/**
* Copyright 2006-2009 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.objenesis.instantiator.basic;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.NotSerializableException;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.io.ObjectStreamConstants;
import java.io.Serializable;
import org.objenesis.ObjenesisException;
import org.objenesis.instantiator.ObjectInstantiator;
/**
* Instantiates a class by using a dummy input stream that always feeds data for an empty object of
* the same kind. NOTE: This instantiator may not work properly if the class being instantiated
* defines a "readResolve" method, since it may return objects that have been returned previously
* (i.e., there's no guarantee that the returned object is a new one), or even objects from a
* completely different class.
*
* @author Leonardo Mesquita
* @see org.objenesis.instantiator.ObjectInstantiator
*/
public class ObjectInputStreamInstantiator implements ObjectInstantiator {
private static class MockStream extends InputStream {
private int pointer;
private byte[] data;
private int sequence;
private static final int[] NEXT = new int[] {1, 2, 2};
private byte[][] buffers;
private final byte[] FIRST_DATA;
private static byte[] HEADER;
private static byte[] REPEATING_DATA;
static {
initialize();
}
private static void initialize() {
try {
ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
DataOutputStream dout = new DataOutputStream(byteOut);
dout.writeShort(ObjectStreamConstants.STREAM_MAGIC);
dout.writeShort(ObjectStreamConstants.STREAM_VERSION);
HEADER = byteOut.toByteArray();
byteOut = new ByteArrayOutputStream();
dout = new DataOutputStream(byteOut);
dout.writeByte(ObjectStreamConstants.TC_OBJECT);
dout.writeByte(ObjectStreamConstants.TC_REFERENCE);
dout.writeInt(ObjectStreamConstants.baseWireHandle);
REPEATING_DATA = byteOut.toByteArray();
}
catch(IOException e) {
throw new Error("IOException: " + e.getMessage());
}
}
public MockStream(Class clazz) {
this.pointer = 0;
this.sequence = 0;
this.data = HEADER;
// (byte) TC_OBJECT
// (byte) TC_CLASSDESC
// (short length)
// (byte * className.length)
// (long)serialVersionUID
// (byte) SC_SERIALIZABLE
// (short)0 <fields>
// TC_ENDBLOCKDATA
// TC_NULL
ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
DataOutputStream dout = new DataOutputStream(byteOut);
try {
dout.writeByte(ObjectStreamConstants.TC_OBJECT);
dout.writeByte(ObjectStreamConstants.TC_CLASSDESC);
dout.writeUTF(clazz.getName());
dout.writeLong(ObjectStreamClass.lookup(clazz).getSerialVersionUID());
dout.writeByte(ObjectStreamConstants.SC_SERIALIZABLE);
dout.writeShort((short) 0); // Zero fields
dout.writeByte(ObjectStreamConstants.TC_ENDBLOCKDATA);
dout.writeByte(ObjectStreamConstants.TC_NULL);
}
catch(IOException e) {
throw new Error("IOException: " + e.getMessage());
}
this.FIRST_DATA = byteOut.toByteArray();
buffers = new byte[][] {HEADER, FIRST_DATA, REPEATING_DATA};
}
private void advanceBuffer() {
pointer = 0;
sequence = NEXT[sequence];
data = buffers[sequence];
}
public int read() throws IOException {
int result = data[pointer++];
if(pointer >= data.length) {
advanceBuffer();
}
return result;
}
public int available() throws IOException {
return Integer.MAX_VALUE;
}
public int read(byte[] b, int off, int len) throws IOException {
int left = len;
int remaining = data.length - pointer;
while(remaining <= left) {
System.arraycopy(data, pointer, b, off, remaining);
off += remaining;
left -= remaining;
advanceBuffer();
remaining = data.length - pointer;
}
if(left > 0) {
System.arraycopy(data, pointer, b, off, left);
pointer += left;
}
return len;
}
}
private ObjectInputStream inputStream;
public ObjectInputStreamInstantiator(Class clazz) {
if(Serializable.class.isAssignableFrom(clazz)) {
try {
this.inputStream = new ObjectInputStream(new MockStream(clazz));
}
catch(IOException e) {
throw new Error("IOException: " + e.getMessage());
}
}
else {
throw new ObjenesisException(new NotSerializableException(clazz+" not serializable"));
}
}
public Object newInstance() {
try {
return inputStream.readObject();
}
catch(ClassNotFoundException e) {
throw new Error("ClassNotFoundException: " + e.getMessage());
}
catch(Exception e) {
throw new ObjenesisException(e);
}
}
}