Develop Reference

Java httpservlet and routing. How starting?

my boss asked me to develop an webservice that should work in this matter:
an external app contact my app and:
if the method used is GET and the url contacted is:
http://localhost:8080/webapp/webservice/?findall
will return all rows find in a table;
If the same external app contact my app in the same method but send a key and a value like:
http://localhost:8080/webapp/webservice/?field1=value1
my app will return a set of rows filtered by field/value.
And soon on with with any method sending request and with other fields.
I know how do the operations using JPA 2.1 but how mapping the actions?
Someone could help me to starting in the right direction with JDK1.8?

Java Web Start return value - workaround

I know that returning a value from a JWSapp to the "calling" page cannot be done.
However, I use this JWSapp to get user ID from its biometric information.
The idea is that when you try to login, a button allows to launch the JWSapp that will deal with the biometric tasks and then return the user's idea.
Still, as I said, from a JWSapp I cannot send back the id to auto-complete the field. I found this post: Returning a value from a java web start application but I really need to keep the JWS (external constraints)...
So there's my question: is there any workaround to get the id back?
Thank you in advance :)

How do you set up a redirect from www to non-www with Play! Java 2.3 running the default server?

I recently set up a website and pushed it to production using Digital Ocean. However, I noticed that for both SEO purposes and to make Facebook Share work appropriately, I should set up my server to redirect www. requests to non-www. I'm running Play! Java 2.3 with a PostgreSQL database and the default Netty server. Any advice would be greatly appreciated.

There are lots of ways of redirecting. I wouldn't say DNS-redirects are the correct and only way of doing it, it's one way. Google is just fine with you doing a 301 redirect with Play.
Here's one way of accomplishing it with Play! filters (scala):
object NonWwwFilter extends Filter {
def apply(f:RequestHeader => Future[Result])(rh: RequestHeader): Future[Result] =
if (rh.host.startsWith("www.")) {
Future.successful(Results.MovedPermanently("https://" + rh.host.substring(4) + rh.uri))
} else {
f(rh)
}
}

The right way to do it is to do in not on the framework/webserver side, but on the DNS-server side.
You can do it in DNS-management area of GoDaddy or any other domain name registrar.

ADAL 4 Android not passing client secret

I'll first say that I'm sure it is just me since people have probably got this to work out of the box without having to edit the ADAL 4 Android Library without editing the source.
When running the sample program and authenticating with a token I get an error from AZURE that it is not passing the client_secret in the message body. I can confirm that this is in fact the case - it is not passing the client_secret.
Although if I edit the OAuth2.java file and change the method buildTokenRequestMessage to something like the following the workflow works perfectly
public String buildTokenRequestMessage(String code) throws UnsupportedEncodingException {
String message = String.format("%s=%s&%s=%s&%s=%s&%s=%s&%s=%s",
AuthenticationConstants.OAuth2.GRANT_TYPE,
StringExtensions.URLFormEncode(AuthenticationConstants.OAuth2.AUTHORIZATION_CODE),
AuthenticationConstants.OAuth2.CODE, StringExtensions.URLFormEncode(code),
AuthenticationConstants.OAuth2.CLIENT_ID,
StringExtensions.URLFormEncode(mRequest.getClientId()),
AuthenticationConstants.OAuth2.REDIRECT_URI,
StringExtensions.URLFormEncode(mRequest.getRedirectUri())
// these are the two lines I've added to make it work
AuthenticationConstants.OAuth2.CLIENT_SECRET,
StringExtensions.URLFormEncode("<MY CLIENT SECRET>")
);
return message;
}
Am I doing something wrong? If not, what is the correct way to access the client secret?
My implementation is straight from the demo application with only changes being setting up the strings to match my endpoints.
Thanks

You need to register your app as a Native application at Azure AD portal. You don't need client secret for native app.

how to determine if a web service is up and running

i was trying to call the following web service from my android app, it hung then completed without returning the result:
web service:http://androidexample.com/media/webservice/JsonReturn.php
However when I clicked on the link, it worked fine - the json file displayed. yet it would not work in my app..
but now, it works fine now in my android app, perhaps it was temporarily down is what I am guessing. How can I know if a web service is up and running for an android app to consume ?

Typically, web services are designed to have a status page that can return status text or a HTTP return code to indicate service status.
If it doesn't have that, you can design a function to periodically do a very basic request with a known result to determine state. This is much better than doing a simple ping.

If it was down it would most likely show a HTML error page, which your app would try to parse, which would cause an error.
I had a similar issue, because I needed to know if the user was returning HTML or the correct JSON, to do this I created the ArrayList I was about to use outside of the try/catch of the parse area. You should do the same if you are using a string.
What I mean is, use:
ArrayList<Something> arrayList = new ArrayList<Something>();
String testString = ""; instead of String testString = null;
I was using only ArrayList<Something> arrayList; at one point which is incorrect. If the user then returns HTML, you won't get an error, the user will simply return an empty arraylist or empty string.
You can then plan for that and show some sort of error message. This way you only need one network request but you can still plan for getting the data back, and the server being down.