[ Java 文章收集 ] Java SE 6.0 內建 Javascript 引擎測試

來源自 這裡 
Preface: 
Java SE 6.0 採納 JSR 223 建議，使得 Java 能夠與眾多 Script 語言協同運作，透過 Java 定義的標準 API，能夠讓 Script 直接存取和控制 Java 的物件，而Java 應用程式當中也能夠直接內嵌 Script 環境。Java SE 6 的 javax.script package 定義了 Script API，裡面共實作了六個介面和六個類別，如下: 
- 介面 

Bindings: A mapping of key/value pairs, all of whose keys are Strings.
Compilable: The optional interface implemented by ScriptEngines whose methods compile scripts to a form that can be executed repeatedly without recompilation.
Invocable: The optional interface implemented by ScriptEngines whose methods allow the invocation of procedures in scripts that have previously been executed.
ScriptContext: The interface whose implementing classes are used to connect Script Engines with objects, such as scoped Bindings, in hosting applications.
ScriptEngine: ScriptEngine is the fundamental interface whose methods must be fully functional in every implementation of this specification.
ScriptEngineFactory: ScriptEngineFactory is used to describe and instantiate ScriptEngines.

- 類別 

AbstractScriptEngine: Provides a standard implementation for several of the variants of the eval method.
CompiledScript: Extended by classes that store results of compilations.
ScriptEngineManager:
The ScriptEngineManager implements a discovery and instantiation mechanism for ScriptEngine classes and also maintains a collection of key/value pairs storing state shared by all engines created by the Manager.
SimpleBindings:A simple implementation of Bindings backed by a HashMap or some other specified Map.
SimpleScriptContext: Simple implementation of ScriptContext.

範例01：第一個 Hello World 程式 

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1. package test.scripts;  
2.   
3. import javax.script.ScriptEngine;  
4. import javax.script.ScriptEngineManager;  
5. import javax.script.ScriptException;  
6.   
7. public class JSDemo1 {  
8.     public static void main(String args[])  
9.     {  
10.         ScriptEngineManager mgr = new ScriptEngineManager(); // 建立一個 Script 管理員  
11.         ScriptEngine jsEngine = mgr.getEngineByName("JavaScript"); // 取得 Javascript 引擎  
12.         try {  
13.           jsEngine.eval("print('Hello, world!')"); // 透過 Javascript 引擎解譯 print('hello, world') 命令  
14.         } catch (ScriptException ex) {  
15.             ex.printStackTrace();  
16.         }   
17.     }  
18. }  

範例02：列舉 Java 環境支援的 Script 引擎 

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1. package test.scripts;  
2.   
3. import java.util.List;  
4.   
5. import javax.script.ScriptEngineFactory;  
6. import javax.script.ScriptEngineManager;  
7.   
8. public class JSDemo2 {  
9.   
10.     /** 
11.      * BD: 範例02：列舉 Java 環境支援的 Script 引擎 
12.      * @param args 
13.      */  
14.     public static void main(String[] args) {  
15.         ScriptEngineManager mgr = new ScriptEngineManager();  
16.         List factories = mgr.getEngineFactories();  
17.         for (ScriptEngineFactory factory : factories) {  
18.             System.out.println("ScriptEngineFactory Info");  
19.   
20.             String engName = factory.getEngineName(); // 引擎名稱  
21.             String engVersion = factory.getEngineVersion(); // 引擎版本  
22.             String langName = factory.getLanguageName(); // Script 語言  
23.             String langVersion = factory.getLanguageVersion(); // 語言版本  
24.   
25.             System.out.printf("\tScript Engine: %s (%s)\n", engName, engVersion);  
26.             List engNames = factory.getNames();  
27.             for (String name : engNames) {  
28.                 System.out.printf("\t\tEngine Alias: %s\n", name);  
29.             }  
30.   
31.             System.out.printf("\tLanguage: %s (%s)\n", langName, langVersion);  
32.         }  
33.     }  
34. }  

執行結果: 

ScriptEngineFactory Info
Script Engine: Mozilla Rhino (1.6 release 2)
Engine Alias: js
Engine Alias: rhino
Engine Alias: JavaScript
Engine Alias: javascript
Engine Alias: ECMAScript
Engine Alias: ecmascript
Language: ECMAScript (1.6)

