Java封装一个根据指定的字段来获取子集的工具类-编程知识

工具类

ZhLambdaUtils

@SuppressWarnings("all")
public class ZhLambdaUtils {/*** METHOD_NAME*/private static final String METHOD_NAME = "writeReplace";/*** 获取到lambda参数的方法名称** @param <T>      parameter* @param function function* @return the name* @since 2023.1.1*/public static <T> String getLambdaMethodName(FilterUtils.ZhFunction<T, ?> function) {try {return ((SerializedLambda) MethodUtils.invokeMethod(function, true, METHOD_NAME)).getImplMethodName();} catch (Exception e) {throw new RuntimeException(e);}}/*** Method to property** @param name name* @return the string* @since 2023.1.1*/public static String methodToProperty(String name) {if (name.startsWith("is")) {name = name.substring(2);} else {if (!name.startsWith("get") && !name.startsWith("set")) {throw new IllegalArgumentException("Error parsing property name '" + name + "'.  Didn't start with 'is', 'get' or 'set'.");}name = name.substring(3);}if (name.length() == 1 || name.length() > 1 && !Character.isUpperCase(name.charAt(1))) {name = name.substring(0, 1).toLowerCase(Locale.ENGLISH) + name.substring(1);}return name;}/*** Is property** @param name name* @return the boolean* @since 2023.1.1*/public static boolean isProperty(String name) {return isGetter(name) || isSetter(name);}/*** Is getter** @param name name* @return the boolean* @since 2023.1.1*/public static boolean isGetter(String name) {return name.startsWith("get") && name.length() > 3 || name.startsWith("is") && name.length() > 2;}/*** Is setter** @param name name* @return the boolean* @since 2023.1.1*/public static boolean isSetter(String name) {return name.startsWith("set") && name.length() > 3;}}

SelectSubsetUtils

该工具类可以实现通过对象的指定字段实现双向遍历

/***  通过本级唯一key值，以及本级字段、父级字段迭查询所有本级的子集*/
@UtilityClass
public class SelectSubsetUtils {/*** Filter** @param <D>    parameter* @param origin 需要被过滤的数据集* @param left   本级唯一key -例如code* @param right  本级与父级关联key值 -例如parentCode* @param adjust 本级唯一key值过滤条件* @return the list* @since 2023.1.1*/public static <D> List<D> filterSon(List<D> origin, ZhFunction<D, ?> left, ZhFunction<D, ?> right, Adjust adjust) {return filter(origin, left, right, adjust, false);}/*** Filter parent** @param <D>    parameter* @param origin 需要被过滤的数据集* @param left   本级唯一key -例如code* @param right  本级与父级关联key值 -例如parentCode* @param adjust 本级唯一key值过滤条件* @return the list* @since 2023.1.1*/public static <D> List<D> filterParent(List<D> origin, ZhFunction<D, ?> left, ZhFunction<D, ?> right, Adjust adjust) {return filter(origin, left, right, adjust, true);}/*** Filter** @param <D>      parameter* @param origin   origin* @param left     left* @param right    right* @param adjust   adjust* @param reverset reverset* @return the list* @since 2023.1.1*/private static <D> List<D> filter(List<D> origin, ZhFunction<D, ?> left, ZhFunction<D, ?> right,Adjust adjust, Boolean reverset) {//过滤全量数据按照本级唯一key进行过滤List<D> ds = origin.stream().filter(o -> {//通过反射获取到传递进来的本级唯一key值Object value = getObject(left, o);return adjust.test(value);}).collect(Collectors.toList());//调用与父级关联的key值进行递归过滤if (reverset) {// 如果是反转，那么就是父级过滤return filter(origin, ds, left, right);} else {// 如果是正常，那么就是子级过滤return filter(origin, ds, right, left);}}/*** Filter** @param <D>    parameter* @param origin 需要被过滤的数据源* @param filter 被过滤后的数据集* @param left   本级唯一key -例如code* @param right  本级与父级关联key值 -例如parentCode* @return the list* @since 2023.1.1*/private static <D> List<D> filter(List<D> origin, List<D> filter, ZhFunction<D, ?> left, ZhFunction<D, ?> right) {//构建本级过滤的数据，然后拿出来跟全量数据再次进行比对List<D> list = new LinkedList<>(filter);if (CollectionUtils.isEmpty(filter)) {return list;}//遍历过滤后的数据集filter.forEach(f -> {//跟全量的数据进行比较List<D> ds = origin.stream().filter(o -> {//将全量的数据和过滤出的数据进行比较，找出后续的子节点Object value = getObject(left, o);Object value2 = getObject(right, f);return value.equals(value2);}).collect(Collectors.toList());if (CollectionUtils.isEmpty(ds)) {return;}//递归调用list.addAll(filter(origin, ds, left, right));});return list;}/*** 获取值** @param <D>        parameter* @param firstFiled first filed* @param d          d* @return object object* @since 2023.1.1*/private static <D> Object getObject(ZhFunction<D, ?> firstFiled, D d) {String lambdaMethodName = ZhLambdaUtils.getLambdaMethodName(firstFiled);//获取到字段名称String fieldName = ZhLambdaUtils.methodToProperty(lambdaMethodName);Object value = null;try {Field field = FieldUtils.getDeclaredField(d.getClass(), fieldName, true);value = field.get(d);} catch (Exception e) {throw new RuntimeException(e);}return value;}/*** 自定义判断函数*/@FunctionalInterfacepublic interface Adjust {/*** Test** @param value value* @return the boolean* @since 2023.1.1*/boolean test(Object value);}/*** 自定义 Serializable 函数接口，这个接口有大用，至于为什么可以看下面参考博客*/@FunctionalInterfacepublic interface ZhFunction<T, R> extends Function<T, R>, Serializable {}}

测试

寻找字段 Code 为 1681497872765722624，并且关联的父级code为 ParentCode 的所有子集

public static void main(String[] args) {List<A> list = new ArrayList<>();A a = new A("1", "1681497872765722624");A a2 = new A("1681497872765722624", "1681498005196677120");A a3 = new A("1681497872765722624", "1681498062989991936");A a4 = new A("1681497872765722624", "1681498151091347456");A a5 = new A("1681498151091347456", "2");A a6 = new A("1681498151091347456", "3");A a7 = new A("8", "7");A a8 = new A("", "8");list.add(a);list.add(a2);list.add(a3);list.add(a4);list.add(a5);list.add(a6);list.add(a7);list.add(a8);List<A> target = filter(list, A::getCode, A::getParentCode, "1681497872765722624"::equals);target.forEach(System.out::println);
}