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Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically
embedded into Java applications to provide scripting to end users.
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.javascript;
import java.lang.reflect.*;
import java.util.Map;
/**
* This class reflects Java classes into the JavaScript environment, mainly
* for constructors and static members. We lazily reflect properties,
* and currently do not guarantee that a single j.l.Class is only
* reflected once into the JS environment, although we should.
* The only known case where multiple reflections
* are possible occurs when a j.l.Class is wrapped as part of a
* method return or property access, rather than by walking the
* Packages/java tree.
*
* @author Mike Shaver
* @see NativeJavaArray
* @see NativeJavaObject
* @see NativeJavaPackage
*/
public class NativeJavaClass extends NativeJavaObject implements Function
{
static final long serialVersionUID = -6460763940409461664L;
// Special property for getting the underlying Java class object.
static final String javaClassPropertyName = "__javaObject__";
public NativeJavaClass() {
}
public NativeJavaClass(Scriptable scope, Class cl) {
this(scope, cl, false);
}
public NativeJavaClass(Scriptable scope, Class cl, boolean isAdapter) {
super(scope, cl, null, isAdapter);
}
@Override
protected void initMembers() {
Class cl = (Class)javaObject;
members = JavaMembers.lookupClass(parent, cl, cl, isAdapter);
staticFieldAndMethods = members.getFieldAndMethodsObjects(this, cl, true);
}
@Override
public String getClassName() {
return "JavaClass";
}
@Override
public boolean has(String name, Scriptable start) {
return members.has(name, true) || javaClassPropertyName.equals(name);
}
@Override
public Object get(String name, Scriptable start) {
// When used as a constructor, ScriptRuntime.newObject() asks
// for our prototype to create an object of the correct type.
// We don't really care what the object is, since we're returning
// one constructed out of whole cloth, so we return null.
if (name.equals("prototype"))
return null;
if (staticFieldAndMethods != null) {
Object result = staticFieldAndMethods.get(name);
if (result != null)
return result;
}
if (members.has(name, true)) {
return members.get(this, name, javaObject, true);
}
Context cx = Context.getContext();
Scriptable scope = ScriptableObject.getTopLevelScope(start);
WrapFactory wrapFactory = cx.getWrapFactory();
if (javaClassPropertyName.equals(name)) {
return wrapFactory.wrap(cx, scope, javaObject,
ScriptRuntime.ClassClass);
}
// experimental: look for nested classes by appending $name to
// current class' name.
Class nestedClass = findNestedClass(getClassObject(), name);
if (nestedClass != null) {
Scriptable nestedValue = wrapFactory.wrapJavaClass(cx, scope,
nestedClass);
nestedValue.setParentScope(this);
return nestedValue;
}
throw members.reportMemberNotFound(name);
}
@Override
public void put(String name, Scriptable start, Object value) {
members.put(this, name, javaObject, value, true);
}
@Override
public Object[] getIds() {
return members.getIds(true);
}
public Class getClassObject() {
return (Class) super.unwrap();
}
@Override
public Object getDefaultValue(Class hint) {
if (hint == null || hint == ScriptRuntime.StringClass)
return this.toString();
if (hint == ScriptRuntime.BooleanClass)
return Boolean.TRUE;
if (hint == ScriptRuntime.NumberClass)
return ScriptRuntime.NaNobj;
return this;
}
public Object call(Context cx, Scriptable scope, Scriptable thisObj,
Object[] args)
{
// If it looks like a "cast" of an object to this class type,
// walk the prototype chain to see if there's a wrapper of a
// object that's an instanceof this class.
if (args.length == 1 && args[0] instanceof Scriptable) {
Class c = getClassObject();
Scriptable p = (Scriptable) args[0];
do {
if (p instanceof Wrapper) {
Object o = ((Wrapper) p).unwrap();
if (c.isInstance(o))
return p;
}
p = p.getPrototype();
} while (p != null);
}
return construct(cx, scope, args);
}
public Scriptable construct(Context cx, Scriptable scope, Object[] args)
{
Class classObject = getClassObject();
int modifiers = classObject.getModifiers();
if (! (Modifier.isInterface(modifiers) ||
Modifier.isAbstract(modifiers)))
{
NativeJavaMethod ctors = members.ctors;
int index = ctors.findCachedFunction(cx, args);
if (index < 0) {
String sig = NativeJavaMethod.scriptSignature(args);
throw Context.reportRuntimeError2(
"msg.no.java.ctor", classObject.getName(), sig);
}
// Found the constructor, so try invoking it.
