写一个java方法，访问公网ip端口传递json

以下是一个示例Java方法，使用HttpURLConnection类发送JSON数据到公共IP地址和端口：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class JsonSender {
	
	public static void sendJson(String ip, int port, String json) throws IOException {
		String url = "http://" + ip + ":" + port;
		URL obj = new URL(url);
		HttpURLConnection con = (HttpURLConnection) obj.openConnection();
		
		// 设置请求方法为POST
		con.setRequestMethod("POST");
		
		// 设置请求头
		con.setRequestProperty("Content-Type", "application/json");
		
		// 启用输出流
		con.setDoOutput(true);
		
		// 获取输出流并写入JSON数据
		OutputStream os = con.getOutputStream();
		os.write(json.getBytes("UTF-8"));
		os.flush();
		os.close();
		
		// 获取响应结果
		int responseCode = con.getResponseCode();
		System.out.println("Response Code: " + responseCode);
		
		// 读取响应结果
		BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
		String inputLine;
		StringBuffer response = new StringBuffer();
		while ((inputLine = in.readLine()) != null) {
			response.append(inputLine);
		}
		in.close();
		
		// 输出响应结果
		System.out.println("Response Body: " + response.toString());
	}
	
	public static void main(String[] args) throws IOException {
		String ip = "your.public.ip.address";
		int port = 8080;
		String json = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";
		sendJson(ip, port, json);
	}

}

在使用该方法时，需要将`your.public.ip.address`替换为实际的公共IP地址，`8080`替换为实际的端口号，以及`{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}`替换为实际的JSON数据。