範例03：搜尋指定的 Script 引擎 

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1. package test.scripts;  
2.   
3. import java.util.List;  
4.   
5. import javax.script.ScriptEngine;  
6. import javax.script.ScriptEngineFactory;  
7. import javax.script.ScriptEngineManager;  
8.   
9. public class JSDemo3 {  
10.   
11.     /** 
12.      * BD: 範例03：搜尋指定的 Script 引擎 
13.      * @param args 
14.      */  
15.     public static void main(String[] args) {  
16.         ScriptEngineManager mgr = new ScriptEngineManager();  
17.         List scriptFactories = mgr.getEngineFactories();  
18.         for (ScriptEngineFactory factory : scriptFactories) {  
19.             String langName = factory.getLanguageName();  
20.             String langVersion = factory.getLanguageVersion();  
21.             if (langName.startsWith("ECMAScript") && langVersion.startsWith("1.6")) { // 比對指定的與名稱和版本  
22.                 ScriptEngine engine = factory.getScriptEngine();  
23.                 System.out.printf("Engine:%s\n", engine);  
24.                 break;  
25.             }  
26.         }  
27.     }  
28. }  

範例04：執行外部 javasript 檔案 
考慮有如下的 js 檔案: 
- hellp.js 

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1. var str="Hello world, welcome to the universe.";  
2. var n=str.indexOf("welcome");  
3. print(str+" "+n);  

接著你可以如下執行該 js 檔案: 

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1. package test.scripts;  
2.   
3. import java.io.FileInputStream;  
4. import java.io.InputStream;  
5. import java.io.InputStreamReader;  
6. import java.io.Reader;  
7.   
8. import javax.script.ScriptEngine;  
9. import javax.script.ScriptEngineManager;  
10. import javax.script.ScriptException;  
11.   
12. public class JSDemo4 {  
13.   
14.     /** 
15.      * BD: 範例04：執行外部 javasript 檔案 
16.      * @param args 
17.      */  
18.     public static void main(String[] args) throws Exception {  
19.         ScriptEngineManager engineMgr = new ScriptEngineManager();  
20.         ScriptEngine engine = engineMgr.getEngineByName("ECMAScript");  
21.         InputStream is = new FileInputStream("hello.js");  
22.         try {  
23.             Reader reader = new InputStreamReader(is);  
24.             engine.eval(reader);  
25.         } catch (ScriptException ex) {  
26.             ex.printStackTrace();  
27.         }  
28.     }  
29. }  

執行結果: 

Hello world, welcome to the universe. 13

範例05：透過 Invocable 介面喚起 Javascript 函數 

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1. package test.scripts;  
2.   
3. import javax.script.Invocable;  
4. import javax.script.ScriptEngine;  
5. import javax.script.ScriptEngineManager;  
6. import javax.script.ScriptException;  
7.   
8. public class JSDemo5 {  
9.   
10.     /** 
11.      * BD: 範例05：透過 Invocable 介面喚起 Javascript 函數 
12.      * @param args 
13.      */  
14.     public static void main(String[] args) {  
15.         ScriptEngineManager engineMgr = new ScriptEngineManager();  
16.         ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
17.         try {  
18.             jsEngine.eval("function sayHello() {" +  
19.                         "  println('Hello, world!');" +  
20.                         "}");  
21.             Invocable invocableEngine = (Invocable) jsEngine;  
22.             invocableEngine.invokeFunction("sayHello");  
23.         } catch (ScriptException ex) {  
24.             ex.printStackTrace();  
25.         } catch (NoSuchMethodException nsme){  
26.             nsme.printStackTrace();  
27.         }  
28.     }  
29. }  

執行結果: 

Hello, world!

