Obtener Valor Serializado de un Objeto en un String

Hasta hace poco pensaba que existía una manera directa de obtener el valor serializado de un objeto como una cadena de caracteres (String). Necesitaba el valor String para guardarlo en una base de datos. Resulta que todos los ejemplos que encontraba grababan el valor serializado en bytes en un archivo.

Finalmente encontré una solución en un foro que quiero replicar en este blog. La solución require utilizar esta clase que tiene licencia GPL:Base64

package com.eol.common.util;
package com.eol.common.util;

//Copyright 2003-2010 Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland
//www.source-code.biz, www.inventec.ch/chdh
//
//This module is multi-licensed and may be used under the terms
//of any of the following licenses:
//
//EPL, Eclipse Public License, V1.0 or later, http://www.eclipse.org/legal
//LGPL, GNU Lesser General Public License, V2.1 or later, http://www.gnu.org/licenses/lgpl.html
//GPL, GNU General Public License, V2 or later, http://www.gnu.org/licenses/gpl.html
//AL, Apache License, V2.0 or later, http://www.apache.org/licenses
//BSD, BSD License, http://www.opensource.org/licenses/bsd-license.php
//
//Please contact the author if you need another license.
//This module is provided "as is", without warranties of any kind.


/**
* A Base64 encoder/decoder.
*
* <p>
* This class is used to encode and decode data in Base64 format as described in RFC 1521.
*
* <p>
* Project home page: <a href="http://www.source-code.biz/base64coder/java/">www.source-code.biz/base64coder/java</a><br>
* Author: Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland<br>
* Multi-licensed: EPL / LGPL / GPL / AL / BSD.
*/
public class Base64Coder {

 //The line separator string of the operating system.
 private static final String systemLineSeparator = System.getProperty("line.separator");
 
 //Mapping table from 6-bit nibbles to Base64 characters.
 private static char[]    map1 = new char[64];
 static {
    int i=0;
    for (char c='A'; c<='Z'; c++) map1[i++] = c;
    for (char c='a'; c<='z'; c++) map1[i++] = c;
    for (char c='0'; c<='9'; c++) map1[i++] = c;
    map1[i++] = '+'; map1[i++] = '/'; }
 
 //Mapping table from Base64 characters to 6-bit nibbles.
 private static byte[]    map2 = new byte[128];
 static {
    for (int i=0; i<map2.length; i++) map2[i] = -1;
    for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; }
 
 /**
 * Encodes a string into Base64 format.
 * No blanks or line breaks are inserted.
 * @param s  A String to be encoded.
 * @return   A String containing the Base64 encoded data.
 */
 public static String encodeString (String s) {
 return new String(encode(s.getBytes())); }
 
 /**
 * Encodes a byte array into Base 64 format and breaks the output into lines of 76 characters.
 * This method is compatible with <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>.
 * @param in  An array containing the data bytes to be encoded.
 * @return    A String containing the Base64 encoded data, broken into lines.
 */
 public static String encodeLines (byte[] in) {
 return encodeLines(in, 0, in.length, 76, systemLineSeparator); }
 
 /**
 * Encodes a byte array into Base 64 format and breaks the output into lines.
 * @param in            An array containing the data bytes to be encoded.
 * @param iOff          Offset of the first byte in <code>in</code> to be processed.
 * @param iLen          Number of bytes to be processed in <code>in</code>, starting at <code>iOff</code>.
 * @param lineLen       Line length for the output data. Should be a multiple of 4.
 * @param lineSeparator The line separator to be used to separate the output lines.
 * @return              A String containing the Base64 encoded data, broken into lines.
 */
 public static String encodeLines (byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) {
 int blockLen = (lineLen*3) / 4;
 if (blockLen <= 0) throw new IllegalArgumentException();
 int lines = (iLen+blockLen-1) / blockLen;
 int bufLen = ((iLen+2)/3)*4 + lines*lineSeparator.length();
 StringBuilder buf = new StringBuilder(bufLen);
 int ip = 0;
 while (ip < iLen) {
    int l = Math.min(iLen-ip, blockLen);
    buf.append (encode(in, iOff+ip, l));
    buf.append (lineSeparator);
    ip += l; }
 return buf.toString(); }
 
