Spring Boot REST Template URI Encoding

Hard coding a URI endpoint for the Rest template interface is preferably the first point of reference when implementing a micro service or a monolith application.

There is no easy way to do this!

URI variables are usually meant for path elements, query string parameters, or when you decouple your application from your front-end. Ideally, you'd find a better solution for constructing your URI to access data on various endpoints. But, after doing a couple of endpoint hits, you'll probably run into a funny looking error like

org.springframework.web.client.ResourceAccessException: I/O error: http://localhost:8080%api%users

 Regardless of all the research, the URI  package comes in quite handy with String Builder to Query a API. There are a few ways of implementing this:

StringBuilder builder = new StringBuilder("http://localhost:8080/api/users");

URI uri = URI.create(builder.toString());

List<Users> updatedUsers = restTemplate.getForObject(uri, List.class);

This returns a list of users on a GET request in the Rest Template. If you're using the POST request, append your parameters in a string builder like in the snippet below:

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StringBuilder builder = new StringBuilder("http://localhost:8080/api/adduser");

        builder.append("?username=");

builder.append(URLEncoder.encode("john@1.com",StandardCharsets.UTF_8.toString()));

        builder.append("&password=");

        builder.append(URLEncoder.encode("P@$$word",StandardCharsets.UTF_8.toString()));

        builder.append("&phone=");

        builder.append(URLEncoder.encode("911",StandardCharsets.UTF_8.toString()));

    URI uri = URI.create(urlencoded);

restTemplate.postForObject(uri, Users.class);

If using special characters, you might want to use the URL encoder on specific charsets. In this case, we're using UTF_8. This is a huge question mark around just submitting a hard coded URL or how the Rest template behaves.

OR the easiest way is to simply just submit an object on a hard coded URI for your POST Query. 

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@RequestMapping(value = "/addNewUser", method = RequestMethod.POST)

    public ModelAndView processRequest(HttpServletRequest request, HttpSession session, @RequestParam("username")String username, @RequestParam("password")String password, @RequestParam("phone")String phone) {

        RestTemplate restTemplate = new RestTemplate();

        Users user = new Users();

        user.setUsername(username);

        user.setPassword(password);

        user.setPhone(phone);

        user.setEnabled(true);

        restTemplate.postForObject("http://localhost:8080/api/adduser", user, Users.class);

        StringBuilder builder = new StringBuilder("http://localhost:8080/api/users");

        URI uri = URI.create(builder.toString());

        List<Users> updatedUsers = restTemplate.getForObject(uri, List.class);

        session = request.getSession(false);

        ModelAndView model = new ModelAndView();

        if(session != null){

            model.setViewName("welcome");

            model.addObject("users", updatedUsers);

            model.addObject("user", (Users)session.getAttribute("user"));

            model.addObject("sessiontracker", sessiontracker.getList());

            model.addObject("sumValidSessions", sessiontracker.getSizeSessionList());

            return model;

        }

        return new ModelAndView("login");

    }

The GUI sample i'm using adds a user and displays it in a user table.

So, it all depends on which version of Spring you're using. If you're using an old version of Spring, the UriComponentsBuilder with your spring-web jar wont be included. For more information on standard URI 's and encoding click on this link: Java URL Encoding.

Delving into URI 's can get quite complex with Rest Template. Nevertheless, I'll recommend this for a monolithic application or If you want a quick metrics GUI around your microservices data. Don't disregard that Spring allows you to develop two Controller types, a standard MVC Controller, and a Rest Controller, which gives you the capabilities of exposing an API. 

It is favorable nonetheless to use an HTTP client for B2B communications on URLs in a microservice environment, which adds much more customization around exceptions and Response codes. 

I hope this helps to find traction on the route to take and I hope this gives you some variance around Spring Boot Rest API.

Thank you!