实现java.util.Comparator接口，对对象集合进行多属性组合排序
Commons - BeanUtils 提供了很多功能，其中一个很有用的是对对象集合进行排序，如Collections.sort(peoples, new BeanComparator("age"));
另外，可以使用java.util.Collections的sort方法可以对collection集合进行排序，包括多列组合排序，下面是自己实现java.util.Comparator，定制对象属性排序规则的例子：
package com.lph.test;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.LinkedList;
/**
*
* 自定义对象多属性（多列）组合排序
* <p>Title: is a Class</p>
*
* <p>Description: 类</p>
*
* <p>Copyright: Copyright (c) 2006</p>
*
* <p>Company: sunrise</p>
*
* @author islph
* @version 1.0
*/
public class CompositeComparator implements Comparator {
/** in the condition list, comparators' priority decrease from head to tail */
private List comparators = new LinkedList();
/** get the comparators, you can manipulate it as need. */
public List getComparators() {
return comparators;
}
/** add a batch of comparators to the condition list */
public void addComparators(Comparator[] comparatorArray) {
if (comparatorArray == null) {
return;
}
for (int i = 0; i < comparatorArray.length; i++) {
comparators.add(comparatorArray[i]);
}
}
/** compare by the priority */
public int compare(Object o1, Object o2) {
for (Iterator iterator = comparators.iterator(); iterator.hasNext();) {
Comparator comparator = (Comparator) iterator.next();
int result = comparator.compare(o1, o2);
if (result != 0) {
return result;
}
}
return 0;
}
}
// 多列排序；按属性COUNTY_NO镇，DDP_ID终端 组合排序
CompositeComparator myComparator = new CompositeComparator();
myComparator.addComparators(
new Comparator[] {
new Comparator() {
public int compare(Object a, Object b) {
DisplayForm aObj, bObj;
aObj = (DisplayForm) a;
bObj = (DisplayForm) b;
String aStr = (String) aObj.get("COUNTY_NO");
String bStr = (String) bObj.get("COUNTY_NO");
return aStr.compareTo(bStr);
}
}
, new Comparator() {
public int compare(Object a, Object b) {
DisplayForm aObj, bObj;
aObj = (DisplayForm) a;
bObj = (DisplayForm) b;
String aStr = (String) aObj.get("DDP_ID");
String bStr = (String) bObj.get("DDP_ID");
return aStr.compareTo(bStr);
}
}
});
java.util.Collections.sort(listResult, myComparator);
