public static final int writeJSONString(OutputStream os, // 
                                             Object object, // 
                                             SerializerFeature... features) throws IOException {
        return writeJSONString(os, object, DEFAULT_GENERATE_FEATURE, features);
    }
write object as json to OutputStream
@param os output stream
@param object
@param features serializer features
@since 1.2.11
@throws IOException
src/main/java/com/alibaba/fastjson/JSON.java