之所以要测试这个方法,是因为项目中要使用该方法动态创建需要对象。
上次说了方法Activator.CreateInstance()创建对象和直接用表达式创建对象的性能比较。被老赵等大牛批评测试方法不对,我决定再测试一下,测试环境和第一次一样。
测试代码如下(其中Form1就是新建的一个WinForm,什么代码都没有写):
上次说了方法Activator.CreateInstance()创建对象和直接用表达式创建对象的性能比较。被老赵等大牛批评测试方法不对,我决定再测试一下,测试环境和第一次一样。
测试代码如下(其中Form1就是新建的一个WinForm,什么代码都没有写):
代码
1 Stopwatch watch1 = new Stopwatch();
2 watch1.Start();
3 for (int i = 0; i < 10000; i++)
4 {
5 Form1 form1 = Activator.CreateInstance(typeof(Form1)) as Form1;
6 }
7
8 watch1.Stop();
9 Console.WriteLine("Activator.CreateInstance");
10 Console.WriteLine(watch1.Elapsed.ToString());
11
12 watch1.Reset();
13 watch1.Start();
14 for (int i = 0; i < 10000; i++)
15 {
16 Form form1 = GetCache.InstanceCacheEx.InstanceCache(typeof(Form1)) as Form1;
17 }
18 watch1.Stop();
19 Console.WriteLine("Expression.CreateInstanceEx");
20 Console.WriteLine(watch1.Elapsed.ToString());
2 watch1.Start();
3 for (int i = 0; i < 10000; i++)
4 {
5 Form1 form1 = Activator.CreateInstance(typeof(Form1)) as Form1;
6 }
7
8 watch1.Stop();
9 Console.WriteLine("Activator.CreateInstance");
10 Console.WriteLine(watch1.Elapsed.ToString());
11
12 watch1.Reset();
13 watch1.Start();
14 for (int i = 0; i < 10000; i++)
15 {
16 Form form1 = GetCache.InstanceCacheEx.InstanceCache(typeof(Form1)) as Form1;
17 }
18 watch1.Stop();
19 Console.WriteLine("Expression.CreateInstanceEx");
20 Console.WriteLine(watch1.Elapsed.ToString());
而创建Expression Tree的代码如下:
创建Expression Tree,并缓存
1 public class InstanceCachesEx
2 {
3 private Dictionary<Type, Func<object>> dicEx = new Dictionary<Type, Func<object>>();
4 public object InstanceCache(Type key)
5 {
6
7 object value = null;
8
9 if (dicEx.TryGetValue(key, out value))
10 {
11 return value();
12 }
13 else
14 {
15 value = CreateInstance(key);
16 dicEx[key] = value;
17 return value();
18 }
19 }
20
21 static Func<object> CreateInstance(Type type)
22 {
23 NewExpression newExp = Expression.New(type);
24 Expression<Func<object>> lambdaExp = Expression.Lambda<Func<object>>(newExp, null);
25 Func<object> func = lambdaExp.Compile();
26 return func;
27 }
28 }
29
30 public static class GetCache
31 {
32 static GetCache()
33 {
34 InstanceCacheEx = new InstanceCachesEx();
35 }
36
37 public static InstanceCachesEx InstanceCacheEx { get; set; }
38 }
2 {
3 private Dictionary<Type, Func<object>> dicEx = new Dictionary<Type, Func<object>>();
4 public object InstanceCache(Type key)
5 {
6
7 object value = null;
8
9 if (dicEx.TryGetValue(key, out value))
10 {
11 return value();
12 }
13 else
14 {
15 value = CreateInstance(key);
16 dicEx[key] = value;
17 return value();
18 }
19 }
20
21 static Func<object> CreateInstance(Type type)
22 {
23 NewExpression newExp = Expression.New(type);
24 Expression<Func<object>> lambdaExp = Expression.Lambda<Func<object>>(newExp, null);
25 Func<object> func = lambdaExp.Compile();
26 return func;
27 }
28 }
29
30 public static class GetCache
31 {
32 static GetCache()
33 {
34 InstanceCacheEx = new InstanceCachesEx();
35 }
36
37 public static InstanceCachesEx InstanceCacheEx { get; set; }
38 }
测试结果如下:
Activator.CreateInstance:
00:00:00.0140537
Expression.CreateInstanceEx:
00:00:00.7389382
00:00:00.0140537
Expression.CreateInstanceEx:
00:00:00.7389382
吆呼,差了这么多......
我们换一个类来试试,来一个简单的类:
public class Class1 { }
再来看看测试结果:
Activator.CreateInstance
00:00:00.0020066
Expression.CreateInstance
00:00:00.0078841
00:00:00.0020066
Expression.CreateInstance
00:00:00.0078841
嗯?结果方法Activator.CreateInstance()比表达式树要快了。
待续......