针对Android里没有Arrays.CopyOf的解决办法

Arrays Copyprivate final <T> T[] copy(T[] source) {
   Class type = source.getClass().getComponentType();
   T[] target = (T[])Array.newInstance(type, source.length);
   System.arraycopy(source, 0, target, 0, source.length);
   return target;
}