java 如何从带有 Jersey 的多部分表单中读取多个同名的（文件）输入？

Question

提问by toniedzwiedz

I have successfully developed a service, in which I read files uploaded in a multipart form in Jersey. Here's an extremely simplified version of what I've been doing:

我已经成功开发了一项服务，在该服务中我读取了泽西岛以多部分形式上传的文件。这是我一直在做的事情的一个极其简化的版本：

@POST
@Path("FileCollection")
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadFile(@FormDataParam("file") InputStream uploadedInputStream,
        @FormDataParam("file") FormDataContentDisposition fileDetail) throws IOException {
    //handle the file
}

This works just fine but I've been given a new requirement. In addition to the file I'm uploading, I have to handle an arbitrary number of resources. Let's assume these are image files.

这工作得很好，但我得到了一个新的要求。除了我正在上传的文件之外，我还必须处理任意数量的资源。让我们假设这些是图像文件。

I figured I'd just provide the client with a form with one input for the file, one input for the first image and a button to allow adding more inputs to the form (using AJAX or simply plain JavaScript).

我想我只是为客户端提供一个表单，其中包含一个文件输入、一个输入第一张图像和一个按钮以允许向表单添加更多输入（使用 AJAX 或简单的 JavaScript）。

<form action="blahblahblah" method="post" enctype="multipart/form-data">
   <input type="file" name="file" />
   <input type="file" name="image" />
   <input type="button" value="add another image" />
   <input type="submit"  />
</form>

So the user can append the form with more inputs for images, like this:

因此，用户可以为表单附加更多图像输入，如下所示：

<form action="blahblahblah" method="post" enctype="multipart/form-data">
   <input type="file" name="file" />
   <input type="file" name="image" />
   <input type="file" name="image" />
   <input type="file" name="image" />
   <input type="button" value="add another image" />
   <input type="submit"  />
</form>

I hoped it would be simple enough to read the fields with the same name as a collection. I've done it successfully with text inputs in MVC .NET and I thought it wouldn't be harder in Jersey. It turns out I was wrong.

我希望读取与集合同名的字段足够简单。我已经使用 MVC .NET 中的文本输入成功地完成了它，我认为在 Jersey 中它不会更难。事实证明我错了。

Having found no tutorials on the subject, I started experimenting.

没有找到有关该主题的教程，我开始尝试。

In order to see how to do it, I dumbed the problem down to simple text inputs.

为了了解如何做到这一点，我将问题简化为简单的文本输入。

<form action="blahblabhblah" method="post" enctype="multipart/form-data">
   <fieldset>
       <legend>Multiple inputs with the same name</legend>
       <input type="text" name="test" />
       <input type="text" name="test" />
       <input type="text" name="test" />
       <input type="text" name="test" />
       <input type="submit" value="Upload It" />
   </fieldset>
</form>

Obviously, I needed to have some sort of collection as a parameter to my method. Here's what I tried, grouped by collection type.

显然，我需要将某种集合作为我的方法的参数。这是我尝试过的，按集合类型分组。

Array

大批

At first, I checked whether Jersey was smart enough to handle a simple array:

起初，我检查 Jersey 是否足够聪明来处理一个简单的数组：

@POST
@Path("FileCollection")
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadFile(@FormDataParam("test") String[] inputs) {
    //handle the request
}

but the array wasn't injected as expected.

但阵列没有按预期注入。

MultiValuedMap

多值映射

Having failed miserably, I remembered that MultiValuedMapobjects could be handled out of the box.

惨遭失败后，我记得MultiValuedMap可以开箱即用地处理对象。

@POST
@Path("FileCollection")
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadFile(MultiValuedMap<String, String> formData) {
    //handle the request
}

but it doesn't work either. This time, I got an exception

但它也不起作用。这一次，我有一个例外

SEVERE: A message body reader for Java class javax.ws.rs.core.MultivaluedMap, 
and Java type javax.ws.rs.core.MultivaluedMap<java.lang.String, java.lang.String>, 
and MIME media type multipart/form-data; 
boundary=----WebKitFormBoundaryxgxeXiWk62fcLALU was not found.

I was told that this exception could be gotten rid of by including the mimepulllibrary so I added the following dependency to my pom:

有人告诉我，可以通过包含mimepull库来消除此异常，因此我在 pom 中添加了以下依赖项：

    <dependency>
        <groupId>org.jvnet</groupId>
        <artifactId>mimepull</artifactId>
        <version>1.3</version>
    </dependency>

Unfortunately the problem persists. It's probably a matter of choosing the right body reader and using different parameters for the generic. I'm not sure how to do this. I want to consume both file and text inputs, as well as some others (mostly Longvalues and custom parameter classes).

不幸的是，问题仍然存在。这可能是选择正确的正文阅读器并为泛型使用不同的参数的问题。我不知道该怎么做。我想同时使用文件和文本输入，以及其他一些（主要是Long值和自定义参数类）。

FormDataMultipart

表单数据多部分

After some more research, I found the FormDataMultiPartclass. I've successfully used it to extract the string values from my form

经过更多研究，我找到了FormDataMultiPart类。我已经成功地使用它从我的表单中提取字符串值

@POST
@Path("upload2")
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadMultipart(FormDataMultiPart multiPart){
    List<FormDataBodyPart> fields = multiPart.getFields("test");
    System.out.println("Name\tValue");
    for(FormDataBodyPart field : fields){
        System.out.println(field.getName() + "\t" + field.getValue());
        //handle the values
    }
    //prepare the response
}

The problem is, this is a solution to the simplified version of my problem. While I know that every single parameter injected by Jersey is created by parsing a string at some point (no wonder, it's HTTP after all) and I have some experience writing my own parameter classes, I don't really how to convert these fields to InputStreamor Fileinstances for further processing.

