/*
 * Copyright (c) 2005, 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 sun.reflect.misc;

import java.io.EOFException;
import java.security.AllPermission;
import java.security.AccessController;
import java.security.PermissionCollection;
import java.security.SecureClassLoader;
import java.security.PrivilegedExceptionAction;
import java.security.CodeSource;
import java.io.InputStream;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;

import sun.misc.IOUtils;

class Trampoline {
    static {
        if (Trampoline.class.getClassLoader() == null) {
            throw new Error(
                "Trampoline must not be defined by the bootstrap classloader");
        }
    }

    private static void ensureInvocableMethod(Method m)
        throws InvocationTargetException
    {
        Class<?> clazz = m.getDeclaringClass();
        if (clazz.equals(AccessController.class) ||
            clazz.equals(Method.class) ||
            clazz.getName().startsWith("java.lang.invoke."))
            throw new InvocationTargetException(
                new UnsupportedOperationException("invocation not supported"));
    }

    private static Object invoke(Method m, Object obj, Object[] params)
        throws InvocationTargetException, IllegalAccessException
    {
        ensureInvocableMethod(m);
        return m.invoke(obj, params);
    }
}

/*
 * Create a trampoline class.
 */
public final class MethodUtil extends SecureClassLoader {
    private static final String MISC_PKG = "sun.reflect.misc.";
    private static final String TRAMPOLINE = MISC_PKG + "Trampoline";
    private static final Method bounce = getTrampoline();

    private MethodUtil() {
        super();
    }

    public static Method getMethod(Class<?> cls, String name, Class<?>[] args)
        throws NoSuchMethodException {
        ReflectUtil.checkPackageAccess(cls);
        return cls.getMethod(name, args);
    }

    public static Method[] getMethods(Class<?> cls) {
        ReflectUtil.checkPackageAccess(cls);
        return cls.getMethods();
    }

    /*
     * Discover the public methods on public classes
     * and interfaces accessible to any caller by calling
     * Class.getMethods() and walking towards Object until
     * we're done.
     */
     public static Method[] getPublicMethods(Class<?> cls) {
        // compatibility for update release
        if (System.getSecurityManager() == null) {
            return cls.getMethods();
        }
        Map<Signature, Method> sigs = new HashMap<Signature, Method>();
        while (cls != null) {
            boolean done = getInternalPublicMethods(cls, sigs);
            if (done) {
                break;
            }
            getInterfaceMethods(cls, sigs);
            cls = cls.getSuperclass();
        }
        return sigs.values().toArray(new Method[sigs.size()]);
    }

    /*
     * Process the immediate interfaces of this class or interface.
     */
    private static void getInterfaceMethods(Class<?> cls,
                                            Map<Signature, Method> sigs) {
        Class<?>[] intfs = cls.getInterfaces();
        for (int i=0; i < intfs.length; i++) {
            Class<?> intf = intfs[i];
            boolean done = getInternalPublicMethods(intf, sigs);
            if (!done) {
                getInterfaceMethods(intf, sigs);
            }
        }
    }

    /*
     *
     * Process the methods in this class or interface
     */
    private static boolean getInternalPublicMethods(Class<?> cls,
                                                    Map<Signature, Method> sigs) {
        Method[] methods = null;
        try {
            /*
             * This class or interface is non-public so we
             * can't use any of it's methods. Go back and
             * try again with a superclass or superinterface.
             */
            if (!Modifier.isPublic(cls.getModifiers())) {
                return false;
            }
            if (!ReflectUtil.isPackageAccessible(cls)) {
                return false;
            }

            methods = cls.getMethods();
        } catch (SecurityException se) {
            return false;
        }

        /*
         * Check for inherited methods with non-public
         * declaring classes. They might override and hide
         * methods from their superclasses or
         * superinterfaces.
         */
        boolean done = true;
        for (int i=0; i < methods.length; i++) {
            Class<?> dc = methods[i].getDeclaringClass();
            if (!Modifier.isPublic(dc.getModifiers())) {
                done = false;
                break;
            }
        }

        if (done) {
            /*
             * We're done. Spray all the methods into
             * the list and then we're out of here.
             */
            for (int i=0; i < methods.length; i++) {
                addMethod(sigs, methods[i]);
            }
        } else {
            /*
             * Simulate cls.getDeclaredMethods() by
             * stripping away inherited methods.
             */
            for (int i=0; i < methods.length; i++) {
                Class<?> dc = methods[i].getDeclaringClass();
                if (cls.equals(dc)) {
                    addMethod(sigs, methods[i]);
                }
            }
        }
        return done;
    }

    private static void addMethod(Map<Signature, Method> sigs, Method method) {
        Signature signature = new Signature(method);
        if (!sigs.containsKey(signature)) {
            sigs.put(signature, method);
        } else if (!method.getDeclaringClass().isInterface()){
            /*
             * Superclasses beat interfaces.
             */
            Method old = sigs.get(signature);
            if (old.getDeclaringClass().isInterface()) {
                sigs.put(signature, method);
            }
        }
    }

