按对象中某一属性排序

1.Comparable接口是在java.lang类中的，而Comparator接口是在java.util类中的。
2.Comparable 是在集合内部定义的方法实现的排序，Comparator 是在集合外部实现的排序，所以，如想实现排序，就需要在集合外定义 Comparator 接口的方法或在集合内实现 Comparable 接口的方法。

用自定义类实现 Comparable接口，那么这个类就具有排序功能，Comparable和具体你要进行排序的类的实例邦定。

而Comparator比较灵活，它没有和任何类绑定，实现它的自定义类仅仅定义了一种排序方式或排序规则。不言而喻，这种方式比较灵活。我们的要排序的类可以分别和多个实现 Comparator接口的类绑定，从而达到可以按自己的意愿实现按多种方式排序的目的。Comparable——“静态绑定排序”,Comparator——“动态绑定排序”。

 

排序：

 Collections.sort(lists, new comparator(){                         

int compare(Object o1, Object o2) {     
        Member m1=(Member)o1;
        Member m2=(Member)o2;        
        // 按姓名排序
        return m1.getName().compareTo(m2.getName();
   }   
});  

 根据第一个参数小于、等于或大于第二个参数分别返回负整数、零或正整数

 

属性为String型：(动态加载对象属性的get方法)

 

   1. public class SortList<E>{   
   2.     public void Sort(List<E> list, final String method, final String sort){  
   3.         Collections.sort(list, new Comparator() {             
   4.             public int compare(Object a, Object b) {  
   5.                 int ret = 0;  
   6.                 try{  
   7.                     Method m1 = ((E)a).getClass().getMethod(method, null);  
   8.                     Method m2 = ((E)b).getClass().getMethod(method, null);  
   9.                     if(sort != null && "desc".equals(sort))//倒序  
  10.                         ret = m2.invoke(((E)b), null).toString().compareTo(m1.invoke(((E)a), null).toString());   
  11.                     else//正序  
  12.                         ret = m1.invoke(((E)a), null).toString().compareTo(m2.invoke(((E)b), null).toString());  
  13.                 }catch(NoSuchMethodException ne){  
  14.                     System.out.println(ne);  
  15.                 }catch(IllegalAccessException ie){  
  16.                     System.out.println(ie);  
  17.                 }catch(InvocationTargetException it){  
  18.                     System.out.println(it);  
  19.                 }  
  20.                 return ret;  
  21.             }  
  22.          });  
  23.     }  
  24. }  

 

  m1:

 

public java.lang.Integer com.openb2c.openreport.DayReport.getOrderSize()

完整连接：

1.http://wenku.baidu.com/view/a19a50ea81c758f5f61f674a.html

2.http://jardot.iteye.com/blog/762349

 

 

DayReport.java类：

public class DayReport extends BaseReport{

	private String date;
	private Double totalFee;
	private Double refundFee;
	private Double getMoney;
	private Double postFee;
	private Integer orderSize;	
	
	private Long productNum;  //产品数，即符合条件的订单中有多少个产品
	private Integer backProductNum; //退款通过的订单中产品的个数
	private Integer backOrderNum;  //退款通过的订单个数
	
	public String getDate() {
		return date;
	}
	public void setDate(String date) {
		this.date = date;
	}
	public Double getTotalFee() {
		return totalFee;
	}
	public void setTotalFee(Double totalFee) {
		this.totalFee = totalFee;
	}
	public Double getRefundFee() {
		return refundFee;
	}
	public void setRefundFee(Double refundFee) {
		this.refundFee = refundFee;
	}
	public Double getGetMoney() {
		return getMoney;
	}
	public void setGetMoney(Double getMoney) {
		this.getMoney = getMoney;
	}
	public Double getPostFee() {
		return postFee;
	}
	public void setPostFee(Double postFee) {
		this.postFee = postFee;
	}
	public Integer getOrderSize() {
		return orderSize;
	}
	public void setOrderSize(Integer orderSize) {
		this.orderSize = orderSize;
	}
	
	public Long getProductNum() {
		return productNum;
	}
	public void setProductNum(Long productNum) {
		this.productNum = productNum;
	}
	public Integer getBackProductNum() {
		return backProductNum;
	}
	public void setBackProductNum(Integer backProductNum) {
		this.backProductNum = backProductNum;
	}
	public Integer getBackOrderNum() {
		return backOrderNum;
	}
	public void setBackOrderNum(Integer backOrderNum) {
		this.backOrderNum = backOrderNum;
	}
}

 

 