问题是，这是我问题的简化版本的解决方案。虽然我知道 Jersey 注入的每个参数都是通过在某个时候解析字符串创建的（难怪，毕竟它是 HTTP）并且我有一些编写自己的参数类的经验，但我真的不知道如何将这些字段转换为InputStream或File进一步处理的实例。

Therefore, before diving into Jersey source code to see how these objects are created, I decided to ask here whether there is an easier way to read a set (of unknown size) of files. Do you know how to solve this conundrum?

因此，在深入研究 Jersey 源代码以查看这些对象是如何创建的之前，我决定在这里询问是否有更简单的方法来读取一组（未知大小）文件。你知道如何解决这个难题吗？

Answer 1

回答by toniedzwiedz

I have found the solution by following the example with FormDataMultipart. It turns out I was very close to the answer.

我通过以下示例找到了解决方案FormDataMultipart。事实证明，我非常接近答案。

The FormDataBodyPartclass provides a method that allows its user to read the value as InputStream(or theoretically, any other class, for which a message body reader is present).

的FormDataBodyPart类提供一种方法，其允许其用户读取的值作为InputStream（或理论上，任何其他类，针对其消息体读取器存在的话）。

Here's the final solution:

这是最终的解决方案：

Form

形式

The form remains unchanged. I have a couple of fields with the same name, in which I can place files. It's possible to use both multipleform inputs (you want these when uploading many files from a directory) and numerous inputs that share a name (Flexible way to upload an unspecified number of files from different location). It's also possible to append the form with more inputs using JavaScript.

形式保持不变。我有几个同名的字段，我可以在其中放置文件。可以同时使用multiple表单输入（从目录上传许多文件时需要这些）和共享名称的大量输入（从不同位置上传未指定数量的文件的灵活方式）。还可以使用 JavaScript 为表单附加更多输入。

<form action="/files" method="post" enctype="multipart/form-data">
   <fieldset>
       <legend>Multiple inputs with the same name</legend>
       <input type="file" name="test" multiple="multiple"/>
       <input type="file" name="test" />
       <input type="file" name="test" />
   </fieldset>
   <input type="submit" value="Upload It" />
</form>

Service - using `FormDataMultipart`

服务 - 使用 `FormDataMultipart`

Here's a simplified method that reads a collection of files from a multipart form. All inputs with the same are assigned to a Listand their values are converted to InputStreamusing the getValueAsmethod of FormDataBodyPart. Once you have these files as InputStreaminstances, it's easy to do almost anything with them.

这是一种从多部分表单中读取文件集合的简化方法。具有相同的所有输入都分配给 aList并InputStream使用的getValueAs方法将它们的值转换为FormDataBodyPart。一旦您将这些文件作为InputStream实例，就可以轻松地对它们进行几乎任何操作。

@POST
@Path("files")
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadMultipart(FormDataMultiPart multiPart) throws IOException{        
    List<FormDataBodyPart> fields = multiPart.getFields("test");        
    for(FormDataBodyPart field : fields){
        handleInputStream(field.getValueAs(InputStream.class));
    }
    //prepare the response
}

private void handleInputStream(InputStream is){
    //read the stream any way you want
}

Answer 2

回答by Amit Sharma

@Path("/upload/multiples")
@POST
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Produces(MediaType.APPLICATION_JSON)
public Response uploadImage(@FormDataParam("image") List<FormDataBodyPart> imageDatas){
   for( FormDataBodyPart imageData : imageDatas ){
       // Your actual code.
       imageData.getValueAs(InputStream.class);
    }
}

Answer 3

回答by Blaskovicz

If anyone is trying to do generic type=textinput boxes with the same nameattribute like I was, you will be able to switch them to type=hiddeninputs and have that work as a @FormParam("inputName") List<String> nameListin your route.

如果有人像我type=text一样尝试使用具有相同name属性的通用输入框，您将能够将它们切换到type=hidden输入并使其@FormParam("inputName") List<String> nameList在您的路线中工作。

Obviously, when switching to hidden inputs the only point is to still send the data to the server without creating a UI element for it, so you will need to switch to an alternate display UI (for example, I used a button element for easy click-to-remove functionality).

显然，当切换到隐藏输入时，唯一的一点是仍然将数据发送到服务器而不为其创建 UI 元素，因此您将需要切换到备用显示 UI（例如，我使用按钮元素来轻松单击-删除功能）。

java 如何从带有 Jersey 的多部分表单中读取多个同名的（文件）输入？

提问by toniedzwiedz

Array

大批

MultiValuedMap

多值映射

FormDataMultipart

表单数据多部分

回答by toniedzwiedz

Form

形式

Service - using `FormDataMultipart`

服务 - 使用 `FormDataMultipart`

回答by Amit Sharma

回答by Blaskovicz

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标签

java 如何从带有 Jersey 的多部分表单中读取多个同名的（文件）输入？

提问by toniedzwiedz

Array

大批

MultiValuedMap

多值映射

FormDataMultipart

表单数据多部分

回答by toniedzwiedz

Form

形式

Service - using FormDataMultipart

服务 - 使用 FormDataMultipart

回答by Amit Sharma

回答by Blaskovicz

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最近更新

标签

Service - using `FormDataMultipart`

服务 - 使用 `FormDataMultipart`