collectionutils.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.lang.reflect.Array;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;

/**
 * @author tierney.matt
 * @author garsombke.franz
 */
public class CollectionUtils {
  
  public boolean isArray(Class aClass) {
    return aClass.isArray();
  }

  public boolean isCollection(Class aClass) {
    return Collection.class.isAssignableFrom(aClass);
  }

  public boolean isIterator(Class aClass) {
    return Iterator.class.isAssignableFrom(aClass);
  }
  
  public boolean isList(Class aClass) {
    return List.class.isAssignableFrom(aClass);
  }

  public boolean isSet(Class aClass) {
    return Set.class.isAssignableFrom(aClass);
  }

  public int getLengthOfCollection(Object value) {
    if (isArray(value.getClass())) {
      return Array.getLength(value);
    } else
    // is collection
    {
      Collection collectionTo = (Collection) value;
      return collectionTo.size();
    }
  }

  public Object getValueFromCollection(Object collection, int index) {
    if (isArray(collection.getClass())) {
      return Array.get(collection, index);
    } else
    // is collection
    {
      Collection collectionTo = (Collection) collection;

      return collectionTo.toArray()[index];
    }
  }
  
  public Set createNewSet(Class destType) {
    return createNewSet(destType, null);
  }

  public Set createNewSet(Class destType, Collection srcValue) {
    Set result = null;
    if (SortedSet.class.isAssignableFrom(destType)) {
      result = new TreeSet();
    } else {
      result = new HashSet();
    }
    if (srcValue != null) {
      result.addAll(srcValue);
    }
    return result;
  }
  
  public Object convertListToArray(List list, Class destEntryType) {
    Iterator iter = list.iterator();
    Object outArray = Array.newInstance(destEntryType, list.size());
    int count = 0;
    while (iter.hasNext()) {
      Object element = iter.next();
      Array.set(outArray, count, element);
      count++;
    }
    return outArray;
  }
}