我运行时，报这个错误？请大家告诉我，怎么处理？先谢谢！
java.lang.NullPointerException
cn.com.jobedu.blog.UserServlet.login(UserServlet.java:55)
cn.com.jobedu.blog.UserServlet.doPost(UserServlet.java:31)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
下面是UserServlet代码：
Java code:
package cn.com.jobedu.blog;
import java.io.IOException;
import java.sql.SQLException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
public class UserServlet extends HttpServlet {
private static final long serialVersionUID = -1767037483934953543L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String method = request.getParameter("method");
if (
新手:
tomcat+struts 2.0
jsp 页面直接关联model
现在需要根据model(admin)里面的一个item(id),判断jsp页面出现的内容.
大概流程:
...
<table>
<tr>
<td>
<s:if admin.id is null> ......
搜索了一下：http://so.csdn.net/bbsSearchResult.aspx?q=jsp+%e4%bc%a0%e9%80%92&p=1，没有发现能用的。因为我是初学jsp，因此有些也许能用，只是我看不明白？
一、我的情形：
a.html 通过<form action=&q ......
