objectoutputstream.java

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

    private void writeNonProxyDesc(ObjectStreamClass desc, boolean unshared) 
	throws IOException 
    {
	bout.writeByte(TC_CLASSDESC);
	handles.assign(unshared ? null : desc);
	
	if (protocol == PROTOCOL_VERSION_1) {
	    // do not invoke class descriptor write hook with old protocol
	    desc.writeNonProxy(this);
	} else {
	    writeClassDescriptor(desc);
	}
	
	Class cl = desc.forClass();
	bout.setBlockDataMode(true);
	annotateClass(cl);
	bout.setBlockDataMode(false);
	bout.writeByte(TC_ENDBLOCKDATA);
	
	writeClassDesc(desc.getSuperDesc(), false);
    }
    
    /**
     * Writes given string to stream, using standard or long UTF format
     * depending on string length.
     */
    private void writeString(String str, boolean unshared) throws IOException {
	handles.assign(unshared ? null : str);
	long utflen = bout.getUTFLength(str);
	if (utflen <= 0xFFFF) {
	    bout.writeByte(TC_STRING);
	    bout.writeUTF(str, utflen);
	} else {
	    bout.writeByte(TC_LONGSTRING);
	    bout.writeLongUTF(str, utflen);
	}
    }
    
    /**
     * Writes given array object to stream.
     */
    private void writeArray(Object array, 
			    ObjectStreamClass desc, 
			    boolean unshared) 
	throws IOException 
    {
	bout.writeByte(TC_ARRAY);
	writeClassDesc(desc, false);
	handles.assign(unshared ? null : array);
	
	Class ccl = desc.forClass().getComponentType();
	if (ccl.isPrimitive()) {
	    if (ccl == Integer.TYPE) {
		int[] ia = (int[]) array;
		bout.writeInt(ia.length);
		bout.writeInts(ia, 0, ia.length);
	    } else if (ccl == Byte.TYPE) {
		byte[] ba = (byte[]) array;
		bout.writeInt(ba.length);
		bout.write(ba, 0, ba.length, true);
	    } else if (ccl == Long.TYPE) {
		long[] ja = (long[]) array;
		bout.writeInt(ja.length);
		bout.writeLongs(ja, 0, ja.length);
	    } else if (ccl == Float.TYPE) {
		float[] fa = (float[]) array;
		bout.writeInt(fa.length);
		bout.writeFloats(fa, 0, fa.length);
	    } else if (ccl == Double.TYPE) {
		double[] da = (double[]) array;
		bout.writeInt(da.length);
		bout.writeDoubles(da, 0, da.length);
	    } else if (ccl == Short.TYPE) {
		short[] sa = (short[]) array;
		bout.writeInt(sa.length);
		bout.writeShorts(sa, 0, sa.length);
	    } else if (ccl == Character.TYPE) {
		char[] ca = (char[]) array;
		bout.writeInt(ca.length);
		bout.writeChars(ca, 0, ca.length);
	    } else if (ccl == Boolean.TYPE) {
		boolean[] za = (boolean[]) array;
		bout.writeInt(za.length);
		bout.writeBooleans(za, 0, za.length);
	    } else {
		throw new InternalError();
	    }
	} else {
	    Object[] objs = (Object[]) array;
	    int len = objs.length;
	    bout.writeInt(len);
	    for (int i = 0; i < len; i++) {
		writeObject0(objs[i], false);
	    }
	}
    }
    
    /**
     * Writes representation of a "ordinary" (i.e., not a String, Class,
     * ObjectStreamClass or array) serializable object to the stream.
     */
    private void writeOrdinaryObject(Object obj, 
				     ObjectStreamClass desc, 
				     boolean unshared) 
	throws IOException 
    {
	bout.writeByte(TC_OBJECT);
	writeClassDesc(desc, false);
	handles.assign(unshared ? null : obj);

	if (desc.isExternalizable() && !desc.isProxy()) {
	    writeExternalData((Externalizable) obj);
	} else {
	    writeSerialData(obj, desc);
	}
    }
    
