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Request Forward to another url in spring boot mvc with mustache template

I am trying to forward the request to another url in spring boot.
I know how to forward the request from one endpoint to another endpoint in the same spring boot application. The code for this is like -
#GetMapping("/home")
public ModelAndView home(#PathVariable(name = "env", required = false) String env) {
return new ModelAndView("index");
}
#GetMapping("/forward")
String callForward(){
return "forward:/home";
}
Here If I go to http://localhost:8080/forward then it will be server by "/home" endpoint and we'll get the home page rendered. Interesting thing here is "url" in the browser remains same http://localhost:8080/forward.
My requirement is > I want to forward to the request to any third party url for example when http://localhost:8080/forward is called I want it to be served by https://google.com/forward.
How can I do it.
I am open to any solution which can fulfill the requirement.

There is a difference between Forward vs Redirect.
Forward: happens on the server-side, servlet container forwards the same request to the target URL, hence client/browser will not notice the difference.
Redirect: In this case, the server responds with 302 along with new URL in location header and then client makes another request to the given URL. Hence, visible in browser
Regarding your concern, it can be achieved using multiple ways.
Using RedirectView
#GetMapping("/redirect")
RedirectView callRedirect(){
return new RedirectView("https://www.google.com/redirect");
}
Using ModelAndView with Prefix
#GetMapping("/redirect")
ModelAndView callRedirectWithPrefix(){
return new ModelAndView("redirect://www.google.com/redirect");
}
Usecase for forwarding could be something like this (i.e. where you want to forward all request from /v1/user to let's /v2/user on the same application)
#GetMapping("/v1/user")
ModelAndView callForward(){
return new ModelAndView("forward:/v2/user");
}
The second approach (using ModelAndView) is preferable as in this case, your controller will have no change where it redirects or forwards or just returning some page.
Note: As mentioned in comments, if you are looking for proxying request, i would suggest checking this SO Thread

Java webapp responding the source code of my login page

I have a java web application which publish a service that returns an object in JSON format, and I have another java web app just to consume that service through a JSONP call and show the response. In my local machine it's working fine, but now that I want to test it in a web environment (Layershift in my case), I can't get the JSON object. I don't see any errors on Chrome developer tools, but when I look into the Response tab (in Network option) I see the source code of the login page of my application. Let me show you the my code
Controller with the service:
#RestController
public class MyController {
#RequestMapping(value="/myservice/get/{somevar}")
public MappingJacksonValue getMyObject (#RequestParam String callback, #PathVariable String somevar, HttpServletRequest request, HttpServletResponse response) {
MyObject obj = new MyObject();
//some logic
MappingJacksonValue value = new MappingJacksonValue(obj);
value.setJsonpFunction(callback);
return value;
}
}
javascript code for call the service:
$.fn.callWithJsonP = function(somevar) {
var url = "/myservice/get/" + somevar + "?callback=myCallback";
$.getJSON(url, function(data) {
if (data.value.status == "OK") {
//shows the data contained
}
});
}
Apache configuration (added to avoid CORS error), present in both applications
Header add Access-Control-Allow-Origin "*"
Header add Access-Control-Allow-Headers "origin, x-requested-with, content-type"
Header add Access-Control-Allow-Methods "PUT, GET, POST, DELETE, OPTIONS"
Header always unset X-Frame-Options
This is working perfectly on muy local machine (except for the Apache, I don't use it locally), but as I said, on a web environment I receive the source code of my login page. In the Headers tab I can see the headers added in Apache, and the status code of the response is OK, any clues about what's goin on?
Kind regards
UPDATEI've removed the Apache web server, and even tested the web service with Postman (meaning, no second application), and still the same result. I've tried changing #RestController for #Controller and returning an instance of MyObject (instead of MappingJacksonValue), with no results, please help me

I am probably way off here, but is it possible that you have a servlet filter or other part of your web app config that is routing your get request to your login page before your REST framework is able to map it to your endpoint? I use Jersey for this usually, so I am unfamiliar with Spring's RestController, but I assume it is doing similar thing - routes URLs that match to the java code. If you are seeing login page in response it sounds like something is interfering and trying to force user to login before Spring directs to your endpoint method.

It seems like you have a fallback set in your server, maybe configured for a single page application. This is normally used for routing with HTML5 mode using routers like angular's.

you are getting the login page code as response because the login is failed and you are redirected to the same page.. so before calling the service first you need to do the authentication and then by using the authentication token call the service..

Is it the only way of URL mapping to select a controller to run?

The first step, in SpringMVC application, may be mapping a URL to one Controller (not a Jsp page) to display the HomePage using GET method, isn't it? After the form, in my spicific app, is filled, the same controller get the information, do some verifications and the return a logical view name to InternalViewResolver to show the second page.
My question is: when user click a icon or button in the second page, how does the next controller be selected to run? Is still a URL mapping? or any way else?
thanks!
kenneth

Short answer is, Yes. Whether you use ajax request or form submission, you will need to have a controller with appropriate mapping url that will process your request further depending on the code your controller contains.

when user click a icon or button in the second page, how does the next controller be selected to run? Is still a URL mapping? or any way else?
yes, because Spring MVC uses url pattern which itself is a concise and simple way for mapping set of urls.
When you click image or link in ur view page, you allow Controller and DispatcherServlet to receive user's request and after that dispatch request to controller. Then MappingHandler will choose which one is right url request that client requesting by following HttpServletRequest mechanism.
public interface HandlerMapping {
HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception;
}
After this Controller will do real work of processing request/view page.
Note that: URL pattern itself follow simple ways to run the correct url by analyzing every character in a pattern which must match the corresponding character in the URL path exactly with two exceptions.
In Spring MVC, you can do either this
Other site
or that
<spring:url value="/othersite"/>
then URL pattern will be matched by controller itself.

How to redirect a HTTPRequest from one controller class to other controller class?

I have two controller. One is main controller and other is intermediate controller. In intermediate controller I should add header to HTTPRequest. After Adding I should redirect it to main controller where I should check the header I added. How can I do this? Can anyone help me for this?pls........

Seems like a good place to use Servlet Filter . If you want to pre-process an incoming request you could do this with servlet filters and then simply chain it to the appropriate servlet .
Refer BalusC Answer for details .
If this is not the case your can merely forward the request like :
request.getRequestDispatcher("/yourServlet").forward(request, response); // forward to the main servlet

Forward Dispatching
getServletContext().getRequestDispatcher().forward("second page");
The request forwarding is done internally by the JSF Controller Servlet to another resource. The browser is unaware of what has happened in the server side at the web container. So it still thinks it is tending to the original request and displays the original URL in its address bar. However, the page content displayed is from the second page.
Redirect Dispatching
response.sendRedirect("second page");
In this case, the JSF Controller Servlet instructs the client browser (via HTTP response header) to fetch another URL. So the browser fetches entirely a new URL and displays the second URL in its address bar. This could cause slight performance delay
from here

I think you need to forward the request rather than redirecting.
RequestDispatcher dispatcher= request.getRequestDispatcher("servlet-mapped-url");
dispatcher.forward(request, response);

How to redirect all new user requests to front page in Spring MVC?

I want to secure (temporarily) my application by create front page with captcha and simple form. I suppose Spring Security is too complicated for this task. How can I catch all requests and check if some attribute in session is set? If it is set then all these #RequestMapping methods should be executed, otherwise redirect to one front page.

Have a handler interceptor defined and applied to all the handlers. The example in that link shows you also how to perform the redirect. Also check the mvc:interceptors for the Spring 3 - like configuration.

You can simply configure a Filter for this