code: public static OutputStreamWriter getWriter(OutputStream out, Charset charset) {
  		if (null == out) {
  			return null;
  		}
  
  		if (null == charset) {
  			return new OutputStreamWriter(out);
  		} else {
  			return new OutputStreamWriter(out, charset);
  		}
  	}
docs: 获得一个Writer
  
  @param out 输入流
  @param charset 字符集
  @return OutputStreamWriter对象