objectstreamclass.java

java jdk 1.4的源码

     *
     * Only compare base class name to allow package renaming.
     */
    static boolean compareClassNames(String streamName,
				     String localName,
				     char pkgSeparator) {
	/* compare the class names, stripping off package names. */
	int streamNameIndex = streamName.lastIndexOf(pkgSeparator);
	if (streamNameIndex < 0)
	    streamNameIndex = 0;

	int localNameIndex = localName.lastIndexOf(pkgSeparator);
	if (localNameIndex < 0)
	    localNameIndex = 0;

	return streamName.regionMatches(false, streamNameIndex,
					localName, localNameIndex,
					streamName.length() - streamNameIndex);
    }

    /*
     * Compare the types of two class descriptors.
     * They match if they have the same class name and suid
     */
    final boolean typeEquals(ObjectStreamClass other) {
	return (suid == other.suid) &&
	    compareClassNames(name, other.name, '.');
    }

    /*
     * Return the superclass descriptor of this descriptor.
     */
    final void setSuperclass(ObjectStreamClass s) {
	superclass = s;
    }

    /*
     * Return the superclass descriptor of this descriptor.
     */
    final ObjectStreamClass getSuperclass() {
	return superclass;
    }

    /*
     * Return whether the class has a writeObject method
     */
    final boolean hasWriteObject() {
	return hasWriteObjectMethod;
    }

    final boolean isCustomMarshaled() {
	return (hasWriteObject() || isExternalizable());
    }

    /*
     * Return true if all instances of 'this' Externalizable class
     * are written in block-data mode from the stream that 'this' was read
     * from. <p>
     *
     * In JDK 1.1, all Externalizable instances are not written
     * in block-data mode.
     * In JDK 1.2, all Externalizable instances, by default, are written
     * in block-data mode and the Externalizable instance is terminated with
     * tag TC_ENDBLOCKDATA. Change enabled the ability to skip Externalizable
     * instances.
     *
     * IMPLEMENTATION NOTE:
     *   This should have been a mode maintained per stream; however,
     *   for compatibility reasons, it was only possible to record
     *   this change per class. All Externalizable classes within
     *   a given stream should either have this mode enabled or
     *   disabled. This is enforced by not allowing the PROTOCOL_VERSION
     *   of a stream to he changed after any objects have been written.
     *
     * @see ObjectOuputStream#useProtocolVersion
     * @see ObjectStreamConstants#PROTOCOL_VERSION_1
     * @see ObjectStreamConstants#PROTOCOL_VERSION_2
     *
     * @since JDK 1.2
     */
    boolean hasExternalizableBlockDataMode() {
	return hasExternalizableBlockData;
    }

    /*
     * Return the ObjectStreamClass of the local class this one is based on.
     */
    final ObjectStreamClass localClassDescriptor() {
	return localClassDesc;
    }

    /*
     * Get the Serializability of the class.
     */
    boolean isSerializable() {
	return serializable;
    }

    /*
     * Get the externalizability of the class.
     */
    boolean isExternalizable() {
	return externalizable;
    }

    boolean isNonSerializable() {
        return ! (externalizable || serializable);
    }

    /*
     * Calculate the size of the array needed to store primitive data and the
     * number of object references to read when reading from the input
     * stream.
     */
    private void computeFieldInfo() {
	primBytes = 0;
	objFields = 0;

	for (int i = 0; i < fields.length; i++ ) {
	    switch (fields[i].getTypeCode()) {
	    case 'B':
	    case 'Z':
	    	primBytes += 1;
	    	break;
	    case 'C':
	    case 'S':
	    	primBytes += 2;
	    	break;

	    case 'I':
	    case 'F':
	    	primBytes += 4;
	    	break;
	    case 'J':
	    case 'D' :
	    	primBytes += 8;
	    	break;

	    case 'L':
	    case '[':
	    	objFields += 1;
	    	break;
	    }
	}
    }

    /*
     * Compute a hash for the specified class.  Incrementally add
     * items to the hash accumulating in the digest stream.
     * Fold the hash into a long.  Use the SHA secure hash function.
     */
    private static long _computeSerialVersionUID(Class cl) {
	ByteArrayOutputStream devnull = new ByteArrayOutputStream(512);

	long h = 0;
	try {
	    MessageDigest md = MessageDigest.getInstance("SHA");
	    DigestOutputStream mdo = new DigestOutputStream(devnull, md);
	    DataOutputStream data = new DataOutputStream(mdo);


	    data.writeUTF(cl.getName());

	    int classaccess = cl.getModifiers();
	    classaccess &= (Modifier.PUBLIC | Modifier.FINAL |
			    Modifier.INTERFACE | Modifier.ABSTRACT);

