Java实现发起HTTP请求的四种方法实现与适用场景

public class HttpUrlConnectionExample {
    public static void main(String[] args) throws Exception {
        URL url = new URL("https://api.example.com/data");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        
        int responseCode = conn.getResponseCode();
        BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();
        
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
        System.out.println(response.toString());
    }
}

public class ApacheHttpClientExample {
    public static void main(String[] args) throws Exception {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet request = new HttpGet("https://api.example.com/data");
        
        try (CloseableHttpResponse response = httpClient.execute(request)) {
            String result = EntityUtils.toString(response.getEntity());
            System.out.println(result);
        }
    }
}

public class OkHttpExample {
    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
            .url("https://api.example.com/data")
            .build();
        
        try (Response response = client.newCall(request).execute()) {
            System.out.println(response.body().string());
        }
    }
}

public class Java11HttpClientExample {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://api.example.com/data"))
            .build();
        
        HttpResponse<String> response = client.send(
            request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.body());
    }
}

public class OkHttpPostExample {
    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        MediaType JSON = MediaType.get("application/json; charset=utf-8");
        String jsonBody = "{\"name\":\"John\", \"age\":30}";
        
        Request request = new Request.Builder()
            .url("https://api.example.com/post")
            .post(RequestBody.create(jsonBody, JSON))
            .build();
        
        try (Response response = client.newCall(request).execute()) {
            System.out.println(response.body().string());
        }
    }
}