程式扎記: [ Java 文章收集 ] Java SE 6.0 內建 Javascript 引擎測試

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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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package test.scripts;  
  
import javax.script.ScriptEngine;  
import javax.script.ScriptEngineManager;  
import javax.script.ScriptException;  
  
public class JSDemo1 {  
    public static void main(String args[])  
    {  
        ScriptEngineManager mgr = new ScriptEngineManager(); // 建立一個 Script 管理員  
        ScriptEngine jsEngine = mgr.getEngineByName("JavaScript"); // 取得 Javascript 引擎  
        try {  
          jsEngine.eval("print('Hello, world!')"); // 透過 Javascript 引擎解譯 print('hello, world') 命令  
        } catch (ScriptException ex) {  
            ex.printStackTrace();  
        }   
    }  
}  

範例02：列舉 Java 環境支援的 Script 引擎

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package test.scripts;  
  
import java.util.List;  
  
import javax.script.ScriptEngineFactory;  
import javax.script.ScriptEngineManager;  
  
public class JSDemo2 {  
  
    /** 
     * BD: 範例02：列舉 Java 環境支援的 Script 引擎 
     * @param args 
     */  
    public static void main(String[] args) {  
        ScriptEngineManager mgr = new ScriptEngineManager();  
        List factories = mgr.getEngineFactories();  
        for (ScriptEngineFactory factory : factories) {  
            System.out.println("ScriptEngineFactory Info");  
  
            String engName = factory.getEngineName(); // 引擎名稱  
            String engVersion = factory.getEngineVersion(); // 引擎版本  
            String langName = factory.getLanguageName(); // Script 語言  
            String langVersion = factory.getLanguageVersion(); // 語言版本  
  
            System.out.printf("\tScript Engine: %s (%s)\n", engName, engVersion);  
            List engNames = factory.getNames();  
            for (String name : engNames) {  
                System.out.printf("\t\tEngine Alias: %s\n", name);  
            }  
  
            System.out.printf("\tLanguage: %s (%s)\n", langName, langVersion);  
        }  
    }  
}  

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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package test.scripts;  
  
import java.util.List;  
  
import javax.script.ScriptEngine;  
import javax.script.ScriptEngineFactory;  
import javax.script.ScriptEngineManager;  
  
public class JSDemo3 {  
  
    /** 
     * BD: 範例03：搜尋指定的 Script 引擎 
     * @param args 
     */  
    public static void main(String[] args) {  
        ScriptEngineManager mgr = new ScriptEngineManager();  
        List scriptFactories = mgr.getEngineFactories();  
        for (ScriptEngineFactory factory : scriptFactories) {  
            String langName = factory.getLanguageName();  
            String langVersion = factory.getLanguageVersion();  
            if (langName.startsWith("ECMAScript") && langVersion.startsWith("1.6")) { // 比對指定的與名稱和版本  
                ScriptEngine engine = factory.getScriptEngine();  
                System.out.printf("Engine:%s\n", engine);  
                break;  
            }  
        }  
    }  
}  

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

接著你可以如下執行該 js 檔案:

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package test.scripts;  
  
import java.io.FileInputStream;  
import java.io.InputStream;  
import java.io.InputStreamReader;  
import java.io.Reader;  
  
import javax.script.ScriptEngine;  
import javax.script.ScriptEngineManager;  
import javax.script.ScriptException;  
  
public class JSDemo4 {  
  
    /** 
     * BD: 範例04：執行外部 javasript 檔案 
     * @param args 
     */  
    public static void main(String[] args) throws Exception {  
        ScriptEngineManager engineMgr = new ScriptEngineManager();  
        ScriptEngine engine = engineMgr.getEngineByName("ECMAScript");  
        InputStream is = new FileInputStream("hello.js");  
        try {  
            Reader reader = new InputStreamReader(is);  
            engine.eval(reader);  
        } catch (ScriptException ex) {  
            ex.printStackTrace();  
        }  
    }  
}  

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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package test.scripts;  
  
import javax.script.Invocable;  
import javax.script.ScriptEngine;  
import javax.script.ScriptEngineManager;  
import javax.script.ScriptException;  
  
public class JSDemo5 {  
  
    /** 
     * BD: 範例05：透過 Invocable 介面喚起 Javascript 函數 
     * @param args 
     */  
    public static void main(String[] args) {  
        ScriptEngineManager engineMgr = new ScriptEngineManager();  
        ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
        try {  
            jsEngine.eval("function sayHello() {" +  
                        "  println('Hello, world!');" +  
                        "}");  
            Invocable invocableEngine = (Invocable) jsEngine;  
            invocableEngine.invokeFunction("sayHello");  
        } catch (ScriptException ex) {  
            ex.printStackTrace();  
        } catch (NoSuchMethodException nsme){  
            nsme.printStackTrace();  
        }  
    }  
}  

執行結果:

Hello, world!

