Question

我在Daoimpl中编写了一个方法，并将列表返回给我的jsp。任何人都可以告诉我如何在我的jsp ???

中迭代和打印列表的值

错误：

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.bdisys.promorphics.domain.Blog

Dao方法：在这个dao方法中，我正在编写查询并将结果返回给jsp，有人告诉我如何打印这些值吗？

    public Map<String, Date> getTopBlogsQuesByDate()throws Exception {
             List<Blog> blogs = new ArrayList<Blog>(0);
             Map<String, Date> map = new HashMap<String, Date>();
             try{



                    String sql = "select title , date from (select blog_title as title ,created_date as date from  blog  union select ask_question as title , created_on as date from askquestions ) as aa order by date desc";
                    SQLQuery query = getSession().createSQLQuery(sql);
                    query.setResultTransformer(AliasToBeanResultTransformer); 


                    List l =query.list();
                    System.out.println("Total Number Of Records : "+l.size());
                    Iterator it = l.iterator();

                    while(it.hasNext())
                    {
                        Object o = (Object) it.next();
                        Blog b = (Blog)o;
                        b.setBlogTitle(b.getBlogTitle());
                        b.setCreatedDate(b.getCreatedDate());
                        map.put(b.getBlogTitle(), b.getCreatedDate());
                        System.out.println("Blog title Name : "+b.getBlogTitle());
                        System.out.println("Blog Date : "+b.getCreatedDate());

                        Askquestions a = (Askquestions)o;
                        a.setAskQuestion(a.getAskQuestion());
                        a.setCreatedQuesOn(a.getCreatedQuesOn());
                        System.out.println("Question title Name : "+a.getAskQuestion());
                        System.out.println("Question Date : "+a.getCreatedQuesOn());


                        map.put(a.getAskQuestion(), a.getCreatedQuesOn());

                        System.out.println("Unsorted HashMap: " + map);
                        TreeMap<String, Date> sortedHashMap = new TreeMap(map);     
                        System.out.println("Sorted HashMap: " + sortedHashMap); 

                    }        


             }
  catch(Exception e){
                e.printStackTrace();
            }finally{
                closeSession();
            }
         return map;
    }

Answer 1

要在jsp中打印hashMap，您可以使用JSTL forEach

<c:forEach items="${myMap}" var="entry">
    Key : <c:out value="${entry.key}"/>  Value: <c:out value="${entry.value}"/> <br />
</c:forEach>

迭代hashmap，并返回EntrySet。然后，您可以使用其getKey（）和getValue（）方法

注意：

将jstl库添加到类路径

在您的jsp顶部添加<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>。

Answer 2

您尚未将课程传递给AliasToBeanResultTransformer。

更改

query.setResultTransformer(AliasToBeanResultTransformer);

要

query.setResultTransformer(new AliasToBeanResultTransformer(Blog.class));

另见

AliasToBeanResultTransformer docs

如何在jsp中迭代以下代码？

2 个答案:

另见