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Java Language Оценка файла javascript в режиме -scripting nashorn


пример

public class JSEngine {
    
    /*
    * Note Nashorn is only available for Java-8 onwards
    * You can use rhino from ScriptEngineManager.getEngineByName("js");
    */
    
    ScriptEngine engine;
    ScriptContext context;
    public Bindings scope;
    
    // Initialize the Engine from its factory in scripting mode
    public JSEngine(){
        engine = new NashornScriptEngineFactory().getScriptEngine("-scripting");
        // Script context is an interface so we need an implementation of it
        context = new SimpleScriptContext();
        // Create bindings to expose variables into
        scope = engine.createBindings();
    }
    
    // Clear the bindings to remove the previous variables
    public void newBatch(){
        scope.clear();
    }
    
    public void execute(String file){
        try {
            // Get a buffered reader for input
            BufferedReader br = new BufferedReader(new FileReader(file));
            // Evaluate code, with input as bufferdReader
            engine.eval(br);
        } catch (FileNotFoundException ex) {
            Logger.getLogger(JSEngine.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ScriptException ex) {
            // Script Exception is basically when there is an error in script
            Logger.getLogger(JSEngine.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    
    public void eval(String code){
        try {
            // Engine.eval basically treats any string as a line of code and evaluates it, executes it
            engine.eval(code);
        } catch (ScriptException ex) {
            // Script Exception is basically when there is an error in script
            Logger.getLogger(JSEngine.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    
    // Apply the bindings to the context and set the engine's default context
    public void startBatch(int SCP){
        context.setBindings(scope, SCP);
        engine.setContext(context);
    }
    
    // We use the invocable interface to access methods from the script
    // Invocable is an optional interface, please check if your engine implements it
    public Invocable invocable(){
        return (Invocable)engine;
    }
    
}

Теперь основной метод

public static void main(String[] args) {
    JSEngine jse = new JSEngine();
    // Create a new batch probably unecessary
    jse.newBatch();
    // Expose variable x into script with value of hello world
    jse.scope.put("x", "hello world");
    // Apply the bindings and start the batch
    jse.startBatch(ScriptContext.ENGINE_SCOPE);
    // Evaluate the code
    jse.eval("print(x);");
}

Ваш результат должен быть похож на этот
hello world

Как вы видите, открытая переменная x была напечатана. Теперь тестирование с помощью файла.

Здесь у нас есть test.js

print(x);
function test(){
    print("hello test.js:test");
}
test();

И обновленный основной метод

public static void main(String[] args) {
    JSEngine jse = new JSEngine();
    // Create a new batch probably unecessary
    jse.newBatch();
    // Expose variable x into script with value of hello world
    jse.scope.put("x", "hello world");
    // Apply the bindings and start the batch
    jse.startBatch(ScriptContext.ENGINE_SCOPE);
    // Evaluate the code
    jse.execute("./test.js");
}

Предполагая, что test.js находится в том же каталоге, что и ваше приложение, вы должны иметь аналогичный результат

hello world
hello test.js:test