第一篇筆記里面，我說(shuō)groovy運(yùn)行的居然還滿(mǎn)快的，其實(shí)是個(gè)誤會(huì)了。我上次做八皇后還是在8080上面用basic做的，和現(xiàn)在奔四上面的groovy相比是沒(méi)有意義的。特地又做了個(gè)對(duì)比試驗(yàn)： 1 int q=9
2int[] i=new int[q]
3int count=0
4long t = System.currentTimeMillis();
5scan(0)
6println("totle results:"+count)
7println("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 }
21def 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}
運(yùn)行結(jié)果是：totle time:7271 （為了用groovy控制臺(tái)運(yùn)行的，直接用groovy命令運(yùn)行還要慢一點(diǎn)）
java呢？ queens.java: 1public 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 運(yùn)行結(jié)果是：totle time:271
每次運(yùn)行花費(fèi)的時(shí)間略有不同，groovy和java的運(yùn)行速度看來(lái)大致相差10～30倍左右。
能說(shuō)這是腳本語(yǔ)言天生的缺陷嗎？我們來(lái)看看同樣是類(lèi)似java語(yǔ)法的腳本語(yǔ)言javascript在IE里面的速度：
1var q=9
2var i=[]
3var count=0
4var d = new Date();
5scan(0)
6document.write("totle results:"+count+"<br>")
7document.write("time used:"+(new Date()-d)+"<br>")
8
9function 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
24function 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}
運(yùn)行結(jié)果是： time used:1241
比groovy快了5倍以上。groovy可真是夠慢的。
把groovy編譯的class文件反編譯了一下，看到groovy生成的代碼效率確實(shí)是太低了，我們就看循環(huán)最內(nèi)層的check函數(shù)吧：
1def 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}
編譯后變成
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, "i"), "getAt", ((Object) (new Object[] {
13 obj
14})))) || ScriptBytecodeAdapter.compareEqual(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this, "i"), "getAt", ((Object) (new Object[] {
15 obj2
16}))), "minus", ((Object) (new Object[] {
17 ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this, "i"), "getAt", ((Object) (new Object[] {
18 obj
19 })))
20}))), ScriptBytecodeAdapter.invokeMethod(obj2, "minus", ((Object) (new Object[] {
21 obj
22})))) ? ((Object) (Boolean.TRUE)) : ((Object) (Boolean.FALSE))) || ScriptBytecodeAdapter.compareEqual(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this, "i"), "getAt", ((Object) (new Object[] {
23 obj2
24}))), "minus", ((Object) (new Object[] {
25 ScriptBytecodeAdapter.invokeMethod(ScriptBytecodeAdapter.getGroovyObjectProperty(this, "i"), "getAt", ((Object) (new Object[] {
26 obj
27 })))
28}))), ScriptBytecodeAdapter.invokeMethod(obj, "minus", ((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，兩個(gè)整數(shù)的比較居然要寫(xiě)將近400個(gè)字符的代碼，光看代碼量都可以嚇倒我了。這是我們期待的腳本語(yǔ)言嗎？
groovy可以嵌入到j(luò)ava代碼里面，但是java代碼可以嵌入到groovy里面嗎？我覺(jué)得groovy有必要提供這樣一種機(jī)制，在有必要的時(shí)候可以消除性能瓶頸。可是現(xiàn)在只看到groovy里面可以通過(guò)Scriptom（現(xiàn)在還是beta版）嵌入vbs、js腳本（包括使用WSH,FSO）或者調(diào)用InternetExplorer、Media Player、Word和Excel等windows組件。看來(lái)對(duì)消除性能瓶頸的幫助不大。
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