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DataUtils.java
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package common.util;
import com.alibaba.fastjson.JSON;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.helpers.MessageFormatter;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.function.Function;
import java.util.stream.Collectors;
/**
* Created by nibnait on 2021/08/18
*/
@Slf4j
public class DataUtils {
/**
* 分批调rpc接口 查询数据
* @param list 入参 eg: skuIdList
* @param size 一批的数量 eg: 100
* @param function 一个lambda表达式 eg: skuIdList -> itemsSkuService.batchQuery(skuIdList)
* @return 将每一次的返回值，用 flatMap 打平 返回一个 list
*/
public static <T, R> List<R> getDataPartition(List<T> list, Integer size, Function<List<T>, List<R>> function) {
return Lists.partition(list, size).stream()
.map(function)
.flatMap(Collection::stream)
.filter(Objects::nonNull)
.collect(Collectors.toList());
}
/**
* 返回 list1 - (list1 ∩ list2)
*/
public static <T> List<T> difference(Collection<T> list1, Collection<T> list2) {
return Lists.newArrayList(Sets.difference(Sets.newHashSet(list1), Sets.newHashSet(list2)));
}
/**
* 返回交集 list1 ∩ list2
*/
public static <T> List<T> intersection(Collection<T> list1, Collection<T> list2) {
return Lists.newArrayList(Sets.intersection(Sets.newHashSet(list1), Sets.newHashSet(list2)));
}
/**
* @param format abc{}e
* @param args d
* @return abcde
*/
public static String format(String format, Object... args) {
return MessageFormatter.arrayFormat(format, args).getMessage();
}
/**
* @param clazz 类型不可为抽象类/接口
*/
public static <T> T parseObject(String s, Class<T> clazz) {
if (StringUtils.isBlank(s) || "null".equalsIgnoreCase(s)) {
try {
return clazz.newInstance();
} catch (InstantiationException | IllegalAccessException e) {
log.error(e.getMessage(), e);
return null;
}
}
try {
return JSON.parseObject(s, clazz);
} catch (Throwable e) {
log.error(e.getMessage(), e);
return null;
}
}
public static <T> List<T> parseArray(String s, Class<T> clazz) {
if (StringUtils.isBlank(s) || "null".equalsIgnoreCase(s)) {
return Lists.newArrayList();
}
return JSON.parseArray(s, clazz);
}
public static String toJsonStringObject(Object o) {
if (o == null) {
return JSON.toJSONString(Maps.newHashMap());
}
return JSON.toJSONString(o);
}
public static String toJsonStringArray(Object o) {
if (o == null) {
return JSON.toJSONString(Lists.newArrayList());
}
return JSON.toJSONString(o);
}
/**
* 将 element 加到 list 中
*/
public static <T> List<T> addToList(T element, List<T> list) {
list = CollectionUtils.isEmpty(list) ? Lists.newArrayList() : list;
if (element != null) {
list.add(element);
return list.stream().distinct().collect(Collectors.toList());
}
return CollectionUtils.isEmpty(list) ? null : list;
}
/**
* 将 element 加到 list 中
*/
public static <T> List<T> addToList(List<T> element, List<T> list) {
list = CollectionUtils.isEmpty(list) ? Lists.newArrayList() : list;
if (CollectionUtils.isNotEmpty(element)) {
list.addAll(element);
return list.stream().distinct().collect(Collectors.toList());
}
return CollectionUtils.isEmpty(list) ? null : list;
}
/**
* 将 element 从 list 中删除
*/
public static <T> List<T> removeElement(T element, List<T> list) {
if (CollectionUtils.isEmpty(list)) {
return list;
}
CopyOnWriteArrayList<T> cowList = new CopyOnWriteArrayList<>(list);
cowList.removeIf(t -> t.equals(element));
return cowList;
}
/**
* 返回 list中 重复的元素
*/
public static <T> List<T> getDuplicateElements(List<T> list) {
return list.stream()
.collect(Collectors.toMap(e -> e, e -> 1, Integer::sum))
.entrySet().stream()
.filter(e -> e.getValue() > 1)
.map(Map.Entry::getKey)
.collect(Collectors.toList());
}
/**
* 判断 list 中 是否包含 t
*/
public static <T> boolean contains(List<T> list, T t) {
return CollectionUtils.isNotEmpty(list) && list.contains(t);
}
}