scriptableobject.java

java中比较著名的js引擎当属mozilla开源的rhino

     * to define the JavaScript constructor. If the class has three
     * or more constructors, an {@link EvaluatorException}
     * will be thrown.<p>
     *
     * Finally, if there is a method
     * <pre>
     * static void finishInit(Scriptable scope, FunctionObject constructor,
     *                        Scriptable prototype)</pre>
     *
     * it will be called to finish any initialization. The <code>scope</code>
     * argument will be passed, along with the newly created constructor and
     * the newly created prototype.<p>
     *
     * @param scope The scope in which to define the constructor.
     * @param clazz The Java class to use to define the JavaScript objects
     *              and properties.
     * @exception IllegalAccessException if access is not available
     *            to a reflected class member
     * @exception InstantiationException if unable to instantiate
     *            the named class
     * @exception InvocationTargetException if an exception is thrown
     *            during execution of methods of the named class
     * @see org.mozilla.javascript.Function
     * @see org.mozilla.javascript.FunctionObject
     * @see org.mozilla.javascript.ScriptableObject#READONLY
     * @see org.mozilla.javascript.ScriptableObject#defineProperty
     */
    public static void defineClass(Scriptable scope, Class clazz)
        throws IllegalAccessException, InstantiationException,
               InvocationTargetException
    {
        defineClass(scope, clazz, false, false);
    }

    /**
     * Defines JavaScript objects from a Java class, optionally
     * allowing sealing.
     *
     * Similar to <code>defineClass(Scriptable scope, Class clazz)</code>
     * except that sealing is allowed. An object that is sealed cannot have
     * properties added or removed. Note that sealing is not allowed in
     * the current ECMA/ISO language specification, but is likely for
     * the next version.
     *
     * @param scope The scope in which to define the constructor.
     * @param clazz The Java class to use to define the JavaScript objects
     *              and properties. The class must implement Scriptable.
     * @param sealed Whether or not to create sealed standard objects that
     *               cannot be modified.
     * @exception IllegalAccessException if access is not available
     *            to a reflected class member
     * @exception InstantiationException if unable to instantiate
     *            the named class
     * @exception InvocationTargetException if an exception is thrown
     *            during execution of methods of the named class
     * @since 1.4R3
     */
    public static void defineClass(Scriptable scope, Class clazz,
                                   boolean sealed)
        throws IllegalAccessException, InstantiationException,
               InvocationTargetException
    {
        defineClass(scope, clazz, sealed, false);
    }

    /**
     * Defines JavaScript objects from a Java class, optionally
     * allowing sealing and mapping of Java inheritance to JavaScript
     * prototype-based inheritance.
     *
     * Similar to <code>defineClass(Scriptable scope, Class clazz)</code>
     * except that sealing and inheritance mapping are allowed. An object
     * that is sealed cannot have properties added or removed. Note that
     * sealing is not allowed in the current ECMA/ISO language specification,
     * but is likely for the next version.
     *
     * @param scope The scope in which to define the constructor.
     * @param clazz The Java class to use to define the JavaScript objects
     *              and properties. The class must implement Scriptable.
     * @param sealed Whether or not to create sealed standard objects that
     *               cannot be modified.
     * @param mapInheritance Whether or not to map Java inheritance to
     *                       JavaScript prototype-based inheritance.
     * @return the class name for the prototype of the specified class
     * @exception IllegalAccessException if access is not available
     *            to a reflected class member
     * @exception InstantiationException if unable to instantiate
     *            the named class
     * @exception InvocationTargetException if an exception is thrown
     *            during execution of methods of the named class
     * @since 1.6R2
     */
    public static String defineClass(Scriptable scope, Class clazz,
                                   boolean sealed, boolean mapInheritance)
        throws IllegalAccessException, InstantiationException,
               InvocationTargetException
    {
        Method[] methods = FunctionObject.getMethodList(clazz);
        for (int i=0; i < methods.length; i++) {
            Method method = methods[i];
            if (!method.getName().equals("init"))
                continue;
            Class[] parmTypes = method.getParameterTypes();
            if (parmTypes.length == 3 &&
                parmTypes[0] == ScriptRuntime.ContextClass &&
                parmTypes[1] == ScriptRuntime.ScriptableClass &&
                parmTypes[2] == Boolean.TYPE &&
                Modifier.isStatic(method.getModifiers()))
            {
                Object args[] = { Context.getContext(), scope,
                                  sealed ? Boolean.TRUE : Boolean.FALSE };
                method.invoke(null, args);
                return null;
            }
            if (parmTypes.length == 1 &&
                parmTypes[0] == ScriptRuntime.ScriptableClass &&
                Modifier.isStatic(method.getModifiers()))
            {
                Object args[] = { scope };
                method.invoke(null, args);
                return null;
            }

