

public void regist() throws Exception

{

String reg = "insert into user_Info values(?,?,?,?,?,?,?,?,?,?,?)";

try

{

PreparedStatement pstmt = con.prepareStatement(reg);

//创建一个预处理语句,然后设置它们的参数

pstmt.setString(1,userInfo.getUserId());

pstmt.setString(2,userInfo.getName());

pstmt.setString(3,userInfo.getPhone());

pstmt.setString(4,userInfo.getCity());

pstmt.setString(5,userInfo.getEmail());

pstmt.setString(6,userInfo.getQuestion());

pstmt.setString(7,userInfo.getAnswer());

pstmt.setDate(8,new java.sql.Date(new java.util.Date().getTime()));

pstmt.setString(9,userInfo.getPassWord());

pstmt.setInt(10,1);

pstmt.setInt(11,0);

//执行操作

pstmt.executeUpdate();

}

catch(Exception e)

{

e.printStackTrace();

throw e;

}

}

}

错误如下:

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:510)

org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)

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 cause

java.lang.NullPointerException

login.UserRegist.regist(UserRegist.java:41)

org.apache.jsp.newuser_jsp._jspService(newuser_jsp.java:72)

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:332)

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/5.5.17 logs.

參考答案:

con没有获得连接,你在con = DriverManager.getConnection(SERVANDDB,USER,PWD);

这段下面输出con看看是否是null

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