JAVA按金额平均分配任务量，随机分配，指定数量分配算法实例

需求背景

需要批量分配订单给人员，尽量保证分配到每个人的订单金额相近。可以按照金额平均分配，随机分配，指定数量分配。

思路分析

比如100个任务,每个任务ID和金额及号为(T100,100)…(T1,1)。第一轮分配先取最大的任务金额的分配给User1，即user1拥有T100，user2分配到T99，user3分配到T98。第二轮分配最小值，User1分配T1，User2分配T2，User3分配T3,第三轮分配最大值，即User1分配T97，User2分配T96，以此类推。

代码实现

• JDK必须是1.8及以上，代码中使用了1.8的特性，不多废话上代码

.

import java.io.*;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;

/**
 * @ClassName Allot
 * @Desc TODO
 * @Author chengp
 * @Date 2019/1/11 9:55
 * @Verion 1.0
 */
public class Allot {


    /**
     * 按金额分配
     *
     * @param users 人
     * @param tasks 任务
     * @return
     */
    public static Map<String, List<DemoTask>> allotOfAmount(List<DemoUser> users, List<DemoTask> tasks) {
        //Collections.shuffle(users);//随机排序
        Map<String, List<DemoTask>> allot = new ConcurrentHashMap<>(); //保存分配的信息
        if (users != null && users.size() > 0 && tasks != null && tasks.size() > 0) {
            List<DemoTask> copyTask = depCopy(tasks);//深拷贝,在处理过程中会删除已经分配的任务此处方便记录原始数据使用
            for (int n = 0; n < copyTask.size() + n; n++) {
                if (n % 2 == 0) {
                    copyTask = sortTask(copyTask, "desc");//正排
                } else {
                    copyTask = sortTask(copyTask, "asc");//倒排
                }
                for (int j = 0; j < users.size(); j++) {
                    if (copyTask.isEmpty()) break;
                    if (allot.containsKey(users.get(j).getUserId().toString())) {
                        List<DemoTask> list = allot.get(users.get(j).getUserId().toString());
                        list.add(copyTask.get(0));//每次取排序后的第一条
                        allot.put(users.get(j).getUserId().toString(), list);
                    } else {
                        List<DemoTask> list = new ArrayList<>();
                        list.add(copyTask.get(0));
                        allot.put(users.get(j).getUserId().toString(), list);
                    }
                    copyTask.remove(copyTask.get(0));//分配后删除

                }
            }
        }
        return allot;
    }

    /**
     * 平均分配&指定数量分配,多余的任务不予分配
     *
     * @param users 人
     * @param tasks 任务
     * @param count 每人指定分配数量
     * @return
     */
    public static Map<String, List<DemoTask>> allotOfAverage(List<DemoUser> users,   List<DemoTask> tasks, Integer count) {
        Collections.shuffle(users);//随机排序
        Collections.shuffle(tasks);
        Map<String, List<DemoTask>> allot = new ConcurrentHashMap<>(); //保存分配的信息
        if (users != null && users.size() > 0 && tasks != null && tasks.size() > 0) {
            for (int i = 0; i < tasks.size(); i++) {

                if (count != null && (i >= count * users.size())) {
                    break;
                }
                int j = i % users.size();
                if (allot.containsKey(users.get(j).getUserId().toString())) {
                    List<DemoTask> list = allot.get(users.get(j).getUserId().toString());
                    list.add(tasks.get(i));
                    allot.put(users.get(j).getUserId().toString(), list);
                } else {
                    List<DemoTask> list = new ArrayList<>();
                    list.add(tasks.get(i));
                    allot.put(users.get(j).getUserId().toString(), list);
                }
            }
        }
        return allot;
    }
    /**
     * 深拷贝
     *
     * @param srcList
     * @param 
     * @return
     */
    public static <T> List<T> depCopy(List<T> srcList) {
        ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
        try {
            ObjectOutputStream out = new ObjectOutputStream(byteOut);
            out.writeObject(srcList);

            ByteArrayInputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());
            ObjectInputStream inStream = new ObjectInputStream(byteIn);
            List<T> destList = (List<T>) inStream.readObject();
            return destList;
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }


    /**
     * 排序
     *
     * @param taskList
     * @param sort
     * @return
     */
    private static List<DemoTask> sortTask(List<DemoTask> taskList, String sort) {
        List<DemoTask> newList;
        if ("asc".equalsIgnoreCase(sort)) {//正序
            newList = taskList.stream().sorted(Comparator.comparing(DemoTask::getAmount))
                    .collect(Collectors.toList());
        } else if ("desc".equalsIgnoreCase(sort)) {//倒叙 reversed()即可
            newList = taskList.stream().sorted(Comparator.comparing(DemoTask::getAmount).reversed())
                    .collect(Collectors.toList());
        } else {
            newList = taskList;
        }
        return newList;
    }


    public static class  DemoUser{
        private Integer userId;
        private String userName;

        public Integer getUserId() {
            return userId;
        }

        public void setUserId(Integer userId) {
            this.userId = userId;
        }

        public String getUserName() {
            return userName;
        }

        public void setUserName(String userName) {
            this.userName = userName;
        }

        @Override
        public String toString() {
            return "DemoUser{" +
                    "userId=" + userId +
                    ", userName='" + userName + '\'' +
                    '}';
        }
    }


    public static class DemoTask implements Serializable{

        private Integer taskId;

        private BigDecimal amount;

        public Integer getTaskId() {
            return taskId;
        }

        public void setTaskId(Integer taskId) {
            this.taskId = taskId;
        }

        public BigDecimal getAmount() {
            return amount;
        }

        public void setAmount(BigDecimal amount) {
            this.amount = amount;
        }

        @Override
        public String toString() {
            return "DemoTask{" +
                    "taskId=" + taskId +
                    ", amount=" + amount +
                    '}'+'\n';
        }
    }
    public static void main(String[] args) {

        List<DemoUser> userList = new ArrayList<>();
        DemoUser entity = new DemoUser();
        entity.setUserId(1);
        userList.add(entity);
        DemoUser entity2 = new DemoUser();
        entity2.setUserId(2);
        userList.add(entity2);
        DemoUser entity3 = new DemoUser();
        entity3.setUserId(3);
        userList.add(entity3);

        List<DemoTask> taskList = new ArrayList<>();
        DemoTask apply1 = new DemoTask();
        apply1.setTaskId(1);
        apply1.setAmount(new BigDecimal(1000));
        taskList.add(apply1);
        DemoTask apply2 = new DemoTask();
        apply2.setTaskId(2);
        apply2.setAmount(new BigDecimal(1200));
        taskList.add(apply2);
        DemoTask apply3 = new DemoTask();
        apply3.setTaskId(3);
        apply3.setAmount(new BigDecimal(800));
        taskList.add(apply3);
        DemoTask apply4 = new DemoTask();
        apply4.setTaskId(5);
        apply4.setAmount(new BigDecimal(600));
        taskList.add(apply4);
        DemoTask apply5 = new DemoTask();
        apply5.setTaskId(5);
        apply5.setAmount(new BigDecimal(1600));
        taskList.add(apply5);
        DemoTask apply6 = new DemoTask();
        apply6.setTaskId(6);
        apply6.setAmount(new BigDecimal(2100));
        taskList.add(apply6);
        DemoTask apply7 = new DemoTask();
        apply7.setTaskId(7);
        apply7.setAmount(new BigDecimal(1210));
        taskList.add(apply7);

        DemoTask apply8 = new DemoTask();
        apply8.setTaskId(8);
        apply8.setAmount(new BigDecimal(1120));
        taskList.add(apply8);

        DemoTask apply9 = new DemoTask();
        apply9.setTaskId(9);
        apply9.setAmount(new BigDecimal(1310));
        taskList.add(apply9);

        DemoTask apply10 = new DemoTask();
        apply10.setTaskId(10);
        apply10.setAmount(new BigDecimal(1050));
        taskList.add(apply10);

        DemoTask apply11 = new DemoTask();
        apply11.setTaskId(11);
        apply11.setAmount(new BigDecimal(1500));
        taskList.add(apply11);
        List<DemoTask> copyTask = depCopy(taskList);

        Map<String, List<DemoTask>> map = allotOfAmount(userList,copyTask);

        System.out.println(map);
    }
}

执行结果：

结果分析：

根据结果看已经实现了我们要的效果了_！
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