    /**
     * Writes externalizable data of given object by invoking its
     * writeExternal() method.
     */
    private void writeExternalData(Externalizable obj) throws IOException {
	Object oldObj = curObj;
	ObjectStreamClass oldDesc = curDesc;
	PutFieldImpl oldPut = curPut;
	curObj = obj;
	curDesc = null;
	curPut = null;
	
	if (protocol == PROTOCOL_VERSION_1) {
	    obj.writeExternal(this);
	} else {
	    bout.setBlockDataMode(true);
	    obj.writeExternal(this);
	    bout.setBlockDataMode(false);
	    bout.writeByte(TC_ENDBLOCKDATA);
	}

	curObj = oldObj;
	curDesc = oldDesc;
	curPut = oldPut;
    }
    
    /**
     * Writes instance data for each serializable class of given object, from
     * superclass to subclass.
     */
    private void writeSerialData(Object obj, ObjectStreamClass desc) 
	throws IOException 
    {
	ObjectStreamClass.ClassDataSlot[] slots = desc.getClassDataLayout();
	for (int i = 0; i < slots.length; i++) {
	    ObjectStreamClass slotDesc = slots[i].desc;
	    if (slotDesc.hasWriteObjectMethod()) {
		Object oldObj = curObj;
		ObjectStreamClass oldDesc = curDesc;
		PutFieldImpl oldPut = curPut;
		curObj = obj;
		curDesc = slotDesc;
		curPut = null;

		bout.setBlockDataMode(true);
		slotDesc.invokeWriteObject(obj, this);
		bout.setBlockDataMode(false);
		bout.writeByte(TC_ENDBLOCKDATA);

		curObj = oldObj;
		curDesc = oldDesc;
		curPut = oldPut;
	    } else {
		defaultWriteFields(obj, slotDesc);
	    }
	}
    }
    
    /**
     * Fetches and writes values of serializable fields of given object to
     * stream.  The given class descriptor specifies which field values to
     * write, and in which order they should be written.
     */
    private void defaultWriteFields(Object obj, ObjectStreamClass desc)
	throws IOException
    {
	// TODO: perform conservative isInstance check here?
	desc.checkDefaultSerialize();

	int primDataSize = desc.getPrimDataSize();
	if (primVals == null || primVals.length < primDataSize) {
	    primVals = new byte[primDataSize];
	}
	desc.getPrimFieldValues(obj, primVals);
	bout.write(primVals, 0, primDataSize, false);
	
	ObjectStreamField[] fields = desc.getFields(false);
	Object[] objVals = new Object[desc.getNumObjFields()];
	int numPrimFields = fields.length - objVals.length;
	desc.getObjFieldValues(obj, objVals);
	for (int i = 0; i < objVals.length; i++) {
	    writeObject0(objVals[i], fields[numPrimFields + i].isUnshared());
	}
    }

    /**
     * Attempts to write to stream fatal IOException that has caused
     * serialization to abort.
     */
    private void writeFatalException(IOException ex) throws IOException {
	/*
	 * Note: the serialization specification states that if a second
	 * IOException occurs while attempting to serialize the original fatal
	 * exception to the stream, then a StreamCorruptedException should be
	 * thrown (section 2.1).  However, due to a bug in previous
	 * implementations of serialization, StreamCorruptedExceptions were
	 * rarely (if ever) actually thrown--the "root" exceptions from
	 * underlying streams were thrown instead.  This historical behavior is
	 * followed here for consistency.
	 */
	clear();
	boolean oldMode = bout.setBlockDataMode(false);
	try {
	    bout.writeByte(TC_EXCEPTION);
	    writeObject0(ex, false);
	    clear();
	} finally {
	    bout.setBlockDataMode(oldMode);
	}
    }

    /**
     * Converts specified span of float values into byte values.
     */
    // TODO: remove once hotspot inlines Float.floatToIntBits
    private static native void floatsToBytes(float[] src, int srcpos, 
					     byte[] dst, int dstpos, 
					     int nfloats);

    /**
     * Converts specified span of double values into byte values.
     */
    // TODO: remove once hotspot inlines Double.doubleToLongBits
    private static native void doublesToBytes(double[] src, int srcpos,
					      byte[] dst, int dstpos, 
					      int ndoubles);

    /**
     * Default PutField implementation.
     */
    private class PutFieldImpl extends PutField {

	/** class descriptor describing serializable fields */
	private final ObjectStreamClass desc;
	/** primitive field values */
	private final byte[] primVals;
	/** object field values */
	private final Object[] objVals;

