播放2.0.4文件上传。 NullPointerException：null [英] Play 2.0.4 file upload. NullPointerException: null

问题描述

我在Java中使用Play，并且处理文件上传时遇到问题。

我做了一切像这个页面，但当我提交表单时，我得到 NullPointerException

这是我的表单： >

  @form（action = routes.Application.upload，'enctype  - >multipart / form-data）{
< input type =filename =picture> 
< p> 
< input type =submit> 
< / p> 
 
 $ / code> 

路线：



 POST / upload controllers.Application.upload（）
  

是我的控制器：

  import play.mvc.Http.MultipartFormData; 
 import play.mvc.Http.MultipartFormData.FilePart; 
 $ b public static Result upload（）{
 MultipartFormData body = request（）。body（）。asMultipartFormData（）; 
 FilePart picture = body.getFile（picture）; //这里我得到了NullPointerException 
 if（picture！= null）{
 String fileName = picture.getFilename（）; 
 String contentType = picture.getContentType（）; 
档案file = picture.getFile（）; 
 return ok（File uploaded）; 
} else {
 flash（error，Missing file）; 
返回重定向（routes.Application.index（））; 
 
 
 $ / code $ / pre 
 
我已经尝试过两种解决方案但没有人帮助我。 
 
 
 
我该如何解决这个问题？    请记住，  NullExceptions 在这个地方是 body 不是图片 
 
 
 
唯一可能的原因是您使用的HTML表单没有发送 enctype =multipart / form-data（也许你没有在浏览器中刷新表单，仍然试图发送一个正常的表单？）
 
 
请确保（在您的浏览器中），该页面
 < form action =/ uploadmethod = POSTenctype =multipart / form-data> 
 
< input type =filename =picture> 
 
< p> 
< input type =submit> 
< / p> 
 
< / form> 
  
 
I'm using Play in Java and I have problem with Handling file upload. 

I made everything like on this page but I get NullPointerException when I submit the form.

Here is my form:
@form(action = routes.Application.upload, 'enctype -> "multipart/form-data") {
<input type="file" name="picture">
    <p>
       <input type="submit">
   </p>
}
Route:
POST    /upload         controllers.Application.upload()
Here is my controller:
import play.mvc.Http.MultipartFormData;
import play.mvc.Http.MultipartFormData.FilePart;

public static Result upload() {
    MultipartFormData body = request().body().asMultipartFormData();
    FilePart picture = body.getFile("picture");  //here i got NullPointerException
    if (picture != null) {
        String fileName = picture.getFilename();
        String contentType = picture.getContentType(); 
        File file = picture.getFile();
        return ok("File uploaded");
    } else {
        flash("error", "Missing file");
        return redirect(routes.Application.index());    
    }
}
I've tried couple of solutions found on the Internet but none of them helped me. 

How can I fix it?
解决方案
Keep in mind that NullExceptions in this place is for body  not for picture

The only possible reason is that you are sending it with HTML form which hasn't enctype="multipart/form-data" (maybe you didn't refresh the form in the browser and still trying to send a normal form?)

make sure (in your browser), that page where you're filling the form has this form declaration and try again.
<form action="/upload" method="POST" enctype="multipart/form-data">

    <input type="file" name="picture">

    <p>
        <input type="submit">
    </p>

</form>


                        
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