好心人帮帮忙解决一下数据库连接的问题!急!急!
请高手们帮我看看这个问题，搞了好几次都出现错误（已经加载了sqlserver的3个驱动文件）,源程序和出现的错误提示如下:
package shop;
import java.sql.*;
public class DBConnectBean {
public static Connection getSqlserverConn()
{
Connection conn=null;
String url= "com.microsoft.jdbc.sqlserver.SQLServerDriver ";
String sqldriver= "jdbc:microsoft:sqlserver://localhost:1433;DataBaseName=jspdev ";
try {
Class.forName(url);
conn=DriverManager.getConnection(sqldriver, "sa ", " ");
conn.setCatalog( "jspdev ");
}
catch (Exception ex) {
ex.printStackTrace();
}
return conn;
}
}
---------------------------------------------------
<%@ page contentType= "text/html; charset=GBK " import= "java.sql.* "%>
<html>
<head>
<title>
logincheck.jsp
</title>
</head>
<body bgcolor= "#ffffff ">
<jsp:useBean id= "dbconn " class= "shop.DBConnectBean " scope= "page "/>
<%
//获得请求参数
String name=request.getParameter( "username ");
String password=request.getParameter( "userpassword ");
//连接数据库
dbconn.getSqlserverConn();
String usersql= "select * from users where name= ' "+name+ " 'and password= ' "+password+ " ' ";
Connection con=null;
Statement stmt=con.createStatement();
ResultSet result=stmt.executeQuery(usersql);
if(result.next())
{
%>
欢迎你， <%=name%>
<%}%>
</body>
</html>
------------------------------------------------
java.lang.NullPointerException
java.lang.NullPointerException
at org.apache.jsp.logincheck$jsp._jspService(logincheck$jsp.java:96)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:201)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:381)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:473)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2347)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1027)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1125)
at java.lang.Thread.run(Thread.java:536)
[解决办法]
Connection con=null;
Statement stmt=con.createStatement();
con是null,你使用他就会报空指针异常.
应该把Connection con=null;去掉
在dbconn.getSqlserverConn();的前面加上:
Connection con = dbconn.getSqlserverConn();