	/**
	 * Creates PutFieldImpl object for writing fields defined in given
	 * class descriptor.
	 */
	PutFieldImpl(ObjectStreamClass desc) {
	    this.desc = desc;
	    primVals = new byte[desc.getPrimDataSize()];
	    objVals = new Object[desc.getNumObjFields()];
	}

	public void put(String name, boolean val) {
	    Bits.putBoolean(primVals, getFieldOffset(name, Boolean.TYPE), val);
	}

	public void put(String name, byte val) {
	    primVals[getFieldOffset(name, Byte.TYPE)] = val;
	}

	public void put(String name, char val) {
	    Bits.putChar(primVals, getFieldOffset(name, Character.TYPE), val);
	}

	public void put(String name, short val) {
	    Bits.putShort(primVals, getFieldOffset(name, Short.TYPE), val);
	}

	public void put(String name, int val) {
	    Bits.putInt(primVals, getFieldOffset(name, Integer.TYPE), val);
	}

	public void put(String name, float val) {
	    Bits.putFloat(primVals, getFieldOffset(name, Float.TYPE), val);
	}

	public void put(String name, long val) {
	    Bits.putLong(primVals, getFieldOffset(name, Long.TYPE), val);
	}

	public void put(String name, double val) {
	    Bits.putDouble(primVals, getFieldOffset(name, Double.TYPE), val);
	}

	public void put(String name, Object val) {
	    objVals[getFieldOffset(name, Object.class)] = val;
	}

	// deprecated in ObjectOutputStream.PutField
	public void write(ObjectOutput out) throws IOException {
	    /*
	     * Applications should *not* use this method to write PutField
	     * data, as it will lead to stream corruption if the PutField
	     * object writes any primitive data (since block data mode is not
	     * unset/set properly, as is done in OOS.writeFields()).  This
	     * broken implementation is being retained solely for behavioral
	     * compatibility, in order to support applications which use
	     * OOS.PutField.write() for writing only non-primitive data.
	     * 
	     * Serialization of unshared objects is not implemented here since
	     * it is not necessary for backwards compatibility; also, unshared
	     * semantics may not be supported by the given ObjectOutput
	     * instance.  Applications which write unshared objects using the
	     * PutField API must use OOS.writeFields().
	     */
	    out.write(primVals, 0, primVals.length);
	    
	    ObjectStreamField[] fields = desc.getFields(false);
	    int numPrimFields = fields.length - objVals.length;
	    // TODO: warn if numPrimFields > 0?
	    for (int i = 0; i < objVals.length; i++) {
		if (fields[numPrimFields + i].isUnshared()) {
		    throw new IOException("cannot write unshared object");
		}
		out.writeObject(objVals[i]);
	    }
	}
	
	/**
	 * Writes buffered primitive data and object fields to stream.
	 */
	void writeFields() throws IOException {
	    bout.write(primVals, 0, primVals.length, false);

	    ObjectStreamField[] fields = desc.getFields(false);
	    int numPrimFields = fields.length - objVals.length;
	    for (int i = 0; i < objVals.length; i++) {
		writeObject0(
		    objVals[i], fields[numPrimFields + i].isUnshared());
	    }
	}
	
	/**
	 * Returns offset of field with given name and type.  A specified type
	 * of null matches all types, Object.class matches all non-primitive
	 * types, and any other non-null type matches assignable types only.
	 * Throws IllegalArgumentException if no matching field found.
	 */
	private int getFieldOffset(String name, Class type) {
	    ObjectStreamField field = desc.getField(name, type);
	    if (field == null) {
		throw new IllegalArgumentException("no such field");
	    }
	    return field.getOffset();
	}
    }

    /**
     * Buffered output stream with two modes: in default mode, outputs data in
     * same format as DataOutputStream; in "block data" mode, outputs data
     * bracketed by block data markers (see object serialization specification
     * for details).
     */
    private static class BlockDataOutputStream 
	extends OutputStream implements DataOutput
    {
	/** maximum data block length */
	private static final int MAX_BLOCK_SIZE = 1024;
	/** maximum data block header length */
	private static final int MAX_HEADER_SIZE = 5;
	/** (tunable) length of char buffer (for writing strings) */
	private static final int CHAR_BUF_SIZE = 256;

	/** buffer for writing general/block data */
	private final byte[] buf = new byte[MAX_BLOCK_SIZE];
	/** buffer for writing block data headers */
	private final byte[] hbuf = new byte[MAX_HEADER_SIZE];
	/** char buffer for fast string writes */
	private final char[] cbuf = new char[CHAR_BUF_SIZE];
	
	/** block data mode */
	private boolean blkmode = false;
	/** current offset into buf */
	private int pos = 0;

	/** underlying output stream */
	private final OutputStream out;
	/** loopback stream (for data writes that span data blocks) */
	private final DataOutputStream dout;

	/**
	 * Creates new BlockDataOutputStream on top of given underlying stream.