BeanDeserializer.java

/*
 * Copyright (c) 2001-2008 Caucho Technology, Inc.  All rights reserved.
 *
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Caucho Technology (http://www.caucho.com/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "Burlap", "Resin", and "Caucho" must not be used to
 *    endorse or promote products derived from this software without prior
 *    written permission. For written permission, please contact
 *    info@caucho.com.
 *
 * 5. Products derived from this software may not be called "Resin"
 *    nor may "Resin" appear in their names without prior written
 *    permission of Caucho Technology.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL CAUCHO TECHNOLOGY OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @author Scott Ferguson
 */

package com.caucho.hessian.io;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;

/**
 * Serializing an object for known object types.
 */
public class BeanDeserializer extends AbstractMapDeserializer {
  private Class _type;
  private HashMap _methodMap;
  private Method _readResolve;
  private Constructor _constructor;
  private Object []_constructorArgs;
  
  public BeanDeserializer(Class cl)
  {
    _type = cl;
    _methodMap = getMethodMap(cl);

    _readResolve = getReadResolve(cl);

    Constructor []constructors = cl.getConstructors();
    int bestLength = Integer.MAX_VALUE;
    
    for (int i = 0; i < constructors.length; i++) {
      if (constructors[i].getParameterTypes().length < bestLength) {
        _constructor = constructors[i];
        bestLength = _constructor.getParameterTypes().length;
      }
    }

    if (_constructor != null) {
      _constructor.setAccessible(true);
      Class []params = _constructor.getParameterTypes();
      _constructorArgs = new Object[params.length];
      for (int i = 0; i < params.length; i++) {
        _constructorArgs[i] = getParamArg(params[i]);
      }
    }
  }

  public Class getType()
  {
    return _type;
  }
    
  public Object readMap(AbstractHessianInput in)
    throws IOException
  {
    try {
      Object obj = instantiate();

      return readMap(in, obj);
    } catch (IOException e) {
      throw e;
    } catch (Exception e) {
      throw new IOExceptionWrapper(e);
    }
  }
    
  public Object readMap(AbstractHessianInput in, Object obj)
    throws IOException
  {
    try {
      int ref = in.addRef(obj);

      while (! in.isEnd()) {
        Object key = in.readObject();
        
        Method method = (Method) _methodMap.get(key);

        if (method != null) {
          Object value = in.readObject(method.getParameterTypes()[0]);
	  
          method.invoke(obj, new Object[] {value });
        }
        else {
          Object value = in.readObject();
        }
      }
      
      in.readMapEnd();

      Object resolve = resolve(obj);

      if (obj != resolve)
	in.setRef(ref, resolve);

      return resolve;
    } catch (IOException e) {
      throw e;
    } catch (Exception e) {
      throw new IOExceptionWrapper(e);
    }
  }

  private Object resolve(Object obj)
  {
    // if there's a readResolve method, call it
    try {
      if (_readResolve != null)
        return _readResolve.invoke(obj, new Object[0]);
    } catch (Exception e) {
    }

    return obj;
  }

  protected Object instantiate()
    throws Exception
  {
    return _constructor.newInstance(_constructorArgs);
  }

  /**
   * Returns the readResolve method
   */
  protected Method getReadResolve(Class cl)
  {
    for (; cl != null; cl = cl.getSuperclass()) {
      Method []methods = cl.getDeclaredMethods();
      
      for (int i = 0; i < methods.length; i++) {
	Method method = methods[i];

	if (method.getName().equals("readResolve") &&
	    method.getParameterTypes().length == 0)
	  return method;
      }
    }

    return null;
  }

  /**
   * Creates a map of the classes fields.
   */
  protected HashMap getMethodMap(Class cl)
  {
    HashMap methodMap = new HashMap();
    
    for (; cl != null; cl = cl.getSuperclass()) {
      Method []methods = cl.getDeclaredMethods();
      
      for (int i = 0; i < methods.length; i++) {
	Method method = methods[i];

	if (Modifier.isStatic(method.getModifiers()))
	  continue;

	String name = method.getName();

	if (! name.startsWith("set"))
	  continue;

	Class []paramTypes = method.getParameterTypes();
	if (paramTypes.length != 1)
	  continue;

	if (! method.getReturnType().equals(void.class))
	  continue;

	if (findGetter(methods, name, paramTypes[0]) == null)
	  continue;

	// XXX: could parameterize the handler to only deal with public
	try {
	  method.setAccessible(true);
	} catch (Throwable e) {
	  e.printStackTrace();
	}
    
	name = name.substring(3);

	int j = 0;
	for (; j < name.length() && Character.isUpperCase(name.charAt(j)); j++) {
	}

	if (j == 1)
	  name = name.substring(0, j).toLowerCase() + name.substring(j);
	else if (j > 1)
	  name = name.substring(0, j - 1).toLowerCase() + name.substring(j - 1);


	methodMap.put(name, method);
      }
    }

    return methodMap;
  }

  /**
   * Finds any matching setter.
   */
  private Method findGetter(Method []methods, String setterName, Class arg)
  {
    String getterName = "get" + setterName.substring(3);
    
    for (int i = 0; i < methods.length; i++) {
      Method method = methods[i];

      if (! method.getName().equals(getterName))
	continue;
      
      if (! method.getReturnType().equals(arg))
	continue;

      Class []params = method.getParameterTypes();

      if (params.length == 0)
	return method;
    }

    return null;
  }

  /**
   * Creates a map of the classes fields.
   */
  protected static Object getParamArg(Class cl)
  {
    if (! cl.isPrimitive())
      return null;
    else if (boolean.class.equals(cl))
      return Boolean.FALSE;
    else if (byte.class.equals(cl))
      return Byte.valueOf((byte) 0);
    else if (short.class.equals(cl))
      return Short.valueOf((short) 0);
    else if (char.class.equals(cl))
      return Character.valueOf((char) 0);
    else if (int.class.equals(cl))
      return Integer.valueOf(0);
    else if (long.class.equals(cl))
      return Long.valueOf(0);
    else if (float.class.equals(cl))
      return Double.valueOf(0);
    else if (double.class.equals(cl))
      return Double.valueOf(0);
    else
      throw new UnsupportedOperationException();
  }
}