1, drupal_get_form,只要是准备$form_state['build_info']['arg'], 然后进入drupal_build_form(), 2, form build 主要有3步 drupal_retrieve_form, drupal_prepare_form, drupal_process_form, 3, 生成form array renderable --相对来说, drupal_retrieve_form 实现的比较直观, 就是把form id函数定义的数组取