com.dxy.library.util.common.ListUtils Maven / Gradle / Ivy
package com.dxy.library.util.common;
import com.google.common.collect.Maps;
import org.apache.commons.lang3.math.NumberUtils;
import java.lang.reflect.Method;
import java.util.*;
/**
* List工具类
* @author duanxinyuan
* 2017/4/5 19:08
*/
public class ListUtils {
/**
* 判断数组是否为空
* @return false-为空
*/
public static boolean isEmpty(T[] list) {
return null == list || list.length == 0;
}
/**
* 判断数组是否为空
* @return false-为空
*/
public static boolean isNotEmpty(T[] list) {
return null != list && list.length > 0;
}
/**
* 判断List是否为空
* @return false-为空
*/
public static boolean isEmpty(List list) {
return null == list || list.size() == 0;
}
/**
* 判断List是否为空
* @return false-为空
*/
public static boolean isNotEmpty(List list) {
return null != list && list.size() > 0;
}
/**
* 升序排序
* @param list 要排序的list
* @param sortField 排序的字段
*/
public static void sortAsc(List list, final String sortField) {
sort(list, sortField, "asc");
}
/**
* 降序排序
* @param list 要排序的list
* @param sortField 排序的字段
*/
public static void sortDesc(List list, final String sortField) {
sort(list, sortField, "desc");
}
/**
* list排序
* @param list 要排序的list
* @param sortField 排序的字段
* @param sortMode 排序的模式（asc或者desc）
*/
private static void sort(List list, final String sortField, final String sortMode) {
Collections.sort(list, (obj1, obj2) -> {
int retVal;
try {
//首字母转大写
String newStr = sortField.substring(0, 1).toUpperCase() + sortField.replaceFirst("\\w", "");
String methodStr = "get" + newStr;
Method method1 = ((T) obj1).getClass().getMethod(methodStr, (Class) null);
Method method2 = ((T) obj2).getClass().getMethod(methodStr, (Class) null);
if (sortMode != null && "desc".equals(sortMode)) {
// 倒序
retVal = method2.invoke(obj2, (Object) null).toString().compareTo(method1.invoke(obj1, (Object) null).toString());
} else {
// 正序
retVal = method1.invoke(obj1, (Object) null).toString().compareTo(method2.invoke(obj2, (Object) null).toString());
}
} catch (Exception e) {
throw new RuntimeException();
}
return retVal;
});
}
/**
* 截取前几个数据
* @param blockSize 指定大小
*/
public static List sub(List list, int blockSize) {
List result = new ArrayList<>(blockSize);
for (int i = 0; i < list.size(); i++) {
if (i >= blockSize) {
break;
}
result.add(list.get(i));
}
return result;
}
/**
* 按照指定大小切割 list
* @param blockSize 指定大小
*/
public static List> split(List list, int blockSize) {
List> lists = new ArrayList<>();
if (list != null && blockSize > 0) {
int listSize = list.size();
if (listSize <= blockSize) {
lists.add(list);
return lists;
}
int batchSize = listSize / blockSize;
int remain = listSize % blockSize;
for (int i = 0; i < batchSize; i++) {
int fromIndex = i * blockSize;
int toIndex = fromIndex + blockSize;
lists.add(list.subList(fromIndex, toIndex));
}
if (remain > 0) {
lists.add(list.subList(listSize - remain, listSize));
}
}
return lists;
}
/**
* 从list中随机抽取1条数据
*/
private static List getRandom(List list) {
return getRandom(list, 1);
}
/**
* 从list中随机抽取n个元素
*/
private static List getRandom(List list, int n) {
HashMap map = Maps.newHashMap();
List listNew = new ArrayList();
if (list.size() <= n) {
return list;
} else {
while (map.size() < n) {
int random = (int) (Math.random() * list.size());
if (!map.containsKey(random)) {
map.put(random, "");
listNew.add(list.get(random));
}
}
return listNew;
}
}
/***
*从List中根据权重随机获取count个数据
*/
public static List getRandom(String[] keys, int[] weights, Integer count, List ts, List excepts, String verifyKy) {
if (keys == null || weights == null || keys.length != weights.length) {
return ts;
}
List weightElements = new ArrayList<>();
for (int i = 0; i < keys.length; i++) {
weightElements.add(new WeightElement(keys[i], weights[i]));
}
if (weightElements.size() == 0) {
return ts;
}
WeightElement ele0 = weightElements.get(0);
ele0.setThresholdLow(0);
ele0.setThresholdHigh(ele0.getWeight());
for (int i = 1; i < weightElements.size(); i++) {
WeightElement curElement = weightElements.get(i);
WeightElement preElement = weightElements.get(i - 1);
curElement.setThresholdLow(preElement.getThresholdHigh());
curElement.setThresholdHigh(curElement.getThresholdLow() + curElement.getWeight());
}
Random r = new Random();
Map> map = new TreeMap<>();
//根据权重配比 得到随机数
for (int i = 0; i < count; i++) {
Integer thresholdHigh = weightElements.get(weightElements.size() - 1).getThresholdHigh();
if (thresholdHigh == 0) {
continue;
}
Integer rv = r.nextInt(thresholdHigh);
if (rv < 0 || rv > weightElements.get(weightElements.size() - 1).getThresholdHigh() - 1) {
return null;
}
WeightElement randomValue;
//此时rv必然在0 - getMaxRandomValue()-1范围内，
//也就是必然能够命中某一个值
int start = 0, end = weightElements.size() - 1;
int index = weightElements.size() / 2;
while (true) {
if (rv < weightElements.get(index).getThresholdLow()) {
end = index - 1;
} else if (rv >= weightElements.get(index).getThresholdHigh()) {
start = index + 1;
} else {
randomValue = weightElements.get(index);
break;
}
index = (start + end) / 2;
}
String key = randomValue == null ? "" : randomValue.getKey();
if (!map.containsKey(key)) {
map.put(key, new ArrayList<>());
}
T t = ts.get(rv);
Object fieldValue = ReflectUtils.getFieldValue(t, verifyKy);
if (map.get(key).contains(rv) || (t != null && excepts.contains(NumberUtils.toLong(String.valueOf(fieldValue))))) {
count++;
//防止死循环
if (count >= 200) {
break;
}
} else {
map.get(key).add(rv);
}
}
List indexs = new ArrayList<>();
List result = new ArrayList<>();
map.forEach((k, v) -> indexs.addAll(v));
indexs.forEach(i -> result.add(ts.get(i)));
return result;
}
public static class WeightElement {
/**
* 元素标记
*/
private String key;
/**
* 元素权重
*/
private Integer weight;
/**
* 权重对应随机数范围低线
*/
private Integer thresholdLow;
/**
* 权重对应随机数范围高线
*/
private Integer thresholdHigh;
public WeightElement() {
}
public WeightElement(Integer weight) {
this.key = weight.toString();
this.weight = weight;
}
public WeightElement(String key, Integer weight) {
this.key = key;
this.weight = weight;
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
public Integer getWeight() {
return weight;
}
public void setWeight(Integer weight) {
this.weight = weight;
}
public Integer getThresholdLow() {
return thresholdLow;
}
public void setThresholdLow(Integer thresholdLow) {
this.thresholdLow = thresholdLow;
}
public Integer getThresholdHigh() {
return thresholdHigh;
}
public void setThresholdHigh(Integer thresholdHigh) {
this.thresholdHigh = thresholdHigh;
}
@Override
public String toString() {
return "key:" + this.key + " weight:" + this.weight + " low:" + this.thresholdLow + " heigh:" + this.thresholdHigh;
}
}
}
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