java post json

To make a POST request with JSON data in Java, you can use the HttpURLConnection class. Here is an example code snippet:

import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.io.OutputStream;

public class JsonPostExample {
  public static void main(String[] args) {
    try {
      // Create the URL and connection objects
      URL url = new URL("http://example.com/api");
      HttpURLConnection conn = (HttpURLConnection) url.openConnection();
      conn.setRequestMethod("POST");
      conn.setRequestProperty("Content-Type", "application/json");
      conn.setRequestProperty("Accept", "application/json");
      conn.setDoOutput(true);

      // Create the JSON data to be sent
      String json = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";

      // Write the JSON data to the connection's output stream
      OutputStream os = conn.getOutputStream();
      os.write(json.getBytes(StandardCharsets.UTF_8));
      os.flush();
      os.close();

      // Check the response code
      int responseCode = conn.getResponseCode();
      System.out.println("Response Code : " + responseCode);

      // Read the response from the connection's input stream
      BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
      String inputLine;
      StringBuffer response = new StringBuffer();
      while ((inputLine = in.readLine()) != null) {
        response.append(inputLine);
      }
      in.close();

      // Print the response
      System.out.println(response.toString());
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

In this example, we create a POST request to send JSON data to an API endpoint. We set the request method to POST and set the Content-Type and Accept headers to application/json. We also set the connection's output stream to write the JSON data to the request body.

After sending the request, we check the response code and read the response from the connection's input stream. We print the response to the console.