範例06：Script 直接存取 Java 物件

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package test.scripts;  
  
import java.util.ArrayList;  
import java.util.List;  
  
import javax.script.ScriptEngine;  
import javax.script.ScriptEngineManager;  
import javax.script.ScriptException;  
  
public class JSDemo6 {  
    /** 
     * BD: 範例06：Script 直接存取 Java 物件  
     * @param args 
     */  
    public static void main(String args[]) {  
        List namesList = new ArrayList();  
        namesList.add("Jill");  
        namesList.add("Bob");  
        namesList.add("Laureen");  
        namesList.add("Ed");  
        ScriptEngineManager engineMgr = new ScriptEngineManager();  
        ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
        jsEngine.put("namesListKey", namesList); // 將 java 變數指定給 javascript 環境中的 nameListKey 變數  
        System.out.println("Executing in script environment…");  
        try {  
            // 列印 Java 的 nameList 變數內容，並新增一個 Dana 字串資料到 List 尾端  
            jsEngine.eval("var x;" + "var names = namesListKey.toArray();"  
                    + "for(x in names) {" + "  println(names[x]);" + "}"  
                    + "namesListKey.add(\"Dana\");");  
        } catch (ScriptException ex) {  
            ex.printStackTrace();  
        }  
        System.out.println("Executing in Java environment…");  
        for (String name : namesList) {  
            System.out.println(name);  
        }  
    }  
}  

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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package test.scripts;  
  
import java.util.ArrayList;  
import java.util.List;  
  
import javax.script.Invocable;  
import javax.script.ScriptEngine;  
import javax.script.ScriptEngineManager;  
import javax.script.ScriptException;  
  
public class JSDemo7 {  
  
    /** 
     * BD: 範例07：透過 Invocable 將參數值傳遞給 Javascript 中的函數 
     * @param args 
     */  
    public static void main(String[] args) {  
        List namesList = new ArrayList();  
        namesList.add("Jill");  
        namesList.add("Bob");  
        namesList.add("Laureen");  
        namesList.add("Ed");  
        ScriptEngineManager engineMgr = new ScriptEngineManager();  
        ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
        Invocable invocableEngine = (Invocable) jsEngine;  
        try {  
            System.out.printf("\t[Info] Execute in JS:\n");  
            jsEngine.eval("function printNames1(namesList) {" + "  var x;"  
                    + "  var names = namesList.toArray();"  
                    + "  for(x in names) {" + "    println(names[x]);" + "  }"  
                    + "}" + "function addName(namesList, name) {"  
                    + "  namesList.add(name);" + "}");  
            invocableEngine.invokeFunction("printNames1", namesList);  
            invocableEngine.invokeFunction("addName", namesList, "Dana");  
            System.out.printf("\t[Info] Execute in Java:\n");  
            for(String name:namesList) System.out.println(name);  
        } catch (ScriptException ex) {  
            ex.printStackTrace();  
        } catch (NoSuchMethodException ex) {  
            ex.printStackTrace();  
        }  
    }  
}  

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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package test.scripts;  
  
import javax.script.ScriptEngine;  
import javax.script.ScriptEngineManager;  
import javax.script.ScriptException;  
  
public class JSDemo8 {  
  
    /** 
     * BD: 範例08：script 使用 Java 的 package 
     * @param args 
     */  
    public static void main(String[] args) {  
        ScriptEngineManager engineMgr = new ScriptEngineManager();  
        ScriptEngine jsEngine = engineMgr.getEngineByName("ECMAScript");  
        try {  
            jsEngine.eval("importPackage(javax.swing);" + "var optionPane = "  
                    + "  JOptionPane.showMessageDialog(null, 'Hello, world!');");  
        } catch (ScriptException ex) {  
            ex.printStackTrace();  
        }  
    }  
}  

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

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2013年9月26日星期四

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

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2013年9月26日 星期四

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

沒有留言:

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[Git 常見問題] error: The following untracked working tree files would be overwritten by merge

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2013年9月26日星期四