logic    
     
      <%        Dog dog1=new Dog();        dog1.setAge(2);        dog1.setName("xiaoming");                 Dog dog2=new Dog();        dog2.setAge(2);        dog2.setName("xiaoming");         Dog dog3=new Dog();        dog3.setAge(2);        dog3.setName("xiaoming");                LinkedList linkedList=new LinkedList();        linkedList.add(dog1);        linkedList.add(dog2);        linkedList.add(dog3);        request.setAttribute("dogList",linkedList);     %>          
      
strust-logic
     
      
                ${dog.name}||${dog.age}     
      name:是指域对象的名字。id是要集合中的单个对象    
      
       
                 ww不存在
           
       
        判断不为空
        
                 dogList中存在的
            
        
         
                       ${dog.age }大于20 
         如果name这个对象的属性大于20就输出。