//先获取本地资源引用名称，type name是R.drawable.background中的"drawable"，entry name是"background"
  String resTypeName = getContext().getResources().getResourceTypeName(id);
  String resEntryName = getContext().getResources().getResourceEntryName(id);
  //然后创建皮肤包所在应用的Context
  Context apk = getContext().createPackageContext(packageName,
      Context.CONTEXT_IGNORE_SECURITY)
  //然后就是获取皮肤包中的资源id了
  int drawavleId = apk.getResources().getIdentifier(resEntryName, resTypeName,
      apk.getPackageName());  

  private List<Integer> skinViewList = new ArrayList<Integer> ();  private void scanViewGroup(ViewGroup group, List<Integer> skinViewList, Resources res) {
    //first we need check if this ViewGroup have a background
    if(group.getId() != View.NO_ID
        && res.getResourceEntryName(group.getId()).contains(SKIN_PATTERN)
        && !skinViewList.contains(group)) {
      skinViewList.add(group.getId());
    }

    //second check its child view
    View child;

    for(int i = 0; i < group.getChildCount(); i++) {
      child = group.getChildAt(i);

      if(child instanceof ViewGroup) {
        scanViewGroup((ViewGroup)child, skinViewList, res);
      } else if(child.getId() == View.NO_ID) {
        return;
      } else {
        int viewId = child.getId();
        String entryName = res.getResourceEntryName(viewId);

        Log("scanViewGroup(), entryName of this childView : " + entryName);

        if(entryName.contains(SKIN_PATTERN) && !skinViewList.contains(child))
          skinViewList.add(child.getId());
      }
    }
  }

    //先判断前面扫描的skinViewList是否为空，不为空意味着有控件需要换肤
    if(skinViewList != null && skinViewList.size() > 0) {
      int viewId = -1, backgroundId = -1;
      for(int i = 0; i < attrs.getAttributeCount(); i++) {
        if(attrs.getAttributeName(i).equals("id")) {
          viewId = attrs.getAttributeResourceValue(i, -1);
        }

        if(attrs.getAttributeName(i).equals("background")) {
          backgroundId = attrs.getAttributeResourceValue(i, -1);
        }
      }

      //check if background drawable need save
      if(viewId != -1 && backgroundId != -1 &&
          drawableIdList != null && !drawableIdList.containsKey(viewId)) {
        drawableIdList.put(viewId, backgroundId);

        Log("add to drawableIdList, viewId = " + viewId
            + ", backgroundId = " + backgroundId);
      }
    }