return constructSpecific(cx, scope, args, ctors.methods[index]);
} else {
if (args.length == 0) {
throw Context.reportRuntimeError0("msg.adapter.zero.args");
}
Scriptable topLevel = ScriptableObject.getTopLevelScope(this);
String msg = "";
try {
// When running on Android create an InterfaceAdapter since our
// bytecode generation won't work on Dalvik VM.
if ("Dalvik".equals(System.getProperty("java.vm.name"))
&& classObject.isInterface()) {
Object obj = createInterfaceAdapter(classObject,
ScriptableObject.ensureScriptableObject(args[0]));
return cx.getWrapFactory().wrapAsJavaObject(cx, scope, obj, null);
}
// use JavaAdapter to construct a new class on the fly that
// implements/extends this interface/abstract class.
Object v = topLevel.get("JavaAdapter", topLevel);
if (v != NOT_FOUND) {
Function f = (Function) v;
// Args are (interface, js object)
Object[] adapterArgs = { this, args[0] };
return f.construct(cx, topLevel, adapterArgs);
}
} catch (Exception ex) {
// fall through to error
String m = ex.getMessage();
if (m != null)
msg = m;
}
throw Context.reportRuntimeError2(
"msg.cant.instantiate", msg, classObject.getName());
}
}
static Scriptable constructSpecific(Context cx, Scriptable scope,
Object[] args, MemberBox ctor)
{
Object instance = constructInternal(args, ctor);
// we need to force this to be wrapped, because construct _has_
// to return a scriptable
Scriptable topLevel = ScriptableObject.getTopLevelScope(scope);
return cx.getWrapFactory().wrapNewObject(cx, topLevel, instance);
}
static Object constructInternal(Object[] args, MemberBox ctor)
{
Class[] argTypes = ctor.argTypes;
if (ctor.vararg) {
// marshall the explicit parameter
Object[] newArgs = new Object[argTypes.length];
for (int i = 0; i < argTypes.length-1; i++) {
newArgs[i] = Context.jsToJava(args[i], argTypes[i]);
}
Object varArgs;
// Handle special situation where a single variable parameter
// is given and it is a Java or ECMA array.
if (args.length == argTypes.length &&
(args[args.length-1] == null ||
args[args.length-1] instanceof NativeArray ||
args[args.length-1] instanceof NativeJavaArray))
{
// convert the ECMA array into a native array
varArgs = Context.jsToJava(args[args.length-1],
argTypes[argTypes.length - 1]);
} else {
// marshall the variable parameter
Class componentType = argTypes[argTypes.length - 1].
getComponentType();
varArgs = Array.newInstance(componentType,
args.length - argTypes.length + 1);
for (int i=0; i < Array.getLength(varArgs); i++) {
Object value = Context.jsToJava(args[argTypes.length-1 + i],
componentType);
Array.set(varArgs, i, value);
}
}
// add varargs
newArgs[argTypes.length-1] = varArgs;
// replace the original args with the new one
args = newArgs;
} else {
Object[] origArgs = args;
for (int i = 0; i < args.length; i++) {
Object arg = args[i];
Object x = Context.jsToJava(arg, argTypes[i]);
if (x != arg) {
if (args == origArgs) {
args = origArgs.clone();
}
args[i] = x;
}
}
}
return ctor.newInstance(args);
}
@Override
public String toString() {
return "[JavaClass " + getClassObject().getName() + "]";
}
/**
* Determines if prototype is a wrapped Java object and performs
* a Java "instanceof".
* Exception: if value is an instance of NativeJavaClass, it isn't
* considered an instance of the Java class; this forestalls any
* name conflicts between java.lang.Class's methods and the
* static methods exposed by a JavaNativeClass.
*/
@Override
public boolean hasInstance(Scriptable value) {
if (value instanceof Wrapper &&
!(value instanceof NativeJavaClass)) {
Object instance = ((Wrapper)value).unwrap();
return getClassObject().isInstance(instance);
}
// value wasn't something we understand
return false;
}
private static Class findNestedClass(Class parentClass, String name) {
String nestedClassName = parentClass.getName() + '$' + name;
ClassLoader loader = parentClass.getClassLoader();
if (loader == null) {
// ALERT: if loader is null, nested class should be loaded
// via system class loader which can be different from the
// loader that brought Rhino classes that Class.forName() would
// use, but ClassLoader.getSystemClassLoader() is Java 2 only
return Kit.classOrNull(nestedClassName);
} else {
return Kit.classOrNull(loader, nestedClassName);
}
}
private Map staticFieldAndMethods;
}
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