1、对Double型数据排序（通用方法）：

/**
     * 给Double型排序
     * method 为DayReport中属性的 get方法名如：getOrderSize
     * sort 为排序
     *check 为选择的条件如1天内、1月内等
     */
	@SuppressWarnings("unchecked")
	public static  void SortDouble (List<DayReport> list,final String method,final String sort){		
		
		Comparator comparator = new Comparator(){
			public int compare(Object a, Object b) {	
				int ret = 0;  
				try {
					 Method m1 = ((DayReport)a).getClass().getMethod(method, null);
					 Method m2 = ((DayReport)b).getClass().getMethod(method, null);
					 double m=(Double) m1.invoke((DayReport)a);
					 double n=(Double) m2.invoke((DayReport)b);
					 double c=m-n;
					
						if(c>0.0)//倒序  							
						{
							if(sort.equals("DESC")){
								ret=-1;  //本来
							}else{
								ret=1;
							}						
						}
						else if(c<0.0){
							if(sort.equals("DESC")){
								ret=1;
							}else{
								ret=-1;
							}	
						}else{
							ret=0;
						}						
				} catch (SecurityException e) {
					StringBuilder msg = new StringBuilder("Double类型数据排序时出现异常！");
					Debug.logError(e,msg.toString(), module);
				} catch (NoSuchMethodException e) {
					StringBuilder msg = new StringBuilder("Double类型数据排序时出现异常！");
					Debug.logError(e,msg.toString(), module);
				} catch (IllegalAccessException e) {
					StringBuilder msg = new StringBuilder("Double类型数据排序时出现异常！");
					Debug.logError(e,msg.toString(), module);
				} catch (InvocationTargetException e) {
					StringBuilder msg = new StringBuilder("Double类型数据排序时出现异常！");
					Debug.logError(e,msg.toString(), module);
				}  
				return ret;
			}			
		};
		Collections.sort(list,comparator);
	}

 2.对Int型排序（通用方法）

/**
     * 给int型排序
     */
	@SuppressWarnings("unchecked")
	public static  void SortInt (List<DayReport> list,final String method,final String sort){	
		
		/*Comparator comparator = new Comparator(){
			public int compare(Object a, Object b) {
				Integer aa = ((DayReport) a).getOrderSize();
				Integer bb = ((DayReport) b).getOrderSize();
				Integer cc = aa - bb;
				if (cc > 0)
					return 1;
				if (cc < 0)
					return -1;
				else
					return 0;
			}
		};
		Collections.sort(list,comparator);
	}*/
		Comparator comparator = new Comparator() {
			public int compare(Object a, Object b) {
				int ret = 0;
			
					Method m1 = ((DayReport) a).getClass().getMethod(method,
							null);
					Method m2 = ((DayReport) b).getClass().getMethod(method,
							null);
					Integer m = (Integer) m1.invoke((DayReport) a);
					Integer n = (Integer) m2.invoke((DayReport) b);
					Integer c = m - n;

					if (c > 0)// 倒序
					{
						if (sort.equals("DESC")) {
							ret = -1; // 本来
						} else {
							ret = 1;
						}
					} else if (c < 0) {
						if (sort.equals("DESC")) {
							ret = 1;
						} else {
							ret = -1;
						}
					} else {
						ret = 0;
					}
				
				return ret;
			}
		};
		Collections.sort(list, comparator);
	}

 

使用：

 

<th><a href="<@ofbizUrl>queryDay?check=${check?if_exists}&method=getTotalFee&sort=${orderby?if_exists}</@ofbizUrl>">销售额</a></th>
          <th><a href="<@ofbizUrl>queryDay?check=${check?if_exists}&method=getRefundFee&sort=${orderby?if_exists}</@ofbizUrl>">退款额</a></th>

 

 

String method=(String)context.get("method");
        String  sort=(String)context.get("sort");
        if(UtilValidate.isEmpty(sort)){        		
    		sort="ASC";
    	}else{
			if (UtilValidate.areEqual(sort, "ASC")) {
				sort = "DESC";
			} else {
				sort = "ASC";
			}
    	}
        
        if(UtilValidate.isNotEmpty(method)){  
        	if(method.equals("getOrderSize")){
        		DayReportService.SortInt(finallyList,method,sort);
        	}else{
        		DayReportService.SortDouble(finallyList,method,sort);
        	}
        }  
		result.put("finallyList", finallyList);	
		result.put("sort", sort);
		result.put("check", check);

评论

1 楼 mm4409092 2013-11-07  

Java通用工具类之按对象属性排序工具类
http://blog.csdn.net/lk_blog/article/details/12804873