classmapfinder.java

一个javabean的转换与copy非常的好用希望大家好好研究一下

/*
 * Copyright 2005-2007 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 net.sf.dozer.util.mapping.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import net.sf.dozer.util.mapping.fieldmap.ClassMap;


/**
 * @author tierney.matt
 * @author garsombke.franz
 */
public class ClassMapFinder {
  
  public ClassMap findClassMap(Map customMappings, Object sourceObj, Class destClass, String mapId, boolean isInstance) {
   ClassMap mapping = (ClassMap) customMappings.get(ClassMapKeyFactory.createKey(sourceObj.getClass(), destClass, mapId));
    
    // determine if it is an Interface or Abstract Class
    // iterate through the class maps and see if this class has any sub classes that are mapped to the source class OR
    // any of the source classes super classes
    // if we find a mapping don't even bother walking the tree
    if (mapping == null && !isInstance) {
      mapping = findInterfaceOrAbstractMapping(customMappings, destClass, sourceObj, mapId);
    }
    
    return mapping;
  }
  
  public List findInterfaceMappings(Map customMappings, Class sourceClass, Class destClass) {
    // If no existing cache entry is found, determine super type mapping and store in cache
    // Get interfaces
    Class[] sourceInterfaces = sourceClass.getInterfaces();
    Class[] destInterfaces = destClass.getInterfaces();
    List interfaceMaps = new ArrayList();

    for (int i = 0; i < destInterfaces.length; i++) {
      // see if the source class is mapped to the dest class
      ClassMap interfaceClassMap = (ClassMap) customMappings.get(ClassMapKeyFactory.createKey(sourceClass,
          destInterfaces[i]));
      if (interfaceClassMap != null) {
        interfaceMaps.add(interfaceClassMap);
      }
    }

    for (int i = 0; i < sourceInterfaces.length; i++) {
      // see if the source class is mapped to the dest class
      ClassMap interfaceClassMap = (ClassMap) customMappings.get(ClassMapKeyFactory.createKey(sourceInterfaces[i],
          destClass));
      if (interfaceClassMap != null) {
        interfaceMaps.add(interfaceClassMap);
      }
    }

    // multiple levels of custom mapping processed in wrong order - need to reverse
    Collections.reverse(interfaceMaps);

    return interfaceMaps;
  }  
  
  //TODO: what is logic difference between this method and checkForInterfaceMappingsInCustomMappings.  By the names
  //these methods seem to be trying to accomplish the same thing with a different implementation.  Also, one takes a map-id
  //and the other doesnt ??  somewhat confusing
  public ClassMap findInterfaceOrAbstractMapping(Map customMappings, Class destClass, Object sourceObj, String mapId) {
    ClassMap newClassMap = null;
    Class newClass = null;
    //Create a local copy of the custom mappings to avoid any rare thread synchronization issues while iterating
    //over the custom mappings.  See bug #1550275.
    Map localCustomMappings = new HashMap(customMappings);
    Iterator iter = localCustomMappings.keySet().iterator();
    while (iter.hasNext()) {
      ClassMap map = (ClassMap) localCustomMappings.get(iter.next());
      Class dest = map.getDestClass().getClassToMap();
      
      // is Assignable?
      // now that we have the a sub class for the abstract class or interface we need to
      // verify that the source class in the map IS a super class of the source object...or the source object itself.
      if (destClass.isAssignableFrom(dest)
          && (map.getSourceClass().getClassToMap().isAssignableFrom(sourceObj.getClass()) || map.getSourceClass()
              .getClassToMap().isInstance(sourceObj))
          // look for most specific mapping
          && (newClass == null || newClass.isAssignableFrom(dest))) {
        newClassMap = map;
        newClass = dest;
      }
    }
    return newClassMap;
  }
  
  
}