如何为 HTTP GET 方法为我的 URL 设置可变端点？

Question

I would like to make the endpoint of the URL in that method a variable one:

public User fetchUser() throws IOException {

        URL url = new URL("https://api.github.com/users/octocat");
        InputStreamReader reader = new InputStreamReader(url.openStream());

        User user = new Gson().fromJson(reader, User.class);
        if (user == null) {
            logger.error("Could not return desired output.");
            return null;
        } else {
            logger.info("The output returned.");
            return user;
        }
    }

Modifying it to this does not solve the case (changed 'octocat' into '{endPoint}'):

public User fetchUser(@PathVariable String endPoint) throws IOException {

        URL url = new URL("https://api.github.com/users/{endPoint}");

This is the GET method from my RestController:

@GetMapping("/user/info/{login}")
    public User getUser(@PathVariable String login) throws IOException {
        return userService.fetchUser();
    }

The browser returns this message:

There was an unexpected error (type=Internal Server Error, status=500).
https://api.github.com/users/{endPoint}

Also, if I modify my URL to this:

URL url = new URL("https://api.github.com/users");

Then the response is this:

There was an unexpected error (type=Internal Server Error, status=500).
java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

Help, please.

Answer 1

For your first exception, you could try using string concatenation to append the endpoint to the URL and see if the connection opens that way:

URL url = new URL("https://api.github.com/users/" + endpoint);

For your second exception, it looks like you're telling GSON you have an object of type User when you actually have an array of some sort. You may have to change the Type parameter in fromJson() so that gson can deserialize the json properly. Here is an example of deserializing arrays in gson.

Since I see you're using spring-web and this looks like a RESTful API, I would also suggest configuring a RestTemplate Bean and injecting it into your service to make the request out to github rather than using java.net.url. You can find a nice guide on spring.io for how that works.