java|multipart/form-data中boundary的作用测试工具|postman

主要用于分割key-value对，多个kv之间使用boundary来进行分割
参考自：
【java|multipart/form-data中boundary的作用】https://stackoverflow.com/questions/3508338/what-is-the-boundary-in-multipart-form-data#:~:text=multipart%2Fform%2Ddata%20contains%20boundary,type%20of%20a%20request%20header.

multipart/form-data contains boundary to separate name/value pairs. The boundary acts like a marker of each chunk of name/value pairs passed when a form gets submitted. The boundary is automatically added to a content-type of a request header.
The form with enctype="multipart/form-data" attribute will have a request header Content-Type : multipart/form-data; boundary --- WebKit193844043-h (browser generated vaue).
The payload passed looks something like this:

Content-Type: multipart/form-data; boundary=---WebKitFormBoundary7MA4YWxkTrZu0gW-----WebKitFormBoundary7MA4YWxkTrZu0gW Content-Disposition: form-data; name=”file”; filename=”captcha” Content-Type:-----WebKitFormBoundary7MA4YWxkTrZu0gW Content-Disposition: form-data; name=”action”submit -----WebKitFormBoundary7MA4YWxkTrZu0gW--

On the webservice side, it's consumed in @Consumes("multipart/form-data") form.
Beware, when testing your webservice using chrome postman, you need to check the form data option(radio button) and File menu from the dropdown box to send attachment. Explicit provision of content-type as multipart/form-data throws an error. Because boundary is missing as it overrides the curl request of post man to server with content-type by appending the boundary which works fine.