Request mapping by method and path in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the HTTP response status when accessing the mapped endpoint?

Consider this Spring Boot controller method:

@RestController
public class MyController {
    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String greet() {
        return "Hello World";
    }
}

What will be the HTTP status code when a client sends a GET request to /hello?

Spring Boot

@RestController
public class MyController {
    @RequestMapping(value = "/hello", method = RequestMethod.GET)
    public String greet() {
        return "Hello World";
    }
}

A 200 OK

B 404 Not Found

C 500 Internal Server Error

D 405 Method Not Allowed

💡 Hint

The method matches the GET request for the path exactly.

The method is mapped to GET requests at path '/hello'. When a GET request is sent to '/hello', the method returns a string and Spring Boot responds with status 200 OK by default.

📝 Syntax

intermediate

Which option correctly maps POST requests to /submit?

You want to create a Spring Boot controller method that handles POST requests to the path /submit. Which of the following method annotations is correct?

A @RequestMapping(path = "/submit", method = RequestMethod.GET)

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

C @RequestMapping(value = "/submit")

D @RequestMapping(method = RequestMethod.POST)

💡 Hint

You need to specify both the path and the POST method explicitly.

Option B correctly specifies the path '/submit' and the HTTP method POST. Option B uses GET instead of POST. Option B does not specify the method, so it defaults to all methods. Option B specifies POST but no path, so it won't map to '/submit'.

🔧 Debug

advanced

Why does this controller method cause a 405 error on POST /data?

Given this controller:

@RestController
public class DataController {
    @RequestMapping(value = "/data", method = RequestMethod.GET)
    public String getData() {
        return "Data";
    }
}

When a client sends a POST request to /data, the server responds with 405 Method Not Allowed. Why?

Spring Boot

@RestController
public class DataController {
    @RequestMapping(value = "/data", method = RequestMethod.GET)
    public String getData() {
        return "Data";
    }
}

A Because the controller is missing @PostMapping annotation

B Because the method throws an exception on POST requests

C Because the path /data is invalid

D Because there is no method mapped to POST requests at /data

💡 Hint

Check which HTTP methods are allowed for the path.

The controller only maps GET requests to /data. POST requests to /data have no matching handler, so Spring Boot returns 405 Method Not Allowed.

🧠 Conceptual

advanced

What happens if two methods map to the same path but different HTTP methods?

In a Spring Boot controller, you have:

@RequestMapping(value = "/item", method = RequestMethod.GET)
public String getItem() { return "Get"; }

@RequestMapping(value = "/item", method = RequestMethod.POST)
public String postItem() { return "Post"; }

What happens when a client sends a GET request and a POST request to /item?

Spring Boot

@RequestMapping(value = "/item", method = RequestMethod.GET)
public String getItem() { return "Get"; }

@RequestMapping(value = "/item", method = RequestMethod.POST)
public String postItem() { return "Post"; }

A GET requests return "Get" and POST requests return "Post"

B Both GET and POST requests return "Get"

C Both GET and POST requests return "Post"

D Requests cause a conflict error at startup

💡 Hint

Spring Boot matches methods by both path and HTTP method.

Spring Boot allows multiple methods mapped to the same path if they differ by HTTP method. GET requests call getItem(), POST requests call postItem().

❓ state_output

expert

What is the response body when sending a PUT request to /update with this controller?

Given this Spring Boot controller:

@RestController
public class UpdateController {
    @RequestMapping(value = "/update", method = {RequestMethod.POST, RequestMethod.PUT})
    public String update() {
        return "Updated";
    }
}

What will be the response body when a client sends a PUT request to /update?

Spring Boot

@RestController
public class UpdateController {
    @RequestMapping(value = "/update", method = {RequestMethod.POST, RequestMethod.PUT})
    public String update() {
        return "Updated";
    }
}

A "Method Not Allowed"

B "Not Found"

C "Updated"

D Empty response body

💡 Hint

The method handles both POST and PUT requests.

The method is mapped to both POST and PUT requests at /update. A PUT request will invoke this method and return "Updated" as the response body.