javamembers.java

java中比较著名的js引擎当属mozilla开源的rhino

            }
        }

        // Reflect fields.
        Field[] fields = cl.getFields();
        for (int i = 0; i < fields.length; i++) {
            Field field = fields[i];
            int mods = field.getModifiers();
            if (!Modifier.isPublic(mods)) {
                continue;
            }
            boolean isStatic = Modifier.isStatic(mods);
            Hashtable ht = isStatic ? staticMembers : members;
            String name = field.getName();
            Object member = ht.get(name);
            if (member == null) {
                ht.put(name, field);
            } else if (member instanceof NativeJavaMethod) {
                NativeJavaMethod method = (NativeJavaMethod) member;
                FieldAndMethods fam
                    = new FieldAndMethods(scope, method.methods, field);
                Hashtable fmht = isStatic ? staticFieldAndMethods
                                          : fieldAndMethods;
                if (fmht == null) {
                    fmht = new Hashtable(4);
                    if (isStatic) {
                        staticFieldAndMethods = fmht;
                    } else {
                        fieldAndMethods = fmht;
                    }
                }
                fmht.put(name, fam);
                ht.put(name, fam);
            } else if (member instanceof Field) {
                Field oldField = (Field) member;
                // If this newly reflected field shadows an inherited field,
                // then replace it. Otherwise, since access to the field
                // would be ambiguous from Java, no field should be reflected.
                // For now, the first field found wins, unless another field
                // explicitly shadows it.
                if (oldField.getDeclaringClass().
                        isAssignableFrom(field.getDeclaringClass()))
                {
                    ht.put(name, field);
                }
            } else {
                // "unknown member type"
                Kit.codeBug();
            }
        }

        // Create bean propeties from corresponding get/set methods first for
        // static members and then for instance members
        for (int tableCursor = 0; tableCursor != 2; ++tableCursor) {
            boolean isStatic = (tableCursor == 0);
            Hashtable ht = (isStatic) ? staticMembers : members;

            Hashtable toAdd = new Hashtable();

            // Now, For each member, make "bean" properties.
            for (Enumeration e = ht.keys(); e.hasMoreElements(); ) {

                // Is this a getter?
                String name = (String) e.nextElement();
                boolean memberIsGetMethod = name.startsWith("get");
                boolean memberIsSetMethod = name.startsWith("set");
                boolean memberIsIsMethod = name.startsWith("is");
                if (memberIsGetMethod || memberIsIsMethod 
                        || memberIsSetMethod) {
                    // Double check name component.
                    String nameComponent
                        = name.substring(memberIsIsMethod ? 2 : 3);
                    if (nameComponent.length() == 0)
                        continue;

                    // Make the bean property name.
                    String beanPropertyName = nameComponent;
                    char ch0 = nameComponent.charAt(0);
                    if (Character.isUpperCase(ch0)) {
                        if (nameComponent.length() == 1) {
                            beanPropertyName = nameComponent.toLowerCase();
                        } else {
                            char ch1 = nameComponent.charAt(1);
                            if (!Character.isUpperCase(ch1)) {
                                beanPropertyName = Character.toLowerCase(ch0)
                                                   +nameComponent.substring(1);
                            }
                        }
                    }

                    // If we already have a member by this name, don't do this
                    // property.
                    if (ht.containsKey(beanPropertyName)
                            || toAdd.containsKey(beanPropertyName)) {
                        continue;
                    }

                    // Find the getter method, or if there is none, the is-
                    // method.
                    MemberBox getter = null;
                    String getterName = "get".concat(nameComponent);
                    String isName = "is".concat(nameComponent);
                    getter = findGetter(isStatic, ht, getterName);
                    // If there was no valid getter, check for an is- method.
                    if (getter == null) {
                        getter = findGetter(isStatic, ht, isName);
                    }

                    // setter
                    MemberBox setter = null;
                    NativeJavaMethod setters = null;
                    String setterName = "set".concat(nameComponent);

                    if (ht.containsKey(setterName)) {
                        // Is this value a method?
                        Object member = ht.get(setterName);
                        if (member instanceof NativeJavaMethod) {
                            NativeJavaMethod njmSet = (NativeJavaMethod)member;
                            if (getter != null) {
                                // We have a getter. Now, do we have a matching 
                                // setter?
                                Class type = getter.method().getReturnType();
                                setter = extractSetMethod(type, njmSet.methods,
                                                            isStatic);
                            } else {
                                // No getter, find any set method
                                setter = extractSetMethod(njmSet.methods, 
                                                            isStatic);
                            }
                            if (njmSet.methods.length > 1) {
                                setters = njmSet;
                            }
                        }
                    }
                    // Make the property.
                    BeanProperty bp = new BeanProperty(getter, setter,
                                                       setters);
                    toAdd.put(beanPropertyName, bp);
                }
            }

            // Add the new bean properties.
            for (Enumeration e = toAdd.keys(); e.hasMoreElements();) {
                Object key = e.nextElement();
                Object value = toAdd.get(key);
                ht.put(key, value);
            }
        }

