What are HTTP methods?

HTTP methods (verbs or commands) define actions that can be performed on the resource specified in the request URI.

Main methods:

• GET: Requests a representation of the specified resource. Request data is sent in the URL. Used to retrieve data.
• POST: Sends data to be processed to the specified resource. Request data is sent in the body. Used to create or update a resource.
• PUT: Replaces all current representations of the resource with the content of the request body. Used to update a resource.
• DELETE: Deletes the specified resource. Used to delete a resource.
• PATCH: Applies partial modifications to the resource.
• HEAD: Requests the same headers as GET, but without the response body.
• OPTIONS: Describes the HTTP methods supported by the server for the specified URL.

Properties of methods:

• Idempotency: Performing the same request multiple times results in the same resource state as performing it once. Idempotent methods: GET, PUT, DELETE, HEAD, OPTIONS. Non-idempotent: POST, PATCH.
• Safety: The request does not change the state of the resource on the server. Safe methods: GET, HEAD, OPTIONS. Unsafe methods: POST, PUT, DELETE, PATCH.

// Example of a GET request in Java using HttpClient
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
        .uri(URI.create("https://api.example.com/resource"))
        .GET()  // Method
        .build();
HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println(response.body());

// Example of a POST request in Java
String postBody = "{\"name\":\"test\", \"value\":\"data\"}";
HttpRequest postRequest = HttpRequest.newBuilder()
        .uri(URI.create("https://api.example.com/resource"))
        .POST(HttpRequest.BodyPublishers.ofString(postBody)) // Method
        .header("Content-Type", "application/json")
        .build();
HttpResponse<String> postResponse = client.send(postRequest, HttpResponse.BodyHandlers.ofString());
System.out.println(postResponse.body());