Question

我正在尝试通过以JSON格式提供所需请求来使用邮递员提供服务：

 {
    "baseParam": {
        "userId": "u1234"
    },
    "resource": {
        "name": "resource"
    }
}

还有一个多部分文件，如下面的邮递员屏幕所示

Postman screen

但是我得到了错误：

'无法将类型'java.lang.String'的值转换为所需的类型'SampleRequestObject'；嵌套异常为java.lang.IllegalStateException：无法将[java.lang.String]类型的值转换为所需类型'

控制器

   @RequestMapping(method = RequestMethod.POST, value = "/sample/resource", 
   produces = "application/json")
   @ResponseBody
   public final ResponseObject sampleResource(@RequestParam("request") final 
   SampleRequestObject requestObject,@RequestParam("file") final 
   MultipartFile file,BindingResult result ) throws IOException {

   String success = “SUCCESS”;
   requestObject.setFile(file);
   String id=sampleService.sampleResourceService(resourceObject);   
   //sampleService Object has been autowired earlier in controller              
    return  success;                                                                                                       


    }  
    }

SampleRequestObject –模型类

    public class SampleRequestObject extends SampleMainObject {

    @NotNull
    @IsValid(baseParam = { "userId"})
    private BaseParam baseParam;

    @NotNull    
    private SampleResource resource;   // ANOTHER OBJECT OF SAMPLE RESOURCE 
                                          CLASS
    private MultipartFile file;

    public SampleResource getResource() {
    return resource;
    }

    public void setResource(SampleResource resource) {
    this.resource = resource;
    }

    @Override

    public Param getBaseParam() {

    return baseParam;
    }

    public final void setBaseParam(final BaseParam baseParam) {
    this.baseParam = baseParam;
    }

    public MultipartFile getFile() {
    return file;
    }

    public void setFile(MultipartFile file) {
    this.file = file;
    }   
    }

SampleServiceImpl.class中的函数（SampleService实现）

    @Override
    @Transactional
    public final String sampleResourceService( SampleRequestObject 
    requestObject) {throws IOException
    String Id=null;

    try
    {

    MainResourceObject resourceObject = new MainResourceObject();
    resourceObject.setActualName(requestObject.getFile()
    .getOriginalFilename());
    resourceObject.setName(requestObject.getResource().getName()); );   
        .
        .
        .
        .  
        .
        .
        .
        .  

        .  
    }
    catch (Exception e) {
    log.error("Service Execution failed",e);
    }
    }

我还尝试提供@ModelAttribute而不是@RequestParam。然后，可以输入控制器和服务，但是（在控制器中）requestObject的所有值都被填充为空值。因此，它将从服务实现中引发NullPointeException。

请提供解决方案。

Answer 1

您可以尝试

public final ResponseObject sampleResource(SampleRequestObject request,
       @RequestParam("file") final MultipartFile file,
       BindingResult result ) throws IOException {
...

我刚刚删除了@RequestParam并将变量更改为request

无法将类型“ java.lang.String”的值转换为所需的模型对象类型

1 个答案: