手写比较器comparator

项目中需要对一些数据进行排序，应用到了个比较强大的比较器，感觉还是很不错的，贴上代码：

public class XXXComparator<E> {
    private final Logger log = Logger.getLogger(XXXComparator.class);

    @SuppressWarnings({ "unchecked", "rawtypes" })
    public void sort(List<E> list, final String method, final String sortType) {
        // list 要比较的list 对象列表
       // method传入相应的get方法签名
      // sortType  desc or asc

        Collections.sort(list, new Comparator() {

            public int compare(Object a, Object b) {
                int ret = 0;
                try {
                    Method m1 = ((E) a).getClass().getMethod(method, null);
                    Method m2 = ((E) b).getClass().getMethod(method, null);
                    if (sortType != null && "desc".equals(sortType)) {
                        ret = m2.invoke(((E) b), null).toString()
                                .compareTo(m1.invoke(((E) a), null).toString());
                    } else {
                        ret = m1.invoke(((E) a), null).toString()
                                .compareTo(m2.invoke(((E) b), null).toString());
                    }
                } catch (NoSuchMethodException e) {
                    log.error(e);
                } catch (InvocationTargetException e) {
                    log.error(e);
                } catch (IllegalAccessException e) {
                    log.error(e);
                }
                return ret;
            }
        });
    }

}

比如我有一个People对象，里面有  name, age 等属性，
现在我有一个People的list列表，需要进行排序，如按name或者age排

好了，可以这么写：

XXXComparator<People> sortList = new XXXComparator<People>();
String method = "getName"; //or  'getAge'
String orderByType = "desc";
sortList.sort(peopleList, method, orderByType);

这样就可以实现按 属性排序了



对以上comparator进行了优化，如果类型为int的数据应用以上方法会存在问题

public class XXXComparator<E> {
    private final Logger log = Logger.getLogger(XXXComparator.class);

    @SuppressWarnings({ "unchecked", "rawtypes" })
    public void sort(List<E> list, final String methodName, final String sortType) {
        Collections.sort(list, new Comparator() {

            public int compare(Object a, Object b) {
                int ret = 0;
                try {

                    Method method = a.getClass().getMethod(methodName);

                    Object aResult = method.invoke(a);
                    Object bResult = method.invoke(b);

                    if (aResult == null) {
                        return -1;
                    }
                    if (bResult == null) {
                        return 1;
                    }
                    if (aResult instanceof String) {
                        String com1 = "desc".equals(sortType) ? (String) aResult : (String) bResult;
                        String com2 = "desc".equals(sortType) ? (String) bResult : (String) aResult;
                        log.info("aResult= " + aResult + "\nbResult= " + bResult);
                        return com1.toLowerCase().compareTo(com2.toLowerCase());

                    }

                    if (aResult instanceof Comparable) {
                        Comparable com1 = "desc".equals(sortType) ? (Comparable) aResult
                                : (Comparable) bResult;
                        Comparable com2 = "desc".equals(sortType) ? (Comparable) bResult
                                : (Comparable) aResult;
                        return com1.compareTo(com2);

                    }

                } catch (NoSuchMethodException e) {
                    log.error(e);
                } catch (InvocationTargetException e) {
                    log.error(e);
                } catch (IllegalAccessException e) {
                    log.error(e);
                }
                return ret;
            }
        });
    }

}