        }

        // If we got here, there isn't an "init" method with the right
        // parameter types.

        Constructor[] ctors = clazz.getConstructors();
        Constructor protoCtor = null;
        for (int i=0; i < ctors.length; i++) {
            if (ctors[i].getParameterTypes().length == 0) {
                protoCtor = ctors[i];
                break;
            }
        }
        if (protoCtor == null) {
            throw Context.reportRuntimeError1(
                      "msg.zero.arg.ctor", clazz.getName());
        }

        Scriptable proto = (Scriptable) protoCtor.newInstance(ScriptRuntime.emptyArgs);
        String className = proto.getClassName();

        // Set the prototype's prototype, trying to map Java inheritance to JS
        // prototype-based inheritance if requested to do so.
        Scriptable superProto = null;
        if (mapInheritance) {
            Class superClass = clazz.getSuperclass();
            if (ScriptRuntime.ScriptableClass.isAssignableFrom(superClass)) {
                String name = ScriptableObject.defineClass(scope, superClass, sealed, mapInheritance);
                if (name != null) {
                    superProto = ScriptableObject.getClassPrototype(scope, name);
                }
            }
        }
        if (superProto == null) {
            superProto = ScriptableObject.getObjectPrototype(scope);
        }
        proto.setPrototype(superProto);

        // Find out whether there are any methods that begin with
        // "js". If so, then only methods that begin with special
        // prefixes will be defined as JavaScript entities.
        final String functionPrefix = "jsFunction_";
        final String staticFunctionPrefix = "jsStaticFunction_";
        final String getterPrefix = "jsGet_";
        final String setterPrefix = "jsSet_";
        final String ctorName = "jsConstructor";

        Member ctorMember = FunctionObject.findSingleMethod(methods, ctorName);

        if (ctorMember == null) {
            if (ctors.length == 1) {
                ctorMember = ctors[0];
            } else if (ctors.length == 2) {
                if (ctors[0].getParameterTypes().length == 0)
                    ctorMember = ctors[1];
                else if (ctors[1].getParameterTypes().length == 0)
                    ctorMember = ctors[0];
            }
            if (ctorMember == null) {
                throw Context.reportRuntimeError1(
                          "msg.ctor.multiple.parms", clazz.getName());
            }
        }

        FunctionObject ctor = new FunctionObject(className, ctorMember, scope);
        if (ctor.isVarArgsMethod()) {
            throw Context.reportRuntimeError1
                ("msg.varargs.ctor", ctorMember.getName());
        }
        ctor.addAsConstructor(scope, proto);

        Method finishInit = null;
        for (int i=0; i < methods.length; i++) {
            if (methods[i] == ctorMember) {
                continue;
            }
            String name = methods[i].getName();
            if (name.equals("finishInit")) {
                Class[] parmTypes = methods[i].getParameterTypes();
                if (parmTypes.length == 3 &&
                    parmTypes[0] == ScriptRuntime.ScriptableClass &&
                    parmTypes[1] == FunctionObject.class &&
                    parmTypes[2] == ScriptRuntime.ScriptableClass &&
                    Modifier.isStatic(methods[i].getModifiers()))
                {
                    finishInit = methods[i];
                    continue;
                }
            }
            // ignore any compiler generated methods.
            if (name.indexOf('$') != -1)
                continue;
            if (name.equals(ctorName))
                continue;

