C#中字典集合HashTable、Dictionary、ConcurrentDictionary三者区别

学习参考博客：http://www.cnblogs.com/yinrq/p/5584885.html

使用Stopwatch类测试耗时代码：

using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;

namespace WebApp
{
class Program
{
static Hashtable _hashtable;
static Dictionary<string, string> _dictionary;
static ConcurrentDictionary<string, string> _conDictionary;
static void Main(string[] args)
{
Compare(5000000);
Console.ReadLine();
Console.Read();
}

public static void Compare(int dataCount)
{
_hashtable = new Hashtable();
_dictionary = new Dictionary<string, string>();
_conDictionary = new ConcurrentDictionary<string, string>();
Stopwatch stopWatch = new Stopwatch();

// Hashtable
stopWatch.Start();
for (int i = 0; i < dataCount; i++)
{
_hashtable.Add("key" + i.ToString(), "Value" + i.ToString());
}
stopWatch.Stop();
Console.WriteLine("HashTable插" + dataCount + "条耗时(毫秒)：" + stopWatch.ElapsedMilliseconds);

//Dictionary
stopWatch.Reset();
stopWatch.Start();
for (int i = 0; i < dataCount; i++)
{
_dictionary.Add("key" + i.ToString(), "Value" + i.ToString());
}
stopWatch.Stop();
Console.WriteLine("Dictionary插" + dataCount + "条耗时(毫秒)：" + stopWatch.ElapsedMilliseconds);

//ConcurrentDictionary
stopWatch.Reset();
stopWatch.Start();
for (int i = 0; i < dataCount; i++)
{
_conDictionary.TryAdd("key" + i.ToString(), "Value" + i.ToString());
}
stopWatch.Stop();
Console.WriteLine("ConcurrentDictionary插" + dataCount + "条耗时(毫秒)：" + stopWatch.ElapsedMilliseconds);

// Hashtable
stopWatch.Reset();
stopWatch.Start();
for (int i = 0; i < _hashtable.Count; i++)
{
var key = _hashtable[i];
}
stopWatch.Stop();
Console.WriteLine("HashTable遍历时间(毫秒)：" + stopWatch.ElapsedMilliseconds);

//Dictionary
stopWatch.Reset();
stopWatch.Start();
for (int i = 0; i < _hashtable.Count; i++)
{
var key = _dictionary["key" + i.ToString()];
}
stopWatch.Stop();
Console.WriteLine("Dictionary遍历时间(毫秒)：" + stopWatch.ElapsedMilliseconds);

//ConcurrentDictionary
stopWatch.Reset();
stopWatch.Start();
for (int i = 0; i < _hashtable.Count; i++)
{
var key = _conDictionary["key" + i.ToString()];
}
stopWatch.Stop();
Console.WriteLine("ConcurrentDictionary遍历时间(毫秒)：" + stopWatch.ElapsedMilliseconds);
}
}
}

　　

最后总结：

大数据插入Dictionary花费时间最少

遍历HashTable最快是Dictionary的1/5,ConcurrentDictionary的1/10

单线程建议用Dictionary，多线程建议用ConcurrentDictionary或者HashTable（Hashtable tab = Hashtable.Synchronized(new Hashtable());获得线程安全的对象）