Groovy中的类抛出异常 [英] Class cast exception in Groovy

问题描述

我想用grails上的groovy上传图片。
我的gsp页面如下（我正在展示原件的简化版本）

 < g：form controller =postaction =saveenctype =multipart / form-data> 
我的照片< input type =filename =myPicture/> 
< g：submitButton name =submitvalue =Save/> 
< / g：表格> 
  

我的域名类如下：

 class Post {
 
 byte [] myPicture 
 
 static mapping = {
 myPicture类型：blob
} 
  

我需要这个映射，否则MySql会创建一个smallblob， / p>

 静态约束= {
 myPicture（可空值：false）
} 
 
 } 
  

在控制器中，我有一个名为save的动作，如下所示：

  def save = {
 def post = loadPost（params.id）
 
 post.properties = params 
 
 if（post.save（））{
 printhallo world
 redirect（action：'list'，params：params）
} else {
渲染（view：'edit'，model：[post：post]）
} 
} 
  

当我尝试t时抛出异常将图像保存在数据库中。

  2009-04-27 18：16：07,319 [20806951 @ qtp0-0]错误errors.GrailsExceptionResolver  -  java.lang.ClassCastException：[B不能转换为java.sql.Blob 
  

org.codehaus.groovy.runtime.InvokerInvocationException：java.lang.ClassCastException：[B不能转换为java.sql.Blob

任何提示为什么会这样？

顺便说一句，我在一个教程中看到图像是作为字符串处理的，但它也不能用
。

  def save = {$ b解析方案


$ b def post = loadPost（params.id）

def f = request.getFile（'myPicture'）

post.myPicture = f.getBytes（ ）
post.pictureType = f.getContentType（）


if（post.save（））{


I want to upload an image using a groovy on grails. My gsp page is as follows (I am showing a simplified version of the original)

<g:form controller="post" action="save" enctype="multipart/form-data">        
      My picture  <input type="file" name="myPicture" />     
    <g:submitButton name="submit" value="Save"/>
</g:form>

My domain class is as follows:

class Post {    

byte[] myPicture

static mapping = {
    myPicture type:  "blob" 
}

I need this mapping otherwise MySql will create a smallblob which is to small to fit the images

static constraints = {
    myPicture(nullable:false)      
}

}

At the controller I have an action called save which is as follows:

def save = {                               
    def post = loadPost(params.id)

    post.properties = params

    if(post.save()) {
        print "hallo world"             
        redirect(action:'list', params:params)
    } else {
        render(view:'edit', model:[post:post])
    }
}

The exception is thrown when I try to save the image at the DB.

2009-04-27 18:16:07,319 [20806951@qtp0-0] ERROR errors.GrailsExceptionResolver  - java.lang.ClassCastException: [B cannot be cast to java.sql.Blob

org.codehaus.groovy.runtime.InvokerInvocationException: java.lang.ClassCastException: [B cannot be cast to java.sql.Blob

Any hint why is this?

BTW, I've seen in a tutorial that images were handled as strings but it didn't work as well.

解决方案

try this way:

  def save = {                               

    def post = loadPost(params.id)

    def f = request.getFile('myPicture')             

    post.myPicture = f.getBytes()
    post.pictureType = f.getContentType()                    


    if(post.save()) {

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