Java example source code file (JObjCRuntime.java)

This example Java source code file (JObjCRuntime.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arch, class, did, is64, is_big_endian, jobjcruntime, nativeargumentbuffer, nio, ptr_len, reflection, runtimeexception, string, subclassing, unsafe, util, w32, width

The JObjCRuntime.java Java example source code

/*
 * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.apple.jobjc;

import java.lang.reflect.Field;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.List;

import sun.misc.Unsafe;


public final class JObjCRuntime {
    static { System.loadLibrary("JObjC"); }

    public static enum Arch{ ppc, i386, x86_64 };
    public static enum Width{ W32, W64 };

    public static final Arch ARCH = getArch();
    public static final Width WIDTH = getWidth();

    private static Arch getArch(){
        String arch = System.getProperty("os.arch");
        if("ppc".equals(arch)) return Arch.ppc;
        if("i386".equals(arch)) return Arch.i386;
        if("x86_64".equals(arch)) return Arch.x86_64;
        if("amd64".equals(arch)) return Arch.x86_64;
        if("universal".equals(arch)) return Arch.x86_64;
        throw new RuntimeException("Did not recognize os.arch system property: '" + arch + "'");
    }

    private static Width getWidth(){
        String width = System.getProperty("sun.arch.data.model");
        if("32".equals(width)) return Width.W32;
        if("64".equals(width)) return Width.W64;
        throw new RuntimeException("Did not recognize sun.arch.data.model system property: '" + width + "'");
    }

    public static final boolean IS32 = System.getProperty("sun.arch.data.model").equals("32");
    public static final boolean IS64 = System.getProperty("sun.arch.data.model").equals("64");
    public static final int PTR_LEN = IS64 ? 8 : 4;
    public static final boolean IS_BIG_ENDIAN = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN;
    static final boolean DEBUG = Boolean.parseBoolean(System.getProperty("JObjC.debug"));

    static void checkPermission(){
        final SecurityManager security = System.getSecurityManager();
        if (security != null) security.checkPermission(new RuntimePermission("canProcessApplicationEvents"));
    }

    public final void assertOK(){
        if(this != instance)
            throw new SecurityException("runtime");
    }

    private JObjCRuntime(){}

    private static JObjCRuntime instance;
    static JObjCRuntime inst() {
        if (instance == null) instance = new JObjCRuntime();
        return instance;
    }

    public static JObjCRuntime getInstance() {
        checkPermission();
        return inst();
    }

    public final NativeArgumentBuffer getThreadLocalState() {
        return NativeArgumentBuffer.getThreadLocalBuffer(this);
    }

    final Unsafe unsafe = getUnsafe();
    final Subclassing subclassing = new Subclassing(this);
    final List<String> registeredPackages = new ArrayList();

    @SuppressWarnings("unchecked")
    Class<? extends ID> getClassForNativeClassName(final String className) {
        for (final String pkg : registeredPackages) {
            try {
                final Class<?> clazz = Class.forName(pkg + "." + className);
                if (clazz != null) return (Class<? extends ID>)clazz;
            } catch (final ClassNotFoundException e) { }
        }

        return null;
    }

    private final static Unsafe getUnsafe() {
        Unsafe inst = null;
        try {
            Field f = Unsafe.class.getDeclaredField("theUnsafe");
            f.setAccessible(true);
            inst = (Unsafe) f.get(null);
            if(inst == null) throw new NullPointerException("Unsafe.theUnsafe == null");
        } catch (Exception e) {
            throw new RuntimeException("Unable to get instance of Unsafe.", e);
        }
        return inst;
    }

    public void registerPackage(final String pkg) {
        registeredPackages.add(pkg);
    }

    /**
     * Register a subclass of NSObject to allow the native side to send
     * messages which in turn call java methods declared on the class.
     * If a native class by the same name already exists, registerClass
     * will simply return without doing anything.
     *
     * For a usage example, see the SubclassingTest.
     */
    public boolean registerUserClass(Class<? extends ID> clazz, Class clazzClazz) {
        return subclassing.registerUserClass(clazz, clazzClazz);
    }

}