objectoutputstream.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 1,976 行 · 第 1/5 页

	bout.writeBytes(str);
    }

    /**
     * Writes a String as a sequence of chars.
     *
     * @param	str the String of chars to be written
     * @throws	IOException if I/O errors occur while writing to the underlying
     * 		stream
     */
    public void writeChars(String str) throws IOException {
	bout.writeChars(str);
    }

    /**
     * Primitive data write of this String in UTF format.
     *
     * Note that there is a significant difference between
     * writing a String into the stream as primitive data or
     * as an Object. A String instance written by writeObject
     * is written into the stream as a String initially. Future
     * writeObject() calls write references to the string into
     * the stream.
     *
     * @param str the String in UTF format
     * @throws IOException if I/O errors occur while writing to the underlying
     * stream
     */
    public void writeUTF(String str) throws IOException {
	bout.writeUTF(str);
    }
    
    /*
     * Gets the values of the primitive fields of object obj.  fieldIDs is an
     * array of field IDs (the primFieldsID field of the appropriate
     * ObjectStreamClass) identifying which fields to get.  typecodes is an
     * array of characters designating the primitive type of each field (e.g.,
     * 'C' for char, 'Z' for boolean, etc.)  data is the byte buffer in which
     * the primitive field values are written, in the order of their field IDs.
     * 
     * For efficiency, this method does not check all of its arguments for
     * safety.  Specifically, it assumes that obj's type is compatible with the
     * given field IDs, and that the data array is long enough to contain all of
     * the byte values that will be written to it.
     */
    static native void getPrimitiveFieldValues(Object obj, 
	    long[] fieldIDs, char[] typecodes, byte[] data);
    
    /*
     * Gets the value of an object field of object obj.  fieldID is the field ID
     * identifying which field to set (obtained from the objFieldsID array field
     * of the appropriate ObjectStreamClass).
     * 
     * For efficiency, this method does not check to make sure that obj's type
     * is compatible with the given field ID.
     */
    static native Object getObjectFieldValue(Object obj, long fieldID);

    /*************************************/

    /**
     * Provide programatic access to the persistent fields to be written
     * to ObjectOutput.
     *
     * @since 1.2
     */
    public static abstract class PutField {

	/**
	 * Put the value of the named boolean field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, boolean val);

	/**
	 * Put the value of the named byte field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, byte val);

	/**
	 * Put the value of the named char field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, char val);

	/**
	 * Put the value of the named short field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, short val);

	/**
	 * Put the value of the named int field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, int val);

	/**
	 * Put the value of the named long field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, long val);

	/**
	 * Put the value of the named float field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, float val);

	/**
	 * Put the value of the named double field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, double val);

	/**
	 * Put the value of the named Object field into the persistent field.
	 *
	 * @param  name the name of the serializable field
	 * @param  val the value to assign to the field
	 */
	public abstract void put(String name, Object val);

	/**
	 * Write the data and fields to the specified ObjectOutput stream.
	 * 
	 * @param out the stream to write the data and fields to
	 * @throws IOException if I/O errors occur while writing to the
	 * underlying stream
	 */
	public abstract void write(ObjectOutput out) throws IOException;
    }


    /**
     * Returns protocol version in use.
     */
    int getProtocolVersion() {
	return protocol;
    }

    /**
     * Writes string without allowing it to be replaced in stream.  Used by
     * ObjectStreamClass to write class descriptor type strings.
     */
    void writeTypeString(String str) throws IOException {
	int handle;
	if (str == null) {
	    writeNull();
	} else if ((handle = handles.lookup(str)) != -1) {
	    writeHandle(handle);
	} else {
	    writeString(str, false);
	}
    }

    /**
     * Verifies that this (possibly subclass) instance can be constructed
     * without violating security constraints: the subclass must not override
     * security-sensitive non-final methods, or else the
     * "enableSubclassImplementation" SerializablePermission is checked.
     */
    private void verifySubclass() {
        Class cl = getClass();
        synchronized (subclassAudits) {
            Boolean result = (Boolean) subclassAudits.get(cl);
            if (result == null) {
                 // 
                 // Note: only new Boolean instances (i.e., not Boolean.TRUE or
                 // Boolean.FALSE) must be used as cache values, otherwise cache
                 // entry will pin associated class.
                 //
                result = new Boolean(auditSubclass(cl));
                subclassAudits.put(cl, result);
            }
            if (result.booleanValue()) {
                return;
            }
        }
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(ObjectStreamConstants.SUBCLASS_IMPLEMENTATION_PERMISSION);
        }
    }

    /**
     * Performs reflective checks on given subclass to verify that it doesn't
     * override security-sensitive non-final methods.  Returns true if subclass
     * is "safe", false otherwise.
     */
    private static boolean auditSubclass(final Class subcl) {
        Boolean result = (Boolean) AccessController.doPrivileged(
            new PrivilegedAction() {
                public Object run() {
                    for (Class cl = subcl;
                         cl != ObjectOutputStream.class;
                         cl = cl.getSuperclass())
                    {
                        try {
                            cl.getDeclaredMethod(
                                "writeUnshared", new Class[] { Object.class });
                            return Boolean.FALSE;
                        } catch (NoSuchMethodException ex) {
                        }
                        try {
                            cl.getDeclaredMethod("putFields", new Class[0]);
                            return Boolean.FALSE;
                        } catch (NoSuchMethodException ex) {
                        }
                    }
                    return Boolean.TRUE;
                }
            }
        );
        return result.booleanValue();
    }