 /**
 * Encodes a byte array into Base64 format.
 * No blanks or line breaks are inserted in the output.
 * @param in  An array containing the data bytes to be encoded.
 * @return    A character array containing the Base64 encoded data.
 */
 public static char[] encode (byte[] in) {
 return encode(in, 0, in.length); }
 
 /**
 * Encodes a byte array into Base64 format.
 * No blanks or line breaks are inserted in the output.
 * @param in    An array containing the data bytes to be encoded.
 * @param iLen  Number of bytes to process in <code>in</code>.
 * @return      A character array containing the Base64 encoded data.
 */
 public static char[] encode (byte[] in, int iLen) {
 return encode(in, 0, iLen); }
 
 /**
 * Encodes a byte array into Base64 format.
 * No blanks or line breaks are inserted in the output.
 * @param in    An array containing the data bytes to be encoded.
 * @param iOff  Offset of the first byte in <code>in</code> to be processed.
 * @param iLen  Number of bytes to process in <code>in</code>, starting at <code>iOff</code>.
 * @return      A character array containing the Base64 encoded data.
 */
 public static char[] encode (byte[] in, int iOff, int iLen) {
 int oDataLen = (iLen*4+2)/3;       // output length without padding
 int oLen = ((iLen+2)/3)*4;         // output length including padding
 char[] out = new char[oLen];
 int ip = iOff;
 int iEnd = iOff + iLen;
 int op = 0;
 while (ip < iEnd) {
    int i0 = in[ip++] & 0xff;
    int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
    int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
    int o0 = i0 >>> 2;
    int o1 = ((i0 &   3) << 4) | (i1 >>> 4);
    int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
    int o3 = i2 & 0x3F;
    out[op++] = map1[o0];
    out[op++] = map1[o1];
    out[op] = op < oDataLen ? map1[o2] : '='; op++;
    out[op] = op < oDataLen ? map1[o3] : '='; op++; }
 return out; }
 
 /**
 * Decodes a string from Base64 format.
 * No blanks or line breaks are allowed within the Base64 encoded input data.
 * @param s  A Base64 String to be decoded.
 * @return   A String containing the decoded data.
 * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
 */
 public static String decodeString (String s) {
 return new String(decode(s)); }
 
 /**
 * Decodes a byte array from Base64 format and ignores line separators, tabs and blanks.
 * CR, LF, Tab and Space characters are ignored in the input data.
 * This method is compatible with <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>.
 * @param s  A Base64 String to be decoded.
 * @return   An array containing the decoded data bytes.
 * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
 */
 public static byte[] decodeLines (String s) {
 char[] buf = new char[s.length()];
 int p = 0;
 for (int ip = 0; ip < s.length(); ip++) {
    char c = s.charAt(ip);
    if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
       buf[p++] = c; }
 return decode(buf, 0, p); }
 
 /**
 * Decodes a byte array from Base64 format.
 * No blanks or line breaks are allowed within the Base64 encoded input data.
 * @param s  A Base64 String to be decoded.
 * @return   An array containing the decoded data bytes.
 * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
 */
 public static byte[] decode (String s) {
 return decode(s.toCharArray()); }
 
 /**
 * Decodes a byte array from Base64 format.
 * No blanks or line breaks are allowed within the Base64 encoded input data.
 * @param in  A character array containing the Base64 encoded data.
 * @return    An array containing the decoded data bytes.
 * @throws    IllegalArgumentException If the input is not valid Base64 encoded data.
 */
 public static byte[] decode (char[] in) {
 return decode(in, 0, in.length); }
 