	    /* Workaround for javac bug that only set ABSTRACT for
	     * interfaces if the interface had some methods.
	     * The ABSTRACT bit reflects that the number of methods > 0.
	     * This is required so correct hashes can be computed
	     * for existing class files.
	     * Previously this hack was previously present in the VM.
	     */
            Method[] method = cl.getDeclaredMethods();
	    if ((classaccess & Modifier.INTERFACE) != 0) {
		classaccess &= (~Modifier.ABSTRACT);
		if (method.length > 0) {
		    classaccess |= Modifier.ABSTRACT;
		}
	    }

	    data.writeInt(classaccess);

	    /*
	     * Get the list of interfaces supported,
	     * Accumulate their names their names in Lexical order
	     * and add them to the hash
	     */
            if (!cl.isArray()) {
                /* In 1.2fcs, getInterfaces() was modified to return
                 * {java.lang.Cloneable, java.io.Serializable} when
                 * called on array classes.  These values would upset
                 * the computation of the hash, so we explicitly omit
                 * them from its computation.
                 */

	        Class interfaces[] = cl.getInterfaces();
	        Arrays.sort(interfaces, compareClassByName);

	        for (int i = 0; i < interfaces.length; i++) {
		    data.writeUTF(interfaces[i].getName());
	        }
	    }

	    /* Sort the field names to get a deterministic order */
            Field[] field = cl.getDeclaredFields();
	    Arrays.sort(field, compareMemberByName);

	    for (int i = 0; i < field.length; i++) {
		Field f = field[i];

		/* Include in the hash all fields except those that are
		 * private transient and private static.
		 */
		int m = f.getModifiers();
		if (Modifier.isPrivate(m) &&
		    (Modifier.isTransient(m) || Modifier.isStatic(m)))
		    continue;

		data.writeUTF(f.getName());
		data.writeInt(m);
		data.writeUTF(getSignature(f.getType()));
	    }

	    if (hasStaticInitializer(cl)) {
		data.writeUTF("<clinit>");
		data.writeInt(Modifier.STATIC); // TBD: what modifiers does it have
		data.writeUTF("()V");
	    }

	    /*
	     * Get the list of constructors including name and signature
	     * Sort lexically, add all except the private constructors
	     * to the hash with their access flags
	     */

	    MethodSignature[] constructors =
		MethodSignature.removePrivateAndSort(cl.getDeclaredConstructors());
	    for (int i = 0; i < constructors.length; i++) {
		MethodSignature c = constructors[i];
		String mname = "<init>";
		String desc = c.signature;
		desc = desc.replace('/', '.');
		data.writeUTF(mname);
		data.writeInt(c.member.getModifiers());
		data.writeUTF(desc);
	    }

	    /* Include in the hash all methods except those that are
	     * private transient and private static.
	     */
	    MethodSignature[] methods =
		MethodSignature.removePrivateAndSort(method);
	    for (int i = 0; i < methods.length; i++ ) {
		MethodSignature m = methods[i];
		String desc = m.signature;
		desc = desc.replace('/', '.');
		data.writeUTF(m.member.getName());
		data.writeInt(m.member.getModifiers());
		data.writeUTF(desc);
	    }