    /**
     * Clears internal data structures.
     */
    private void clear() {
	subs.clear();
	handles.clear();
    }

    /**
     * Underlying writeObject/writeUnshared implementation.
     */
    private void writeObject0(Object obj, boolean unshared) 
	throws IOException 
    {
	boolean oldMode = bout.setBlockDataMode(false);
	depth++;
	try {
	    // handle previously written and non-replaceable objects
	    int h;
	    if ((obj = subs.lookup(obj)) == null) {
		writeNull();
		return;
	    } else if (!unshared && (h = handles.lookup(obj)) != -1) {
		writeHandle(h);
		return;
	    } else if (obj instanceof Class) {
		writeClass((Class) obj, unshared);
		return;
	    } else if (obj instanceof ObjectStreamClass) {
		writeClassDesc((ObjectStreamClass) obj, unshared);
		return;
	    }
	    
	    // check for replacement object
	    Object orig = obj;
	    Class cl = obj.getClass();
	    ObjectStreamClass desc;
	    for (;;) {
		// TODO: skip this check for strings/arrays?
		Class repCl;
		desc = ObjectStreamClass.lookup(cl, true);
		if (!desc.hasWriteReplaceMethod() ||
		    (obj = desc.invokeWriteReplace(obj)) == null ||
		    (repCl = obj.getClass()) == cl)
		{
		    break;
		}
		cl = repCl;
	    }
	    if (enableReplace) {
		Object rep = replaceObject(obj);
		if (rep != obj && rep != null) {
		    cl = rep.getClass();
		    desc = ObjectStreamClass.lookup(cl, true);
		}
		obj = rep;
	    }

	    // if object replaced, run through original checks a second time
	    if (obj != orig) {
		subs.assign(orig, obj);
		if (obj == null) {
		    writeNull();
		    return;
		} else if (!unshared && (h = handles.lookup(obj)) != -1) {
		    writeHandle(h);
		    return;
		} else if (obj instanceof Class) {
		    writeClass((Class) obj, unshared);
		    return;
		} else if (obj instanceof ObjectStreamClass) {
		    writeClassDesc((ObjectStreamClass) obj, unshared);
		    return;
		}
	    }
	    
	    // remaining cases
	    if (obj instanceof String) {
		writeString((String) obj, unshared);
	    } else if (cl.isArray()) {
		writeArray(obj, desc, unshared);
	    } else if (obj instanceof Serializable) {
		writeOrdinaryObject(obj, desc, unshared);
	    } else {
		throw new NotSerializableException(cl.getName());
	    }
	} finally {
	    depth--;
	    bout.setBlockDataMode(oldMode);
	}
    }
    
    /**
     * Writes null code to stream.
     */
    private void writeNull() throws IOException {
	bout.writeByte(TC_NULL);
    }
    
    /**
     * Writes given object handle to stream.
     */
    private void writeHandle(int handle) throws IOException {
	bout.writeByte(TC_REFERENCE);
	bout.writeInt(baseWireHandle + handle);
    }
    
    /**
     * Writes representation of given class to stream.
     */
    private void writeClass(Class cl, boolean unshared) throws IOException {
	bout.writeByte(TC_CLASS);
	writeClassDesc(ObjectStreamClass.lookup(cl, true), false);
	handles.assign(unshared ? null : cl);
    }
    
    /**
     * Writes representation of given class descriptor to stream.
     */
    private void writeClassDesc(ObjectStreamClass desc, boolean unshared) 
	throws IOException 
    {
	int handle;
	if (desc == null) {
	    writeNull();
	} else if (!unshared && (handle = handles.lookup(desc)) != -1) {
	    writeHandle(handle);
	} else if (desc.isProxy()) {
	    writeProxyDesc(desc, unshared);
	} else {
	    writeNonProxyDesc(desc, unshared);
	}
    }
    
    /**
     * Writes class descriptor representing a dynamic proxy class to stream.
     */
    private void writeProxyDesc(ObjectStreamClass desc, boolean unshared) 
	throws IOException 
    {
	bout.writeByte(TC_PROXYCLASSDESC);
	handles.assign(unshared ? null : desc);

	Class cl = desc.forClass();
	Class[] ifaces = cl.getInterfaces();
	bout.writeInt(ifaces.length);
	for (int i = 0; i < ifaces.length; i++) {
	    bout.writeUTF(ifaces[i].getName());
	}
	
	bout.setBlockDataMode(true);
	annotateProxyClass(cl);
	bout.setBlockDataMode(false);
	bout.writeByte(TC_ENDBLOCKDATA);
	
	writeClassDesc(desc.getSuperDesc(), false);
    }
    
    /**
     * Writes class descriptor representing a standard (i.e., not a dynamic
     * proxy) class to stream.
     */