public
								class User {
  private String username;
  
  public String getUsername() {
    return username;
  }
  
  publicvoid setUsername(String username) {
    this.username = username;
  }
}
				

						public
						class UserForm extends FormBean {
  private User user;
  
  public User getUser() {
    return user;
  }
  
  publicvoid setUser(User user) {
    this.user = user;
  }
}

						<
						html:text
						property
						="user.username"
						/>
				

						
<script>
// 表单验证函数function validateForm(form) {
  // this.user.username 会报错
  alert( form['user.username'] );
  if(form['user.username'] .value == "") {
    alert("用户名不能为空!");
    return false;
  }
  return true;
}
</script>
				

						<
						form 
						onsubmit
						="return validateForm(this);"
						>
						<
						input 
						name
						="user.username"
						/>
						</
						form
						>
				

//为什么所有的action都要继承Action? 
public class LoginAction extends Action{ 
//为什么都是execute方法.可以给它改名吗? 
public ActionForward execute(ActionMapping mapping, Actionform form, 
HttpServletRequest request, HttpServletResponse response)throws AuctionException { 
//为什么要将form强制类型转换为Loginform,form里不是已经获取从页面提交的数据了吗?为什么不可以直接用form呢?还要类型转换? 
Loginform loginform = (Loginform)form; 
if ("123".equals(loginform.getUsername() && "123".equals(loginform.getPassword()){ 
return mapping.findForward("success"); 
}else{ 
return mapping.findForward("success"); 
} 
} 
} 

class 非文盲
{
    abstract method 写字(笔 pen);
}
//那你要找一个人来写字, 那它必须符合条件:
class 大学生 extends 非文盲
{
    method 写字(笔 pen) {
        // 他会选择用自己喜欢的笔写字, 例如 钢笔
        钢笔 myPen = (钢笔)pen;
        myPen.吸墨水();
        开始写字_用(myPen);
    }
}