C# 返回 ConcurrentBag 的副本

Question

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections.Concurrent;

namespace Crystal_Message
{
    class Message
    {
        private int messageID;
        private string message;
        private ConcurrentBag <Employee> messageFor;
        private Person messageFrom;
        private string calltype;

        public Message(int iden,string message, Person messageFrom, string calltype, string telephone)
        {
            this.messageID = iden;
            this.messageFor = new ConcurrentBag<Employee>();
            this.Note = message;
            this.MessageFrom = messageFrom;
            this.CallType = calltype;
        }

        public ConcurrentBag<Employee> ReturnMessageFor
        {
            get
            {

                return messageFor;
            }

        }

        public int MessageIdentification
        {
            get { return this.messageID; }

            private set
            {
                if(value == 0)
                {
                    throw new ArgumentNullException("Must have Message ID");
                }

                this.messageID = value;
            }

        }

        public string Note
        {
            get { return message; }

            private set
            {
                if (string.IsNullOrWhiteSpace(value))
                {
                    throw new ArgumentException("Must Have a Message");

                }
                this.message = value;


            }

        }

        public Person MessageFrom
        {
            get { return messageFrom; }

            private set
            {
                this.messageFrom = value;
            }

        }

        public string CallType
        {
            get { return this.calltype; }

            private set
            {
                if (string.IsNullOrWhiteSpace(value))
                {
                    throw new ArgumentNullException("Please specify call type");
                }

                this.calltype = value;

            }

        }

        public void addEmployee(Employee add)
        {
            messageFor.Add(add);
        }


        public override string ToString()
        {
            return "Message: " + this.message + " From: " + this.messageFrom + " Call Type: " + this.calltype + " For: " + this.returnMessagefor();
        }

        private string returnMessagefor() 
        {
            string generate="";

            foreach(Employee view in messageFor)
            {
                generate += view.ToString() + " ";
            }

            return generate;
        }

        public override bool Equals(object obj)
        {
            if (obj == null)
            {
                return false;
            }

            Message testEquals = obj as Message;

            if((System.Object)testEquals == null)
            {
                return false;
            }

            return (this.messageID == testEquals.messageID) && (this.message == testEquals.message) && (this.messageFor == testEquals.messageFor) && (this.messageFrom == testEquals.messageFrom) && (this.calltype == testEquals.calltype);

        }

        public bool Equals(Message p)
        {
            if ((Object)p == null)
            {
                return false;
            }

            return (this.messageID == p.messageID) && (this.message == p.message) && (this.messageFor == p.messageFor) && (this.messageFrom == p.messageFrom) && (this.calltype == p.calltype);

        }

        public override int GetHashCode()
        {


            unchecked
            {
                return this.messageID.GetHashCode() * 33 ^ this.message.GetHashCode() * 33 ^ this.messageFor.GetHashCode() * 33 ^ this.messageFrom.GetHashCode() * 33 ^ this.calltype.GetHashCode();
            }


        }

    }
}

我有一个 Message 类，用户可以在其中为多个人留言。我有一个 setter/getter ，但是，是否按照我正确练习的方式返回一个 ConcurrentBag<>？如果没有，我如何返回 ConcurrentBag<> 以便我可以遍历它并显示它？

Answer 1

ConcurrentBag<T>是一个 IEnumerable<T> .您可以像往常一样遍历它。但是，由于这是一个线程安全的集合，因此使用它存在性能问题。

如果您想在循环时摆脱性能影响，请调用 ToArray在它上面并返回新数组。

    public IEnumerable<Employee> ReturnMessageFor
    {
        get
        {

            return messageFor.ToArray();
        }

    }