向MySQL中插入数据库出现错误?
JSP中的代码如下:
<jsp:useBean id="connBean" scope="page" class="beans.ConnDB" />
<%
connBean.executeUpdate("insert into tbl_User(UserName) values('姓名')");
%>
javaBean中的代码如下:
public int executeUpdate(String sql){
int result=0;
try{
conn=java.sql.DriverManager.getConnection(url,user,password);
result=stmt.executeUpdate(sql);
}
catch (SQLException e) {
result=0;
}
return result;
}
运行后出现如下错误:
java.lang.NullPointerException
beans.ConnDB.executeUpdate(ConnDB.java:51)
org.apache.jsp.Insert_jsp._jspService(org.apache.jsp.Insert_jsp:76)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:99)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:325)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
请问这是怎么回事啊