        // Reflect constructors
        Constructor[] constructors = cl.getConstructors();
        ctors = new MemberBox[constructors.length];
        for (int i = 0; i != constructors.length; ++i) {
            ctors[i] = new MemberBox(constructors[i]);
        }
    }

    private MemberBox findGetter(boolean isStatic, Hashtable ht, String getterName)
    {
        if (ht.containsKey(getterName)) {
            // Check that the getter is a method.
            Object member = ht.get(getterName);
            if (member instanceof NativeJavaMethod) {
                NativeJavaMethod njmGet = (NativeJavaMethod) member;
                return extractGetMethod(njmGet.methods, isStatic);
            }
        }
        return null;
    }

    private static MemberBox extractGetMethod(MemberBox[] methods,
                                              boolean isStatic)
    {
        // Inspect the list of all MemberBox for the only one having no
        // parameters
        for (int methodIdx = 0; methodIdx < methods.length; methodIdx++) {
            MemberBox method = methods[methodIdx];
            // Does getter method have an empty parameter list with a return
            // value (eg. a getSomething() or isSomething())?
            if (method.argTypes.length == 0
                && (!isStatic || method.isStatic()))
            {
                Class type = method.method().getReturnType();
                if (type != Void.TYPE) {
                    return method;
                }
                break;
            }
        }
        return null;
    }

    private static MemberBox extractSetMethod(Class type, MemberBox[] methods,
                                              boolean isStatic)
    {
        //
        // Note: it may be preferable to allow NativeJavaMethod.findFunction()
        //       to find the appropriate setter; unfortunately, it requires an
        //       instance of the target arg to determine that.
        //

        // Make two passes: one to find a method with direct type assignment,
        // and one to find a widening conversion.
        for (int pass = 1; pass <= 2; ++pass) {
            for (int i = 0; i < methods.length; ++i) {
                MemberBox method = methods[i];
                if (!isStatic || method.isStatic()) {
                    if (method.method().getReturnType() == Void.TYPE) {
                        Class[] params = method.argTypes;
                        if (params.length == 1) {
                            if (pass == 1) {
                                if (params[0] == type) {
                                    return method;
                                }
                            } else {
                                if (pass != 2) Kit.codeBug();
                                if (params[0].isAssignableFrom(type)) {
                                    return method;
                                }
                            }
                        }
                    }
                }
            }
        }
        return null;
    }

    private static MemberBox extractSetMethod(MemberBox[] methods,
                                              boolean isStatic)
    {

        for (int i = 0; i < methods.length; ++i) {
            MemberBox method = methods[i];
            if (!isStatic || method.isStatic()) {
                if (method.method().getReturnType() == Void.TYPE) {
                    if (method.argTypes.length == 1) {
                        return method;
                    }
                }
            }
        }
        return null;
    }

    Hashtable getFieldAndMethodsObjects(Scriptable scope, Object javaObject,
                                        boolean isStatic)
    {
        Hashtable ht = isStatic ? staticFieldAndMethods : fieldAndMethods;
        if (ht == null)
            return null;
        int len = ht.size();
        Hashtable result = new Hashtable(len);
        Enumeration e = ht.elements();
        while (len-- > 0) {
            FieldAndMethods fam = (FieldAndMethods) e.nextElement();
            FieldAndMethods famNew = new FieldAndMethods(scope, fam.methods,
                                                         fam.field);
            famNew.javaObject = javaObject;
            result.put(fam.field.getName(), famNew);
        }
        return result;
    }

    static JavaMembers lookupClass(Scriptable scope, Class dynamicType,
                                   Class staticType)
    {
        JavaMembers members;
        ClassCache cache = ClassCache.get(scope);
        Hashtable ct = cache.classTable;

        Class cl = dynamicType;
        for (;;) {
            members = (JavaMembers)ct.get(cl);
            if (members != null) {
                return members;
            }
            try {
                members = new JavaMembers(cache.scope, cl);
                break;
            } catch (SecurityException e) {
                // Reflection may fail for objects that are in a restricted
                // access package (e.g. sun.*).  If we get a security
                // exception, try again with the static type if it is interface.
                // Otherwise, try superclass
                if (staticType != null && staticType.isInterface()) {
                    cl = staticType;
                    staticType = null; // try staticType only once
                } else {
                    Class parent = cl.getSuperclass();
                    if (parent == null) {
                        if (cl.isInterface()) {
                            // last resort after failed staticType interface
                            parent = ScriptRuntime.ObjectClass;
                        } else {
                            throw e;
                        }
                    }
                    cl = parent;
                }
            }
        }

        if (cache.isCachingEnabled())
            ct.put(cl, members);
        return members;
    }

    RuntimeException reportMemberNotFound(String memberName)
    {
        return Context.reportRuntimeError2(
            "msg.java.member.not.found", cl.getName(), memberName);
    }

    private Class cl;
    private Hashtable members;
    private Hashtable fieldAndMethods;
    private Hashtable staticMembers;
    private Hashtable staticFieldAndMethods;
    MemberBox[] ctors;
}

class BeanProperty
{
    BeanProperty(MemberBox getter, MemberBox setter, NativeJavaMethod setters)
    {
        this.getter = getter;
        this.setter = setter;
        this.setters = setters;
    }

    MemberBox getter;
    MemberBox setter;
    NativeJavaMethod setters;
}

class FieldAndMethods extends NativeJavaMethod
{
    static final long serialVersionUID = -9222428244284796755L;

    FieldAndMethods(Scriptable scope, MemberBox[] methods, Field field)
    {
        super(methods);
        this.field = field;
        setParentScope(scope);
        setPrototype(ScriptableObject.getFunctionPrototype(scope));
    }

    public Object getDefaultValue(Class hint)
    {
        if (hint == ScriptRuntime.FunctionClass)
            return this;
        Object rval;
        Class type;
        try {
            rval = field.get(javaObject);
            type = field.getType();
        } catch (IllegalAccessException accEx) {
            throw Context.reportRuntimeError1(
                "msg.java.internal.private", field.getName());
        }
        Context cx  = Context.getContext();
        rval = cx.getWrapFactory().wrap(cx, this, rval, type);
        if (rval instanceof Scriptable) {
            rval = ((Scriptable) rval).getDefaultValue(hint);
        }
        return rval;
    }

    Field field;
    Object javaObject;
}