How does a router function in Java and what tasks does it solve?

In Java, a router is typically used in the context of web applications to route HTTP requests to the appropriate handlers (controllers). Its task is to determine which code should handle a specific request based on the URL, HTTP method, and other parameters.

For example, in the Spring MVC framework, the router maps URLs to methods annotated with @RequestMapping or @GetMapping.

Main tasks of the router:

• Analyze incoming requests
• Match the path and method with a handler
• Pass request parameters to the handler
• Support RESTful API

An example of simple routing using Spring Boot:

@RestController
public class MyController {

    @GetMapping("/users/{id}")
    public String getUser(@PathVariable String id) {
        return "User ID: " + id;
    }
}

Here, the router directs GET requests to the path /users/{id} to the getUser method.