encoder function for multipart/form-data in groovy

问题

I need to form a 'multipart/form-data' REST request with jpeg image and JSON file as the content.I am stuck with encoding the 'multipart/form-data' as a zip file.

Can someone tell me, how I can achieve this with groovy RESTClient? I could not find any documentation regarding this.

回答1:

As it can be seen in the docs RESTClient extends HTTPBuilder. HTTPBuilder has a getEncoder method that can be used to add dedicated encoder (with type and method). See the following piece of code:

import org.codehaus.groovy.runtime.MethodClosure
import javax.ws.rs.core.MediaType

//this part adds a special encoder    
def client = new RESTClient('some host')
client.encoder.putAt(MediaType.MULTIPART_FORM_DATA, new MethodClosure(this, 'encodeMultiPart'))

//here is the method for the encoder added above
HttpEntity encodeMultiPart(MultipartBody body) {
    MultipartEntityBuilder.create()
    .addBinaryBody(
        'file', 
        body.file, 
        ContentType.MULTIPART_FORM_DATA, 
        body.filename
    ).build()
}

//here's how MultipartBody class looks:
class MultipartBody {
   InputStream file
   String filename
}

Now to create a multipart request You need to pass an instance of MultipartBody as a body argument to the request.

回答2:

Realise this is an oldy but might help others, although the question answers it from a beginner point of view it is difficult to fully understand how to reuse all of above properly.

Firstly the last comment on the question points to this link :

Which attempts to re-use the answer incorrectly. It has mixed above answer with an answer from this link

def content1 = new ContentDisposition("filename=aa.json")
    def json1 = new File("resources/aa.json")
    def attachments1 = new Attachment("root", new ByteArrayInputStream(json1.getBytes()), content1)
    InputStream is2 = getClass().getResourceAsStream("resources/aa.json");
    InputStream is1 = getClass().getResourceAsStream("resources/img.png");
    ContentDisposition content2 = new ContentDisposition("attachment;filename=img.png")
    Attachment attachments2 = new Attachment("root1", is1, content2)
    def attachments = [attachments1, attachments2]
    def body1 = new MultipartBody(attachments)
    def client = new RESTClient( "https://somehost.com" )
    ocutag.encoder.putAt(MediaType.MULTIPART_FORM_DATA, new MethodClosure(this, 'encodeMultiPart1'))
    ocutag.encoder.putAt(MediaType.MULTIPART_FORM_DATA, new MethodClosure(this, 'encodeMultiPart2'))

The above is never going to work, I have it working like so:

def http = new RESTClient('http://localhost:8080')
http.encoder.putAt(MediaType.MULTIPART_FORM_DATA, new MethodClosure(this, 'encodeMultiPart'))
def body1 = new MultipartBody()   //This is that MultipartBody class in the first answer example not the one from your imports......
body1.file=file.getInputStream()
body1.filename=file.name
def response = http.put( path: url, body:body1, query:['query':action, ], requestContentType: 'multipart/form-data' )

You also have encodeMultiPart2 and encodeMultiPart1, I think this is a misunderstanding just reuse 1 declaration of this method in both cases.. you don't need to do none of the attachments etc you have in your example..

回答3:

Encoder registrations are so messy in previous responses, here is my working example:

import org.apache.cxf.jaxrs.ext.multipart.Attachment
import org.apache.cxf.jaxrs.ext.multipart.ContentDisposition
import org.apache.cxf.jaxrs.ext.multipart.MultipartBody
import org.apache.http.entity.ContentType
import org.apache.http.entity.mime.MultipartEntityBuilder
import javax.ws.rs.core.MediaType 

...

def filenameToUpload = "doggo.jpg"
def expectedRequestParamName = "file"

def static uploadFile() {
    // create attachment
    def fileToUpload = new File(filenameToUpload)
    def attachment = new Attachment(expectedRequestParamName, new ByteArrayInputStream(fileToUpload.getBytes()), new ContentDisposition("filename=" + filenameToUpload))
    def body = new MultipartBody(attachment)

    // create REST client
    def httpClient = new RESTClient('http://localhost:8080')

    // register encoder
    httpClient.encoder.putAt(MediaType.MULTIPART_FORM_DATA, customMultipartEncoder)

    // call REST
    httpClient.post(
        path: "upload",
        body: body,
        requestContentType: MediaType.MULTIPART_FORM_DATA)
}

// register multipart encoder
private def static customMultipartEncoder = { body ->
    def builder = MultipartEntityBuilder.create()

    body.allAttachments.collect {
        builder.addBinaryBody(
            it.contentId,
            it.dataHandler.inputStream,
            ContentType.MULTIPART_FORM_DATA,
            it.contentId) }

    return builder.build()
}

来源：https://stackoverflow.com/questions/28870172/encoder-function-for-multipart-form-data-in-groovy