org.apache.jasper.JasperException: javax.servlet.jsp.JspException: javax.faces.FacesException: javax.faces.FacesException: Can't instantiate class: 'org.test.web.LoginAct'.. class org.test.web.LoginAct : java.sql.SQLException: Already closed
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:375)
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:810)
com.sun.faces.context.ExternalContextImpl.dispatch(ExternalContextImpl.java:322)
com.sun.faces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:147)
com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:87)
com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200)
com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:117)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:198)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

不能实例化org.test.web.LoginAct这个类。

那是什么愿因呢，我在登录界面的基础上又作了一个显示学生信息的表格
这样写有错误么？这是LoginAct的那个类
package org.test.web;

import java.sql.SQLException;
import java.util.List;

import javax.faces.model.DataModel;
import javax.faces.model.ListDataModel;

import org.test.server.StudentManager;

public class LoginAct {
private String name;
private String password;
private DataModel DataStudent=new ListDataModel();

public LoginAct()throws SQLException{
StudentManager sManager=new StudentManager();
List list=sManager.GetStudent();
DataStudent.setWrappedData(list);
}

public String login(){
if(name.equals("abc")&&password.equals("123")){
return "loginok";
}
else{
return "loginfalse";
}
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public DataModel getDataStudent() {
return DataStudent;
}

public void setDataStudent(DataModel dataStudent) {
this.DataStudent = dataStudent;
}

}

class org.test.web.LoginAct : java.sql.SQLException: Already closed
这跟数据库联接有问题么

StudentManager sManager=new StudentManager();
List list=sManager.GetStudent();
DataStudent.setWrappedData(list);
看一下有数据没

我在那设了断点了，可每执行到那就错了

把你的构造方法改了，你这样写页面无法用。
[CODE]
public LoginAct()throws SQLException{
StudentManager sManager=new StudentManager();
List list=sManager.GetStudent();
DataStudent.setWrappedData(list);
}
[/CODE]
页面上调用getUserList就可以了，你返回的类型不对。
[CODE]
private DataModel userList ; //数据列表
/**
* 取得数据列表
* @return
*/
public DataModel getUserList() {
if(userList == null) {
userList = new ListDataModel();
userList.setWrappedData(getAllUserList());
}
return userList;
}
[/CODE]