将JSON对象数组映射到@RequestBody List< T>使用杰克逊

问题描述

这里是收到的数据由控制器@RequestBody（使用正确的json requestheader发送）：

  [{name = tag1}，{name = tag2 }，{name = tag3}] 
  

这里是控制器：

  @RequestMapping（value =purchases / {purchaseId} / tags，method = RequestMethod.POST，params =manyTags） 
 @ResponseStatus（HttpStatus.CREATED）
 public void createAll（@PathVariable（purchaseId）final长期purchaseId，@RequestBody final List< Tag>实体）
 {
购买购买= purchaseService.getById（purchaseId）; 
 
设置< Tag> tags = purchase.getTags（）; 
 purchaseService.updatePurchase（购买）; 
} 
  

当我调试并查看实体值时，它显示为一个ArrayList通用对象，而不是我期望的'Tag'类型的对象列表。

如何获得杰克逊映射通过的数组对象的类型为'Tag'类型的列表？

谢谢 解决方案 List<？>标签。我不知道该怎么做才能完全解决这个问题（可能需要Spring集成团队的一些东西），但一个解决方法是定义自己的类型，如：

 静态类TagList扩展ArrayList< Tag> {} 
  

并改为使用它。这将通过超类型声明保留通用参数化，这样即使Spring只通过等价的 TagList.class ，杰克逊也可以计算出 Tag 参数。

I'm having issues using Jackson to map a Javascript posted JSON array of hashes (Tag).

Here is the data received by the controller @RequestBody (It is send with correct json requestheader):

[{name=tag1}, {name=tag2}, {name=tag3}]

Here is the controller:

@RequestMapping(value = "purchases/{purchaseId}/tags", method = RequestMethod.POST, params = "manyTags")
@ResponseStatus(HttpStatus.CREATED)
public void createAll(@PathVariable("purchaseId") final Long purchaseId, @RequestBody final List<Tag> entities)
{
        Purchase purchase = purchaseService.getById(purchaseId);

        Set<Tag> tags = purchase.getTags();
        purchaseService.updatePurchase(purchase);
    }

When I debug and view the 'entities' value it shows as an ArrayList of generic objects, not as a list of objects of type 'Tag' as I would expect.

How can I get jackson to map a passed array of objects to a list of obejcts of type 'Tag'?

Thanks

解决方案

It sounds like Spring is not passing full type information for some reason, but rather a type-erased version, as if declaration was something like List<?> tag. I don't know what can be done to fully resolve this (may need something from Spring integration team), but one work-around is to define your own type like:

static class TagList extends ArrayList<Tag> { }

and use that instead. This will retain generic parameterization through super-type declarations so that even if Spring only passes equivalent of TagList.class, Jackson can figure out the Tag parameter.

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