文件保存方式，managed_file

//file 类型：http://xieyanxy9.iteye.com/admin/blogs/1953856
function weixin_other_parameters($form, $form_state) {
	$form['image_example_image_regist'] = array(
		'#title' => '宣传图  注册登录',
	    '#type' => 'managed_file',
	    '#upload_location' => 'public://weixin/',
	    '#default_value' => variable_get("hpgo_image_example_image_regist", ''),
	    '#upload_validators' => array(
			'file_validate_extensions' => array('png gif jpg jpeg'),
			'file_validate_image_resolutions' => array('620','240'),
		),
    );
	$form['submit'] = array(
        '#type' => 'submit',
        '#value' => '提交',
        '#submit' => array('weixin_other_parameters_submit')
    );

    return $form;

}

function weixin_other_parameters_submit($form, &$form_state) {
  if ($form_state['values']['image_example_image_regist'] != 0) {
		$file = file_load($form_state['values']['image_example_image_regist']);
		$file->status = FILE_STATUS_PERMANENT;
		file_save($file);
		file_usage_add($file, 'hpgo_weixin', 'sample_image', 1);
		variable_set('hpgo_image_example_image_regist', $file->fid);
	}
	// If the file was removed we need to remove the module's reference to the
	// removed file's fid, and remove the file.
	elseif ($form_state['values']['image_example_image_regist'] == 0) {
		// Retrieve the old file's id.
		$fid = variable_get('hpgo_image_example_image_regist', FALSE);
		$file = $fid ? file_load($fid) : FALSE;
		if ($file) {
			file_usage_delete($file, 'hpgo_weixin', 'sample_image', 1);
			file_delete($file);
		}
		variable_set('hpgo_image_example_image_regist', FALSE);
	}
}