springmvc 从session中和隐藏域中获取值

//添加跳转页面
@RequestMapping("/zhouyiContentAdd")
    public ModelAndView zhouyiContentAdd(ZhouyiContent zhouyiContent,@SessionAttribute("authorId") Integer authorId){
        ModelAndView mv = new ModelAndView();
        //因为保存成功后，继续跳转到本页，所以内容清空。非常例。
        zhouyiContent.setContent(null);  
        zhouyiContent.setInfo(null);
        zhouyiContent.setTuan(null);
        zhouyiContent.setXiang(null);
        //这一行是从页面自动封装成一个zhouyiAuthor的实体bean
        ZhouyiAuthor zhouyiAuthor = zhouyiContent.getZhouyiAuthor();
        
        if(zhouyiAuthor!=null) {
    //        System.out.println("zhouyiAuthor is ========: "+ zhouyiAuthor.toString());    
        mv.addObject("zhouyiAuthor",zhouyiAuthor);    
        }else {
    //        System.out.println("zhouyiAuthor is use session");
        mv.addObject("zhouyiAuthor", zhouyiAuthorService.getZhouyiContentAuthorById(authorId));
        }
        mv.addObject("zhouyiYao",zhouyiYaoService.getZhouyiYaos() );
        
        mv.setViewName("admin116/zhouyiContentAdd");
        return mv;
    }
    
//保存业务
    @RequestMapping("/zhouyiContentSave")
    public ModelAndView zhouyiContentSave(@Valid ZhouyiContent zhouyiContent,BindingResult errors,ZhouyiAuthor zhouyiAuthor) {
    ModelAndView mv = new ModelAndView();
        
        
        try {
            zhouyiContentService.addZhouyiContent(zhouyiContent);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            errors.addError(new FieldError("zhouyiContent", "info", "*事务一致性处理错误"));
        }
        if(errors.getErrorCount()>0) {
            for (FieldError err : errors.getFieldErrors()) {
                System.out.println(err.getField()+err.getDefaultMessage());
            }
            mv.addObject("tips", null);
            mv.addObject("errors", "*添加保存异常！");
            mv.addObject("zhouyiAuthor", zhouyiAuthor);
            mv.addObject("zhouyiYao",zhouyiYaoService.getZhouyiYaos() );
            mv.setViewName("admin116/zhouyiContentAdd");
            return mv;
        }
        mv.addObject("tips", zhouyiContent.getId()+"条，添加成功!");
        mv.setViewName("forward:/admin116/zhouyiContentAdd");
        
        return mv;
    }

<form:form  modelAttribute="zhouyiContent" class="form-horizontal" id="saveForm"  >

  <div class="form-group">
 
    <label for="zhouyiAuthor" class="col-sm-2 control-label">作者</label>
    <div class="col-sm-2">
    <input type="text" name="zhouyiAuthor.name" class="form-control" readonly="true" value="${zhouyiAuthor.name }"/>
    <form:hidden path="zhouyiAuthor.id" value="${zhouyiAuthor.id }"></form:hidden>
     
    </div>
  </div>
  
<div class="form-group">
    <label for="info" class="col-sm-2 control-label">爻</label>
    <div class="col-sm-6">
      <form:select path="zhouyiYao.id" class="form-control" id="zhouyiYao"   >
            <form:options items="${zhouyiYao}"  itemValue="id" itemLabel="extend"></form:options>
      </form:select>
    </div>
  </div>