 /**
 * Decodes a byte array from Base64 format.
 * No blanks or line breaks are allowed within the Base64 encoded input data.
 * @param in    A character array containing the Base64 encoded data.
 * @param iOff  Offset of the first character in <code>in</code> to be processed.
 * @param iLen  Number of characters to process in <code>in</code>, starting at <code>iOff</code>.
 * @return      An array containing the decoded data bytes.
 * @throws      IllegalArgumentException If the input is not valid Base64 encoded data.
 */
 public static byte[] decode (char[] in, int iOff, int iLen) {
 if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4.");
 while (iLen > 0 && in[iOff+iLen-1] == '=') iLen--;
 int oLen = (iLen*3) / 4;
 byte[] out = new byte[oLen];
 int ip = iOff;
 int iEnd = iOff + iLen;
 int op = 0;
 while (ip < iEnd) {
    int i0 = in[ip++];
    int i1 = in[ip++];
    int i2 = ip < iEnd ? in[ip++] : 'A';
    int i3 = ip < iEnd ? in[ip++] : 'A';
    if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
       throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
    int b0 = map2[i0];
    int b1 = map2[i1];
    int b2 = map2[i2];
    int b3 = map2[i3];
    if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
       throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
    int o0 = ( b0       <<2) | (b1>>>4);
    int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
    int o2 = ((b2 &   3)<<6) |  b3;
    out[op++] = (byte)o0;
    if (op<oLen) out[op++] = (byte)o1;
    if (op<oLen) out[op++] = (byte)o2; }
 return out; }
 
 //Dummy constructor.
 private Base64Coder() {}

} 

La siguiente clase sería la clase utilitaria para generar el valor String del objeto y para volver a construir el objeto a partir del valor serializado.

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

/**
* Utility class to serialize and unserialize objects.
* @author gsolano
*
*/
public class ObjectSerializationUtils { 
  
 /**
  * Gets a String value of the object's serialize value.
  * @param object
  * @return
  * @throws IOException
  */
 public static String serializeObject(Serializable object) throws IOException {
       ByteArrayOutputStream baos = new ByteArrayOutputStream();
       ObjectOutputStream oos = new ObjectOutputStream( baos );
       oos.writeObject( object );
       oos.close();
       return new String( Base64Coder.encode( baos.toByteArray() ) );
   }
 
 /**
  * Rebuilds an object (unserializes) from the serialize String value.
  * @param serializeString
  * @return
  * @throws IOException
  * @throws ClassNotFoundException
  */
   public static Object unserializeObject( String serializeString )
      throws IOException , ClassNotFoundException {
         byte [] data = Base64Coder.decode( serializeString );
         ObjectInputStream ois = new ObjectInputStream(
              new ByteArrayInputStream(  data ) );
         Object o  = ois.readObject();
         ois.close();
         return o;
   }
}

Una sencilla prueba:

import java.io.Serializable;

public class MySerializeClass implements Serializable{

 private static final long serialVersionUID = 5021383691938311325L;
 
 protected String fooValue;

 public String getFooValue() {
  return fooValue;
 }

 public void setFooValue(String fooValue) {
  this.fooValue = fooValue;
 }
}

import java.io.IOException;

public class StringSerializationTest {
 
 public static void main(String[] args) {
  MySerializeClass mySerializeClass = new MySerializeClass();
  mySerializeClass.setFooValue("I will be turned in a string soon...");
  
  try {
   String DNACode = ObjectSerializationUtils.serializeObject(mySerializeClass);
   System.out.println(DNACode);   
   MySerializeClass clon = (MySerializeClass)
     ObjectSerializationUtils.unserializeObject(DNACode);
   System.out.println(clon.getFooValue());
   
  } catch (IOException e) {   
   e.printStackTrace();
  }
   catch (ClassNotFoundException e) {  
   e.printStackTrace();
  }  
 }
}

Salida:

rO0ABXNyABBNeVNlcmlhbGl6ZUNsYXNzRa+J3QbsLJ0CAAFMAAhmb29WYWx1ZXQAEkxqYXZhL2xhbmcvU3RyaW5nO3hwdAAkSSB3aWxsIGJlIHR1cm5lZCBpbiBhIHN0cmluZyBzb29uLi4u
I will be turned in a string soon...