import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; import java.util.Properties; public class Serialize implements Serializable { public static final long serialVersionUID = 1l; public int dummy = 0x12345678; private static void expect(boolean v) { if (! v) throw new RuntimeException(); } private static void expectEqual(boolean a, boolean b) { expect(a == b); } private static void expectEqual(int a, int b) { expect(a == b); } private static void expectEqual(String a, String b) { expect(a.equals(b)); } private static String pad(long number, int length) { return pad(Long.toHexString(number), length, '0'); } private static String pad(String s, int length, char padChar) { length -= s.length(); if (length <= 0) { return s; } StringBuilder builder = new StringBuilder(); while (length-- > 0) { builder.append(padChar); } return builder.append(s).toString(); } protected static void hexdump(byte[] a) { StringBuilder builder = new StringBuilder(); System.err.print(pad(0, 8) + " "); for (int i = 0; i < a.length; i++) { String hex = Integer.toHexString(a[i] & 0xff); System.err.print(" " + (hex.length() == 1 ? "0" : "") + hex); builder.append(a[i] < 0x20 || a[i] > 0x7f ? '.' : (char)a[i]); if ((i & 0xf) == 0x7) { System.err.print(" "); } else if ((i & 0xf) == 0xf) { System.err.println(" |" + builder + "|"); builder.setLength(0); System.err.print(pad(i + 1, 8) + " "); } } for (int i = a.length & 0xf; i < 0x10; i++) { System.err.print(" "); if ((i & 0xf) == 0x7) { System.err.print(" "); } } System.err.println(" |" + builder + "|"); } private static void expectEqual(byte[] a, int[] b) { expect(a.length == b.length); for (int i = 0; i < a.length; ++i) { expect(a[i] == (byte)b[i]); } } private static class MyMap implements Serializable { private transient Properties properties = new Properties(); public final static long serialVersionUID = 0x0cc1f63e2d256ae6l; public int size() { return properties.size(); } public void put(String key, String value) { properties.put(key, value); } public String get(String key) { return properties.getProperty(key); } private void writeObject(ObjectOutputStream out) throws IOException { out.defaultWriteObject(); out.writeInt(size()); for (Object key : properties.keySet()) { out.writeObject(key); out.writeObject(properties.get(key)); } } private void readObject(ObjectInputStream in) throws IOException { try { in.defaultReadObject(); } catch (Exception e) { // OpenJDK's defaultReadObject() can throw a ClassNotFoundException throw new IOException(e); } properties = new Properties(); int size = in.readInt(); for (int i = 0; i < size; i++) try { properties.put(in.readObject(), in.readObject()); } catch (ClassNotFoundException e) { throw new IOException(e); } } } public static void main(String[] args) throws Exception { ByteArrayOutputStream out = new ByteArrayOutputStream(); ObjectOutputStream out2 = new ObjectOutputStream(out); out2.writeBoolean(true); out2.flush(); out2.writeByte(17); out2.flush(); out2.writeInt(0xcafebabe); out2.flush(); out2.writeUTF("Max & Möritz"); out2.flush(); out2.writeChar('ɛ'); out2.flush(); out2.writeObject(new Serialize()); out2.close(); byte[] array = out.toByteArray(); expectEqual(array, new int[] { // magic 0xac, 0xed, // version 0x00, 0x05, // blockdata, length 0x77, 0x1, // true 1, // blockdata, length 0x77, 0x1, // (byte)17 17, // blockdata, length 0x77, 0x4, // 0xcafebabe 0xca, 0xfe, 0xba, 0xbe, // blockdata, length 0x77, 0xf, // "Max & Möritz" 0x0, 0xd, 'M', 'a', 'x', ' ', '&', ' ', 'M', 0xc3, 0xb6, 'r', 'i', 't', 'z', // blockdata, length 0x77, 0x2, // 'ö' 0x02, 0x5b, // object 0x73, // class desc, "Serialize" 0x72, 0, 9, 'S', 'e', 'r', 'i', 'a', 'l', 'i', 'z', 'e', // serialVersionUID 0, 0, 0, 0, 0, 0, 0, 1, // flags (SC_SERIALIZABLE) 2, // field count 0x0, 0x1, // int dummy 'I', 0x0, 0x5, 'd', 'u', 'm', 'm', 'y', // class annotation 0x78, // super class desc 0x70, // classdata[] 0x12, 0x34, 0x56, 0x78 }); ByteArrayInputStream in = new ByteArrayInputStream(array); ObjectInputStream in2 = new ObjectInputStream(in); expectEqual(true, in2.readBoolean()); expectEqual(17, in2.readByte()); expectEqual(0xcafebabe, in2.readInt()); expectEqual("Max & Möritz", in2.readUTF()); expectEqual('ɛ', in2.readChar()); Serialize unserialized = (Serialize) in2.readObject(); expectEqual(0x12345678, unserialized.dummy); in2.close(); out.reset(); out2 = new ObjectOutputStream(out); MyMap map = new MyMap(); map.put("key", "value"); out2.writeObject(map); out2.close(); array = out.toByteArray(); expectEqual(array, new int[] { // magic 0xac, 0xed, // version 0x00, 0x05, // object 0x73, // class desc "Serialize$MyMap" 0x72, 0, 15, 'S', 'e', 'r', 'i', 'a', 'l', 'i', 'z', 'e', '$', 'M', 'y', 'M', 'a', 'p', // serial version UID: 0x0cc1f64e2d266ae6 0x0c, 0xc1, 0xf6, 0x3e, 0x2d, 0x25, 0x6a, 0xe6, // flags: SC_SERIALIZABLE | SC_WRITE_METHOD 0x03, // no (non-transient) fields 0, 0, // class annotation 0x78, // super class desc 0x70, // custom TreeMap data written by TreeMap#writeObject 0x77, 4, 0x00 , 0x00, 0x00, 0x01, // (int)1 (== map.size()) 0x74, 0, 3, 'k', 'e', 'y', // "key" 0x74, 0, 5, 'v', 'a', 'l', 'u', 'e', // "value" // end block data 0x78 }); in = new ByteArrayInputStream(array); in2 = new ObjectInputStream(in); map = (MyMap)in2.readObject(); in2.close(); expectEqual(1, map.size()); expectEqual("value", (String)map.get("key")); } }