通过java.netHttpURLConnection类实现java发送http请求

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

public static String postForBody(String param) {
try {
URL url = new URL(“https://usapp-open.ulifecam.com”);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        // 设置请求方法为POST
        connection.setRequestMethod("POST");

        // 设置请求头，指示内容类型为JSON
        connection.setRequestProperty("Content-Type", "application/json");

        // 设置请求体
        byte[] outputInBytes = param.getBytes("UTF-8");
        int outputLength = outputInBytes.length;

        // 设置内容长度
        connection.setRequestProperty("Content-Length", String.valueOf(outputLength));

        // 默认情况下，该URLConnection的DoOutput属性为false。
        // 我们需要设置DoOutput为true，表明我们要输出数据。
        connection.setDoOutput(true);

        // 发送请求体
        try (OutputStream os = connection.getOutputStream()) {
            os.write(outputInBytes, 0, outputLength);
        }

        // 获取响应码
        int responseCode = connection.getResponseCode();

        // 根据需要获取响应内容
        if (responseCode == HttpURLConnection.HTTP_OK) { // 200
            try (java.io.BufferedReader in = new java.io.BufferedReader(new java.io.InputStreamReader(connection.getInputStream()))) {
                String inputLine;
                StringBuilder response = new StringBuilder();
                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                System.out.println("Response Body: " + response.toString());
                return response.toString();
            }
        }

        // 关闭连接
        connection.disconnect();
        return null;

    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}