Develop Reference

java httpServer Post request work

I'm start learning java programming, and I want make a simple server application. I read about com.sun.net.httpserver.HttpServer and find a good example on this link: https://github.com/imetaxas/score-board-httpserver-corejava.
I understand how to do Get-request in url, but I don't know how POST works. I think it must be sent a form or data on the server.
I attach the link of project, which I'm learning, in readme the author wrote http://localhost:8081/2/score?sessionkey=UICSNDK - it's not working...
I wrote in url and get sessionkey: "localhost:8081/4711/login --> UICSNDK"
I wrote in url this for Post request: "localhost:8081/2/score?sessionkey=UICSNDK" - not working and in chrome return 404 bad request
3.wrote in url this:"localhost:8081/2/highscorelist"
Please help me, I am beginner.

The difference between GET and POST is that with a GET request the data you wish to pass to the endpoint is done by modifying the url itself by adding parameters to it.
With a POST any data you wish to send to the endpoint must be in the body of the request.
The body of a request is arbitrary data that comes after a blank line in the header The reqiest has the request line, following by any number of header attributes, then a blank line.
The server would need to know what the format of the body of the request was and parse it as appropriate.
Of course 'modern' frameworks like jax-rs allow you to automatically convert request data to objects, so that it is much simpler.

Java Axis2 - Overriding HTTP Host Header

I need to override the HTTP "Host" Header value in a request sent using Axis2. The end goal is to send the HTTP request to a particular destination, while having the Host Header in the request read as something else.
I have looked this up and found that you can add custom headers, but the method used to do that will not allow you to override any.
http://axis.apache.org/axis2/java/core/api/org/apache/axis2/client/Options.html
Thanks!

Reading Jira Webhook POST data

I am trying to read Jira issue data using a webhook that posts the data to my servlet.
When I travserve the request parameters map, I don't find anything in it.
But the content lenght shows as "8876" which means webhook is sending the data. Somehow I am not able to read/retrieve the data in my servlet.
Also checked, content-type returns as "application/json".
Does anyone know how to read Jira webhook post data?

You have to read the response body, not the parameters map. For that purpose you can use
request.getInputStream();
or
request.getReader();
method.
PS: You can configure the web hook to post data to http://requestb.in/ so you can easily analyze the request parameters, the request body, the headers, etc.

Java - send HTTP POST request without downloading all the content

Is it possible to send HTTP POST request to a webserver and retrieve just headers of response or read just few bytes of the body, so the rest won't be downloaded at all (so it won't consume traffic)? If yes, how?
I know that there is a HEAD method for this, but I need to achieve it by POST method .. well, I am not sure if I need the POST method, I just need to post the data. Maybe if the webserver isn't secured well enough (it doesn't check what method it's used - it's just directly access the post data), is it possible to send "post data" by HEAD request?

There is no built-in HTTP mechanism for this, and HTTP HEAD requests do not allow content in the body. If however you are the one writing the server code then anything is possible.
If this is the case, I would suggest a URL parameter that triggers this behavior. For example:
POST /myURL - This would return the whole response
POST /myURL?body=minimal - Returns the reduced size response that you are looking for.
And you would have to code your server method to construct and return the appropriate response based on the URL parameter.

how to remove a header from URLConnection

I am talking to a file upload service that accepts post data, not form data. By default, java's HttpURLConnection sets the Content-Type header to application/x-www-form-urlencoded. this is obviously wrong if i'm posting pure data.
I (the client) don't know the content type. I don't want the Content-Type header set at all. the service has a feature where it will guess at the content type (based on the file name, reading some data from the file, etc).
How do I unset a header? There's no remove header, and setting it to null doesn't change the value and setting it to the empty string results in the header being set with no value.

I haven't tested this approach but you can try this:
Extend HttpURLConnection and try by overriding its getContentHandler() and setContentHandler(...) methods. Most probably this should work as, you will take a look at code of getContentHandler().

Use Apache HttpClient instead of URLConnection
Use fluent Request to generate your request
use removeHeader()

What do you mean "i don't want the Content-Type header to set at all"?
The browser (or other http client) sends your post request to the server, so it has to inform the server which way it encoded the parameters.
If the Content-Type header is not set, on the server side you (= your server) won't be able to understand how to parse the received data.
If you didn't set Content-Type, the default value will be used.
You browser (or other http client) MUST do two things:
Send key/value pairs.
Inform the server how the key/value pairs were encoded.
So, it is impossible to completely get rid of this header.

I just accomplished this by setting the header to null.
connection.setRequestProperty(MY_HEADER, null);