Java REST API HttpClient példa

• Szerző: Sallai András
• Copyright © 2023, Sallai András
• Licenc: CC BY-SA 4.0
• Web: https://szit.hu

Client.java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CompletableFuture;
 
public class Client {
    public CompletableFuture<String> get(String urlStr) {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest req = HttpRequest.newBuilder()
        .uri(URI.create(urlStr))        
        .build();
 
        return client.sendAsync(req, BodyHandlers.ofString())
        .thenApply(HttpResponse::body);
    }
    public CompletableFuture<String> post(String url, String body, String... token) {
 
        HttpClient client = HttpClient.newHttpClient();
 
        HttpRequest req = HttpRequest.newBuilder()
        .uri(URI.create(url))
        .header("Content-Type", "application/json")
        .header("Authorization", "Bearer " + token[0])
        .POST(HttpRequest.BodyPublishers.ofString(body))
        .build();
 
        return client.sendAsync(req, BodyHandlers.ofString())
        .thenApply(HttpResponse::body);        
    }
    public CompletableFuture<String> put(String url, String body) {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest req = HttpRequest.newBuilder()
        .uri(URI.create(url))
        .header("Content-Type", "application/json")
        .PUT(HttpRequest.BodyPublishers.ofString(body))
        .build();
 
        return client.sendAsync(req, BodyHandlers.ofString())
        .thenApply(HttpResponse::body);        
    }
    public CompletableFuture<String> delete(String url) {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest req = HttpRequest.newBuilder()
        .uri(URI.create(url))
        .header("Content-Type", "application/json")
        .DELETE()
        .build();
 
        return client.sendAsync(req, BodyHandlers.ofString())
        .thenApply(HttpResponse::body);        
    }
 
}

Emp.java

public class Emp {
    Client client;
    String host;
    String endpoint;
    public Emp() {
        this.client = new Client();
        this.host = "http://[::1]:8000/api";
        this.endpoint =  "/employees";
    }
    public String getEmployees() {
        String url = host + endpoint;
        String res = client.get(url).join();
        return res;
    }
    public String addEmployee(String emp) {
        String token = "eyJhbGci";
        Client client = new Client();
        String url = host + endpoint;
        String res = client.post(url, emp, token ).join();
        return res;
    }
    public String updateEmployee(String emp, Integer id) {
        String url = this.host + endpoint + "/" + id.toString();
        String res = client.put(url, emp ).join();
        return res;
    }
    public String deleteEmployee(Integer id) {
        String url = host + endpoint + "/" + id.toString();
        String res = client.delete(url).join();
        return res;
    }
 
}

Man.java

public class Man {
    Emp emp;
    public Man() {
        this.emp = new Emp();
 
        create();
        // index();
        // login();
    }
    public void index() {
        String res = this.emp.getEmployees();
        System.out.println(res);
    }
    public void create() {        
        String pali1 = "{ \"name\":\"Teknős Péter\",";
        String pali2 = "\"city\":\"Hatvan\",";
        String pali3 = "\"salary\": 322 }";
        String data = pali1 + pali2 + pali3;
        String res = this.emp.addEmployee(data);
        System.out.println(res);
    }
    public void update() {
        String pali1 = "{ \"name\":\"Csengő Mária\",";
        String pali2 = "\"city\":\"Pécs\",";
        String pali3 = "\"salary\": 349 }";
        String data = pali1 + pali2 + pali3;
        String res = this.emp.updateEmployee(data, 4);
        System.out.println(res);
    }
    public void delete() {
        String res = this.emp.deleteEmployee(6);
        System.out.println(res);
    }
    public void login() {
        Auth auth = new Auth();
        String data1 = "{ \"name\":\"mari\",";
        String data2 = "\"password\":\"titok\"}";        
        String data = data1 + data2;
        String res = auth.login(data);
        System.out.println(res);
    }
}

Auth.java

public class Auth {
    Client client;
    String host;
    String endpoint;
    public Auth() {
        this.client = new Client();
        this.host = "http://[::1]:8000/api";
        this.endpoint =  "/login";
    }    
    public String login(String data) {
        Client client = new Client();
        String url = host + endpoint;
        String res = client.post(url, data ).join();
        return res;
    }    
}

App.java

public class App {
    public static void main(String[] args) throws Exception {
        new Man();
    }
}

A fejrészt csak akkor adjuk hozzá, ha át van adva a token, ami nem kötelező.

    public CompletableFuture<String> post(String url, String body, String... token) {
 
        HttpClient client = HttpClient.newHttpClient();
 
        List<String> headers = new ArrayList<>();
        headers.add("Content-Type");
        headers.add("application/json");
        System.out.println(token.length);
        if(token.length > 0) {
            headers.add("Authorization");
            headers.add("Bearer " + token[0]);
        }
        HttpRequest req = HttpRequest.newBuilder()
        .uri(URI.create(url))
        .headers(headers.toArray(String[]::new))
        .POST(HttpRequest.BodyPublishers.ofString(body))
        .build();
 
        return client.sendAsync(req, BodyHandlers.ofString())
        .thenApply(HttpResponse::body);        
    }