範例06：Script 直接存取 Java 物件 

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1. package test.scripts;  
2.   
3. import java.util.ArrayList;  
4. import java.util.List;  
5.   
6. import javax.script.ScriptEngine;  
7. import javax.script.ScriptEngineManager;  
8. import javax.script.ScriptException;  
9.   
10. public class JSDemo6 {  
11.     /** 
12.      * BD: 範例06：Script 直接存取 Java 物件  
13.      * @param args 
14.      */  
15.     public static void main(String args[]) {  
16.         List namesList = new ArrayList();  
17.         namesList.add("Jill");  
18.         namesList.add("Bob");  
19.         namesList.add("Laureen");  
20.         namesList.add("Ed");  
21.         ScriptEngineManager engineMgr = new ScriptEngineManager();  
22.         ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
23.         jsEngine.put("namesListKey", namesList); // 將 java 變數指定給 javascript 環境中的 nameListKey 變數  
24.         System.out.println("Executing in script environment…");  
25.         try {  
26.             // 列印 Java 的 nameList 變數內容，並新增一個 Dana 字串資料到 List 尾端  
27.             jsEngine.eval("var x;" + "var names = namesListKey.toArray();"  
28.                     + "for(x in names) {" + "  println(names[x]);" + "}"  
29.                     + "namesListKey.add(\"Dana\");");  
30.         } catch (ScriptException ex) {  
31.             ex.printStackTrace();  
32.         }  
33.         System.out.println("Executing in Java environment…");  
34.         for (String name : namesList) {  
35.             System.out.println(name);  
36.         }  
37.     }  
38. }  

執行結果: 

Executing in script environment…
Jill
Bob
Laureen
Ed
Executing in Java environment…
Jill
Bob
Laureen
Ed
Dana

範例07：透過 Invocable 將參數值傳遞給 Javascript 中的函數 

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1. package test.scripts;  
2.   
3. import java.util.ArrayList;  
4. import java.util.List;  
5.   
6. import javax.script.Invocable;  
7. import javax.script.ScriptEngine;  
8. import javax.script.ScriptEngineManager;  
9. import javax.script.ScriptException;  
10.   
11. public class JSDemo7 {  
12.   
13.     /** 
14.      * BD: 範例07：透過 Invocable 將參數值傳遞給 Javascript 中的函數 
15.      * @param args 
16.      */  
17.     public static void main(String[] args) {  
18.         List namesList = new ArrayList();  
19.         namesList.add("Jill");  
20.         namesList.add("Bob");  
21.         namesList.add("Laureen");  
22.         namesList.add("Ed");  
23.         ScriptEngineManager engineMgr = new ScriptEngineManager();  
24.         ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
25.         Invocable invocableEngine = (Invocable) jsEngine;  
26.         try {  
27.             System.out.printf("\t[Info] Execute in JS:\n");  
28.             jsEngine.eval("function printNames1(namesList) {" + "  var x;"  
29.                     + "  var names = namesList.toArray();"  
30.                     + "  for(x in names) {" + "    println(names[x]);" + "  }"  
31.                     + "}" + "function addName(namesList, name) {"  
32.                     + "  namesList.add(name);" + "}");  
33.             invocableEngine.invokeFunction("printNames1", namesList);  
34.             invocableEngine.invokeFunction("addName", namesList, "Dana");  
35.             System.out.printf("\t[Info] Execute in Java:\n");  
36.             for(String name:namesList) System.out.println(name);  
37.         } catch (ScriptException ex) {  
38.             ex.printStackTrace();  
39.         } catch (NoSuchMethodException ex) {  
40.             ex.printStackTrace();  
41.         }  
42.     }  
43. }  

執行結果: 

[Info] Execute in JS:
Jill
Bob
Laureen
Ed
[Info] Execute in Java:
Jill
Bob
Laureen
Ed
Dana

範例08：script 使用 Java 的 package 

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1. package test.scripts;  
2.   
3. import javax.script.ScriptEngine;  
4. import javax.script.ScriptEngineManager;  
5. import javax.script.ScriptException;  
6.   
7. public class JSDemo8 {  
8.   
9.     /** 
10.      * BD: 範例08：script 使用 Java 的 package 
11.      * @param args 
12.      */  
13.     public static void main(String[] args) {  
14.         ScriptEngineManager engineMgr = new ScriptEngineManager();  
15.         ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
16.         try {  
17.             jsEngine.eval("importPackage(javax.swing);" + "var optionPane = "  
18.                     + "  JOptionPane.showMessageDialog(null, 'Hello, world!');");  
19.         } catch (ScriptException ex) {  
20.             ex.printStackTrace();  
21.         }  
22.     }  
23. }  

Supplement: 
* W3Schools.com > JavaScript tutorial 
* jrunscript - command line script shell 
* Wiki > Rhino (JavaScript engine)