本工具类为按对象属性排序工具类,实现的功能:
1.按对象的一个属性和多个属性进行排序.
2.按对象属性正序和倒序排列.
3.完美支持int等基础类和Integer等包装类.
4.完美支持属性为实现了Comparable接口的类.
5.如果类不是java.lang中定义的基础类型也没有实现Comparable接口则转为String后进行排序.

实现思路:使用反射取得对象属性或对象方法的值从而解除对具体对象的依赖.

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.List;

/**
* 通用工具类之按对象中某属性排序
* @author 李坤
* 交流博客:http://blog.csdn.net/lk_blog
*/
public class SortListUtil {
public static final String DESC = "desc";
public static final String ASC = "asc";

/**
* 对list中的元素按升序排列.
*
* @param list
* 排序集合
* @param field
* 排序字段
* @return
*/
public static List< > sort(List< > list, final String field) {
return sort(list, field, null);
}

/**
* 对list中的元素进行排序.
*
* @param list
* 排序集合
* @param field
* 排序字段
* @param sort
* 排序方式: SortList.DESC(降序) SortList.ASC(升序).
* @return
*/
@SuppressWarnings("unchecked")
public static List< > sort(List< > list, final String field,
final String sort) {
Collections.sort(list, new Comparator() {
public int compare(Object a, Object b) {
int ret = 0;
try {
Field f = a.getClass().getDeclaredField(field);
f.setAccessible(true);
Class< > type = f.getType();

if (type == int.class) {
ret = ((Integer) f.getInt(a)).compareTo((Integer) f
.getInt(b));
} else if (type == double.class) {
ret = ((Double) f.getDouble(a)).compareTo((Double) f
.getDouble(b));
} else if (type == long.class) {
ret = ((Long) f.getLong(a)).compareTo((Long) f
.getLong(b));
} else if (type == float.class) {
ret = ((Float) f.getFloat(a)).compareTo((Float) f
.getFloat(b));
} else if (type == Date.class) {
ret = ((Date) f.get(a)).compareTo((Date) f.get(b));
} else if (isImplementsOf(type, Comparable.class)) {
ret = ((Comparable) f.get(a)).compareTo((Comparable) f
.get(b));
} else {
ret = String.valueOf(f.get(a)).compareTo(
String.valueOf(f.get(b)));
}

} catch (SecurityException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
if (sort != null && sort.toLowerCase().equals(DESC)) {
return -ret;
} else {
return ret;
}

}
});
return list;
}