javaBean的各种工具方法

1.listToMap将list集合转换成map集合

public static Map listToMap(String keyName, List list) {Map map &＃61; Maps.newHashMap();if (CollectionUtils.isNotEmpty(list)) {for (V val : list) {try {PropertyDescriptor pd &＃61; new PropertyDescriptor(keyName,val.getClass());Method getMethod &＃61; pd.getReadMethod();// 获得get方法Object o &＃61; getMethod.invoke(val);// 执行get方法返回一个Objectif (o !&＃61; null) {map.put((K) o, val);}} catch (IllegalAccessException | IllegalArgumentException| InvocationTargetException | IntrospectionException e) {e.printStackTrace();}}}return map;}2.listToMapList将list集合转换成Map>

// listToMap&＃xff0c;1个key对应的是1个元素// listToMapList&＃xff0c;1个key对应的是1个list。list中属性id一样的&＃xff0c;放到1个小的list中。// 可以去掉k,v这2个参数public static Map> listToMapList(String keyName,List list) {Map> map &＃61; Maps.newHashMap();if (CollectionUtils.isNotEmpty(list)) {for (V val : list) {try {PropertyDescriptor pd &＃61; new PropertyDescriptor(keyName,val.getClass());Method getMethod &＃61; pd.getReadMethod();// 获得get方法Object o &＃61; getMethod.invoke(val);// 执行get方法返回一个Objectif (o !&＃61; null) {List valueList &＃61; map.get((K) o);if (valueList &＃61;&＃61; null) {valueList &＃61; Lists.newArrayList();}valueList.add(val);map.put((K) o, valueList);}} catch (IllegalAccessException | IllegalArgumentException| InvocationTargetException | IntrospectionException e) {e.printStackTrace();}}}return map;}3.beanToMap将一个JavaBean转换成map集合

public static Map bean2Map(Object obj) {if (obj &＃61;&＃61; null) {return null;}Map map &＃61; Maps.newHashMap();try {BeanInfo beanInfo &＃61; Introspector.getBeanInfo(obj.getClass());PropertyDescriptor[] propertyDescriptors &＃61; beanInfo.getPropertyDescriptors();for (PropertyDescriptor property : propertyDescriptors) {String key &＃61; property.getName();// 过滤class属性if (!key.equalsIgnoreCase("class")) {// 得到property对应的getter方法Method getter &＃61; property.getReadMethod();Object value &＃61; getter.invoke(obj);map.put(key, value);}}} catch (Exception e) {e.printStackTrace();}return map;}4.map批量过滤key的值

public static Map MapFilter(Map map,final List keys) {return Maps.filterKeys(map, new Predicate() {&＃64;Overridepublic boolean apply(String input) {return keys.contains(input) ? false : true;}});}5.提取集合中的对象的一个属性, 组合成List

public static List extractToList(final Collection collection,final String propertyName) {if (CollectionUtils.isEmpty(collection)) {return null;}List list &＃61; new ArrayList(collection.size());CollectionUtils.collect(collection, new BeanToPropertyValueTransformer(propertyName), list);return list;}6.将一个字符串按指定规则分割然后类型转换&＃xff0c;放入list中

public static List stringToLongList(String str,String separator){List idList &＃61; Lists.newArrayList();String[] idArray &＃61; str.split(separator);if(idArray !&＃61; null){for(String id:idArray){idList.add(Long.valueOf(id));}}return idList;}