public static List<DomElement> $(String selector, String content){
		
		//System.out.println(content);
		
		String[] selectors = selector.split("\\s");
		if(selectors.length==1){//单一的选择器模式
			return singleSelector(selectors[0], content);
		}else if(selectors.length==2){//子孙选择器模式，儿子，孙子，全有
			//先找出第一个选择器所满足的dom元素
			List<DomElement> domElements = singleSelector(selectors[0], content);
			List<DomElement> domElements2 = new ArrayList<DomElement>();
			for(DomElement domElement : domElements){
				domElements2.addAll(singleSelector(selectors[1], domElement.getHtml()));
			}
			return domElements2;
		}else if(selectors.length==3){//中间符号的选择器
			if(selectors[1].equals(">")){ //亲孩子
				
				//System.out.println(content.length());
				
				List<DomElement> domElements = singleSelector(selectors[0], content);
				//System.err.println(domElements.size());
				List<DomElement> domElements2 = new ArrayList<DomElement>();
				for(DomElement domElement : domElements){
					domElements2.addAll(findAllDirectChildrenAndSelect(domElement.getHtml(), selectors[2]));
				}
				return domElements2;
			}else if(selectors[1].equals("+")){//相邻同级tag，限定
				
			}else if(selectors[1].equals("~")){ //之后同级的tag，限定
				
			}
			
		}
		return null;
	}