    
A class that represents the unique elements of a method that will be a key in the method cache.
/** * A class that represents the unique elements of a method that will be a * key in the method cache. */
private static class Signature { private String methodName; private Class<?>[] argClasses; private volatile int hashCode = 0; Signature(Method m) { this.methodName = m.getName(); this.argClasses = m.getParameterTypes(); } public boolean equals(Object o2) { if (this == o2) { return true; } Signature that = (Signature)o2; if (!(methodName.equals(that.methodName))) { return false; } if (argClasses.length != that.argClasses.length) { return false; } for (int i = 0; i < argClasses.length; i++) { if (!(argClasses[i] == that.argClasses[i])) { return false; } } return true; }
Hash code computed using algorithm suggested in Effective Java, Item 8.
/** * Hash code computed using algorithm suggested in * Effective Java, Item 8. */
public int hashCode() { if (hashCode == 0) { int result = 17; result = 37 * result + methodName.hashCode(); if (argClasses != null) { for (int i = 0; i < argClasses.length; i++) { result = 37 * result + ((argClasses[i] == null) ? 0 : argClasses[i].hashCode()); } } hashCode = result; } return hashCode; } } /* * Bounce through the trampoline. */ public static Object invoke(Method m, Object obj, Object[] params) throws InvocationTargetException, IllegalAccessException { try { return bounce.invoke(null, new Object[] {m, obj, params}); } catch (InvocationTargetException ie) { Throwable t = ie.getCause(); if (t instanceof InvocationTargetException) { throw (InvocationTargetException)t; } else if (t instanceof IllegalAccessException) { throw (IllegalAccessException)t; } else if (t instanceof RuntimeException) { throw (RuntimeException)t; } else if (t instanceof Error) { throw (Error)t; } else { throw new Error("Unexpected invocation error", t); } } catch (IllegalAccessException iae) { // this can't happen throw new Error("Unexpected invocation error", iae); } } private static Method getTrampoline() { try { return AccessController.doPrivileged( new PrivilegedExceptionAction<Method>() { public Method run() throws Exception { Class<?> t = getTrampolineClass(); Class<?>[] types = { Method.class, Object.class, Object[].class }; Method b = t.getDeclaredMethod("invoke", types); b.setAccessible(true); return b; } }); } catch (Exception e) { throw new InternalError("bouncer cannot be found", e); } } protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { // First, check if the class has already been loaded ReflectUtil.checkPackageAccess(name); Class<?> c = findLoadedClass(name); if (c == null) { try { c = findClass(name); } catch (ClassNotFoundException e) { // Fall through ... } if (c == null) { c = getParent().loadClass(name); } } if (resolve) { resolveClass(c); } return c; } protected Class<?> findClass(final String name) throws ClassNotFoundException { if (!name.startsWith(MISC_PKG)) { throw new ClassNotFoundException(name); } String path = name.replace('.', '/').concat(".class"); URL res = getResource(path); if (res != null) { try { return defineClass(name, res); } catch (IOException e) { throw new ClassNotFoundException(name, e); } } else { throw new ClassNotFoundException(name); } } /* * Define the proxy classes */ private Class<?> defineClass(String name, URL url) throws IOException { byte[] b = getBytes(url); CodeSource cs = new CodeSource(null, (java.security.cert.Certificate[])null); if (!name.equals(TRAMPOLINE)) { throw new IOException("MethodUtil: bad name " + name); } return defineClass(name, b, 0, b.length, cs); } /* * Returns the contents of the specified URL as an array of bytes. */ private static byte[] getBytes(URL url) throws IOException { URLConnection uc = url.openConnection(); if (uc instanceof java.net.HttpURLConnection) { java.net.HttpURLConnection huc = (java.net.HttpURLConnection) uc; int code = huc.getResponseCode(); if (code >= java.net.HttpURLConnection.HTTP_BAD_REQUEST) { throw new IOException("open HTTP connection failed."); } } int len = uc.getContentLength(); try (InputStream in = new BufferedInputStream(uc.getInputStream())) { byte[] b = IOUtils.readAllBytes(in); if (len != -1 && b.length != len) throw new EOFException("Expected:" + len + ", read:" + b.length); return b; } } protected PermissionCollection getPermissions(CodeSource codesource) { PermissionCollection perms = super.getPermissions(codesource); perms.add(new AllPermission()); return perms; } private static Class<?> getTrampolineClass() { try { return Class.forName(TRAMPOLINE, true, new MethodUtil()); } catch (ClassNotFoundException e) { } return null; } }