	    /* Compute the hash value for this class.
	     * Use only the first 64 bits of the hash.
	     */
	    data.flush();
	    byte hasharray[] = md.digest();
	    for (int i = 0; i < Math.min(8, hasharray.length); i++) {
		h += (long)(hasharray[i] & 255) << (i * 8);
	    }
	} catch (IOException ignore) {
	    /* can't happen, but be deterministic anyway. */
	    h = -1;
	} catch (NoSuchAlgorithmException complain) {
	    throw new SecurityException(complain.getMessage());
	}
	return h;
    }

    private static long computeStructuralUID(com.sun.corba.se.internal.io.ObjectStreamClass osc, Class cl) {
	ByteArrayOutputStream devnull = new ByteArrayOutputStream(512);
		
	long h = 0;
	try {

	    if ((!java.io.Serializable.class.isAssignableFrom(cl)) ||
		(cl.isInterface())){
		return 0;
	    }
			
	    if (java.io.Externalizable.class.isAssignableFrom(cl)) {
		return 1;
	    }

	    MessageDigest md = MessageDigest.getInstance("SHA");
	    DigestOutputStream mdo = new DigestOutputStream(devnull, md);
	    DataOutputStream data = new DataOutputStream(mdo);

	    // Get SUID of parent
	    Class parent = cl.getSuperclass();
	    if ((parent != null))  
	    // SerialBug 1; acc. to spec the one for 
	    // java.lang.object
	    // should be computed and put
	    //     && (parent != java.lang.Object.class)) 
	    {
				//data.writeLong(computeSerialVersionUID(null,parent));
		data.writeLong(computeStructuralUID(lookup(parent), parent));
	    }

	    if (osc.hasWriteObject())
		data.writeInt(2);
	    else
		data.writeInt(1);

            // CORBA formal 00-11-03 10.6.2:  For each field of the
            // class that is mapped to IDL, sorted lexicographically
            // by Java field name, in increasing order...
            ObjectStreamField[] field = osc.getFields();
            if (field.length > 1) {
                Arrays.sort(field, compareObjStrFieldsByName);
            }

            // ...Java field name in UTF encoding, field
            // descriptor, as defined by the JVM spec...
            for (int i = 0; i < field.length; i++) {
                data.writeUTF(field[i].getName());
                data.writeUTF(field[i].getSignature());
            }
			
	    /* Compute the hash value for this class.
	     * Use only the first 64 bits of the hash.
	     */
	    data.flush();
	    byte hasharray[] = md.digest();
	    // int minimum = Math.min(8, hasharray.length);
	    // SerialBug 3: SHA computation is wrong; for loop reversed
	    //for (int i = minimum; i > 0; i--) 
	    for (int i = 0; i < Math.min(8, hasharray.length); i++) {
		h += (long)(hasharray[i] & 255) << (i * 8);
	    }
	} catch (IOException ignore) {
	    /* can't happen, but be deterministic anyway. */
	    h = -1;
	} catch (NoSuchAlgorithmException complain) {
	    throw new SecurityException(complain.getMessage());
	}
	return h;
    }

    /**
     * Compute the JVM signature for the class.
     */
    static String getSignature(Class clazz) {
	String type = null;
	if (clazz.isArray()) {
	    Class cl = clazz;
	    int dimensions = 0;
	    while (cl.isArray()) {
		dimensions++;
		cl = cl.getComponentType();
	    }
	    StringBuffer sb = new StringBuffer();
	    for (int i = 0; i < dimensions; i++) {
		sb.append("[");
	    }
	    sb.append(getSignature(cl));
	    type = sb.toString();
	} else if (clazz.isPrimitive()) {
	    if (clazz == Integer.TYPE) {
		type = "I";
	    } else if (clazz == Byte.TYPE) {
		type = "B";
	    } else if (clazz == Long.TYPE) {
		type = "J";
	    } else if (clazz == Float.TYPE) {
		type = "F";
	    } else if (clazz == Double.TYPE) {
		type = "D";
	    } else if (clazz == Short.TYPE) {
		type = "S";
	    } else if (clazz == Character.TYPE) {
		type = "C";
	    } else if (clazz == Boolean.TYPE) {
		type = "Z";
	    } else if (clazz == Void.TYPE) {
		type = "V";
	    }
	} else {
	    type = "L" + clazz.getName().replace('.', '/') + ";";
	}
	return type;
    }

    /*
     * Compute the JVM method descriptor for the method.
     */