springMVC实体用注解管理,多对多 set集合元素排序问题 解决

实现效果 分类在set集合里不可排序 现要使商家拥有的相同的分来在同一列,需要把set集合里的元素放入list 但是问题是页面是双循环,必须以 . 的形式取集合元素所以需要把list集合声明到实体中,只做临时存储,所以写到dto类,这样就可排序了 我们用一个内部类Collections 的sort ( ....)方法来排序 , 这样内层循环就可以取到拍好序的元素,从而达到目的

    jsp页面

<c:forEach items="${businessList}" var="businessDto">
  <c:forEach items="${businessDto.busniessAssortList}" var="busniessAssort" varStatus="_index">
	<a style="border:2px solid #DBDBDB;padding: 2px 4px;margin-left:3px;"  title="修改" href="${pageContext.request.contextPath}/adminBusiness/toUpdateBusinessAssort.do?id=${businessDto.id}&busniessAssortDto.id=${busniessAssort.id}">
	${busniessAssort.name}  
	</a><label style="font-size:20px;color:red;cursor: pointer;" onclick="delBusinessAssortRef(${businessDto.id},${busniessAssort.id});" >⊗</label>
  </c:forEach>
</c:forEach>

 

实体:

pojo 类

        
@Entity
@Table(name = "BUSINESS")
@JsonAutoDetect
@JsonIgnoreProperties(value = { "hibernateLazyInitializer", "shopkeeper",
        "dishAssorts", "busniessAssorts", "empBusRefs", "orders",
        "orderDetails", "userAccounts", "activities"})
public class Business implements java.io.Serializable {
        //分类set
        private Set<BusniessAssort> busniessAssorts = new HashSet<BusniessAssort>(0);
        @ManyToMany(mappedBy = "businesss", cascade = { CascadeType.PERSIST })
	public Set<BusniessAssort> getBusniessAssorts() {
		return busniessAssorts;
	}

	public void setBusniessAssorts(Set<BusniessAssort> busniessAssorts) {
		this.busniessAssorts = busniessAssorts;
	}
        /*
       其他get/set方法
         */


} 

dto 类

public class BusinessDto extends Business implements java.io.Serializable,Comparable<BusinessDto> {
    //页面取这个集合即可得到处理后的元素顺序
    private List<BusniessAssort> busniessAssortList = new ArrayList<BusniessAssort>();//排序
    
    
    public List<BusniessAssort> getBusniessAssortList() {
        return busniessAssortList;
    }

    public void setBusniessAssortList(List<BusniessAssort> busniessAssortList) {
        this.busniessAssortList = busniessAssortList;
    }
} 

执行的 controllor 层方法

       /**
	 * for admin
	 */
	@RequestMapping("/toAdminBusniessAssort.do")
	public String toBusinessInfo(BusinessDto businessDto) {
		Pager pager = this.calculatePagedInfo();
		pager.setPageSize(pager.getPageSize()>20 ? pager.getPageSize() : 20); 
		businessDto.setDishType(1L);
		//第一层排序 
 		List<BusinessDto> businessList = businessService.getBusinessAllForAdmin(pager, businessDto);
		 Collections.sort(businessList,new Comparator<BusinessDto>() {
 			public int compare(BusinessDto o1, BusinessDto o2) {				
				 return o2.getId().compareTo(o1.getId());
			 }
 		});
                第二层排序 
                for (BusinessDto businessDto2 : businessList) {
			//分类排序
			List<BusniessAssort> busniessAssortList = new ArrayList<BusniessAssort>();
			busniessAssortList.addAll(businessDto2.getBusniessAssorts());
			businessDto2.setBusniessAssortList(busniessAssortList);
			Collections.sort(businessDto2.getBusniessAssortList(),new Comparator<BusniessAssort>() {
				public int compare(BusniessAssort o1, BusniessAssort o2) {				
					return o2.getId().compareTo(o1.getId());
				}
			});
		}
		if(businessDto!=null){
			if(StringUtils.hasText(businessDto.getName())){
				this.getRequest().setAttribute("name", businessDto.getName());				
			}
		}
		
		this.getRequest().setAttribute("businessList", businessList);//这里只能把businessList 传到页面 
		return "admin/business/adminBusAssortRef";
	}