            String prefix = null;
            if (name.startsWith(functionPrefix)) {
                prefix = functionPrefix;
            } else if (name.startsWith(staticFunctionPrefix)) {
                prefix = staticFunctionPrefix;
                if (!Modifier.isStatic(methods[i].getModifiers())) {
                    throw Context.reportRuntimeError(
                        "jsStaticFunction must be used with static method.");
                }
            } else if (name.startsWith(getterPrefix)) {
                prefix = getterPrefix;
            } else if (name.startsWith(setterPrefix)) {
                prefix = setterPrefix;
            } else {
                continue;
            }
            name = name.substring(prefix.length());
            if (prefix == setterPrefix)
                continue;   // deal with set when we see get
            if (prefix == getterPrefix) {
                if (!(proto instanceof ScriptableObject)) {
                    throw Context.reportRuntimeError2(
                        "msg.extend.scriptable",
                        proto.getClass().toString(), name);
                }
                Method setter = FunctionObject.findSingleMethod(
                                    methods,
                                    setterPrefix + name);
                int attr = ScriptableObject.PERMANENT |
                           ScriptableObject.DONTENUM  |
                           (setter != null ? 0
                                           : ScriptableObject.READONLY);
                ((ScriptableObject) proto).defineProperty(name, null,
                                                          methods[i], setter,
                                                          attr);
                continue;
            }

            FunctionObject f = new FunctionObject(name, methods[i], proto);
            if (f.isVarArgsConstructor()) {
                throw Context.reportRuntimeError1
                    ("msg.varargs.fun", ctorMember.getName());
            }
            Scriptable dest = prefix == staticFunctionPrefix
                              ? ctor
                              : proto;
            defineProperty(dest, name, f, DONTENUM);
            if (sealed) {
                f.sealObject();
            }
        }

        // Call user code to complete initialization if necessary.
        if (finishInit != null) {
            Object[] finishArgs = { scope, ctor, proto };
            finishInit.invoke(null, finishArgs);
        }

        // Seal the object if necessary.
        if (sealed) {
            ctor.sealObject();
            if (proto instanceof ScriptableObject) {
                ((ScriptableObject) proto).sealObject();
            }
        }

        return className;
    }

    /**
     * Define a JavaScript property.
     *
     * Creates the property with an initial value and sets its attributes.
     *
     * @param propertyName the name of the property to define.
     * @param value the initial value of the property
     * @param attributes the attributes of the JavaScript property
     * @see org.mozilla.javascript.Scriptable#put
     */
    public void defineProperty(String propertyName, Object value,
                               int attributes)
    {
        put(propertyName, this, value);
        setAttributes(propertyName, attributes);
    }

    /**
     * Utility method to add properties to arbitrary Scriptable object.
     * If destination is instance of ScriptableObject, calls
     * defineProperty there, otherwise calls put in destination
     * ignoring attributes
     */
    public static void defineProperty(Scriptable destination,
                                      String propertyName, Object value,
                                      int attributes)
    {
        if (!(destination instanceof ScriptableObject)) {
            destination.put(propertyName, destination, value);
            return;
        }
        ScriptableObject so = (ScriptableObject)destination;
        so.defineProperty(propertyName, value, attributes);
    }

    /**
     * Define a JavaScript property with getter and setter side effects.
     *
     * If the setter is not found, the attribute READONLY is added to
     * the given attributes. <p>
     *
     * The getter must be a method with zero parameters, and the setter, if
     * found, must be a method with one parameter.<p>
     *
     * @param propertyName the name of the property to define. This name
     *                    also affects the name of the setter and getter
     *                    to search for. If the propertyId is "foo", then
     *                    <code>clazz</code> will be searched for "getFoo"
     *                    and "setFoo" methods.
     * @param clazz the Java class to search for the getter and setter
     * @param attributes the attributes of the JavaScript property
     * @see org.mozilla.javascript.Scriptable#put
     */
    public void defineProperty(String propertyName, Class clazz,
                               int attributes)
    {
        int length = propertyName.length();
        if (length == 0) throw new IllegalArgumentException();
        char[] buf = new char[3 + length];
        propertyName.getChars(0, length, buf, 3);
        buf[3] = Character.toUpperCase(buf[3]);
        buf[0] = 'g';
        buf[1] = 'e';
        buf[2] = 't';