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第一篇笔记里面，我说groovy运行的居然还满快的，其实是个误会了。我上次做八皇后还是在8080上面用basic做的，和现在奔四上面的groovy相比是没有意义的。特地又做了个对比试验：
?
?1
int
?q
=
9
?2
int
[]?i
=
new
?
int
[q]
?3
int
?count
=
0
?4
long
?t?
=
?System.currentTimeMillis();
?5
scan(
0
)
?6
println(
"
totle?results:
"
+
count)
?7
println(
"
totle?time:
"
+
(System.currentTimeMillis()
-
t));
?8
def?scan(n)
{
?9
????if?(n==q)
{
10
????????println(i.toList())
11
????????count++
12
????????return
13
????}
14
????i[n]=0
15
????while(i[n]<q)
{
16
????????i[n]?=?i[n]+1
17
????????if?(check(n))
18
????????????scan(n+1)
19
????}
20
}
21
def?check(n)
{
22
????if?(n>0)
23
????????for?(j?in?0..<n)?
24
????????????if?(i[j]==i[n]?||?i[j]-i[n]==j-n?||?i[j]-i[n]==n-j?)
25
????????????????return?false
26
????return?true
27
}
运行结果是：totle time:7271 （为了用groovy控制台运行的，直接用groovy命令运行还要慢一点）
java呢？
queens.java:
?
?1
public
?
class
?queens?
{
?2
????static?int?q=9;
?3
????static?int[]?i=new?int[q];
?4
????static?int?count=0;
?5
????public?static?void?main(String[]?args)
{
?6
????????long?t?=?System.currentTimeMillis();
?7
????????scan(0);
?8
????????System.out.println("totle?results:"+count);
?9
????????System.out.println("totle?time:"+(System.currentTimeMillis()-t));
10
????}
11
????private?static?void?scan(int?n)
{
12
????????if?(n==q)
{
13
????????????for?(int?k=0;k<q;k++)?System.out.print(i[k]+(k==q-1?"/n":","));
14
????????????count++;
15
????????????return;
16
????????}
17
????????i[n]=0;
18
????????while(i[n]<q)
{
19
????????????i[n]?=?i[n]+1;
20
????????????if?(check(n))
{
21
????????????????scan(n+1);
22
????????????}
23
????????}
24
????}
25
????private?static?boolean?check(int?n)
{
26
????????for(int?j=0;j<n;j++)
{
27
????????????if?(i[j]==i[n]?||?i[j]-i[n]==j-n?||?i[j]-i[n]==n-j?)
{
28
????????????????return?false;
29
????????????}
30
????????}
31
????????return?true;
32
????}
33
}
34
运行结果是：totle time:271
每次运行花费的时间略有不同，groovy和java的运行速度看来大致相差10～30倍左右。
能说这是脚本语言天生的缺陷吗？我们来看看同样是类似java语法的脚本语言javascript在IE里面的速度：
?1
var?q
=
9
?
?2
var?i
=
[]?
?3
var?count
=
0
?
?4
var?d?
=
?
new
?Date();?
?5
scan(
0
)?
?6
document.write(
"
totle?results:
"
+
count
+
"
<br>
"
)?
?7
document.write(
"
time?used:
"
+
(
new
?Date()
-
d)
+
"
<br>
"
)?
?8
?9
function?scan(n)
{?
10
????if?(n==q)
{?
11
????????document.write(i+"<br>")?
12
????????count++?
13
????????return?
14
????}?
15
????i[n]=0?
16
????while(i[n]<q)
{
17
????????i[n]?=?i[n]+1?
18
????????if?(check(n))
{
19
????????????scan(n+1)?
20
????????}?
21
????}?
22
}
?
23
24
function?check(n)
{?
25
????for?(var?j=0;?j<n;j++)
26
????????if?(i[j]==i[n]?||?i[j]-i[n]==j-n?||?i[j]-i[n]==n-j?)
27
????????????return?false??
28
????return?true?
29
}
?
运行结果是： time used:1241
比groovy快了5倍以上。groovy可真是够慢的。
把groovy编译的class文件反编译了一下，看到groovy生成的代码效率确实是太低了，我们就看循环最内层的check函数吧：
1
def?check(n)
{
2
????if?(n>0)
3
????????for?(j?in?0..<n)?
4
????????????if?(i[j]==i[n]?||?i[j]-i[n]==j-n?||?i[j]-i[n]==n-j?)
5
????????????????return?false
6
????return?true
7
}
?
编译后变成
?1
????
public
?Object?check(Object?obj)
?2
????
{
?3
????????if(ScriptBytecodeAdapter.compareGreaterThan(obj,?new?Integer(0)))
?4
????????
{
?5
????????????Object?obj1?=?null;
?6
????????????for(Iterator?iterator?=?ScriptBytecodeAdapter.asIterator(ScriptBytecodeAdapter.createRange(new?Integer(0),?obj,?false));?iterator.hasNext();)
?7
????????????
{
?8
????????????????Object?obj2?=?iterator.next();
?9
????????????????Object?obj3?=?null;
10
????????????????if(ScriptBytecodeAdapter.asBool(ScriptBytecodeAdapter.asBool(ScriptBytecodeAdapter.compareEqual(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this,?"i"),?"getAt",?((Object)?(new?Object[]?
{
11
????obj2
12
}))),?ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this,?((Object)?(new?Object[]?
{
13
????obj
14
}))))?||?ScriptBytecodeAdapter.compareEqual(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this,?((Object)?(new?Object[]?
{
15
????obj2
16
}))),?"minus",?((Object)?(new?Object[]?
{
17
????ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this,?((Object)?(new?Object[]?
{
18
????????obj
19
????})))
20
}))),?ScriptBytecodeAdapter.invokeMethod(obj2,?((Object)?(new?Object[]?
{
21
????obj
22
}))))???((Object)?(Boolean.TRUE))?:?((Object)?(Boolean.FALSE)))?||?ScriptBytecodeAdapter.compareEqual(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this,?((Object)?(new?Object[]?
{
23
????obj2
24
}))),?((Object)?(new?Object[]?
{
25
????ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this,?((Object)?(new?Object[]?
{
26
????????obj
27
????})))
28
}))),?ScriptBytecodeAdapter.invokeMethod(obj,?((Object)?(new?Object[]?
{
29
????obj2
30
}))))???((Object)?(Boolean.TRUE))?:?((Object)?(Boolean.FALSE))))
31
????????????????????return?Boolean.FALSE;
32
????????????}
33
34
????????}
35
????????return?Boolean.TRUE;
36
????}
37
?
一切都是object，做任何事情都是invokeMethod，两个整数的比较居然要写将近400个字符的代码，光看代码量都可以吓倒我了。这是我们期待的脚本语言吗？
groovy可以嵌入到java代码里面，但是java代码可以嵌入到groovy里面吗？我觉得groovy有必要提供这样一种机制，在有必要的时候可以消除性能瓶颈。可是现在只看到groovy里面可以通过Scriptom（现在还是beta版）嵌入vbs、js脚本（包括使用WSH,FSO）或者调用InternetExplorer、Media Player、Word和Excel等windows组件。看来对消除性能瓶颈的帮助不大。
（编辑：李大同）
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