JAVA URLConnection.getInputStream为NULL 该怎么解决？

Question

在做接口对接到时候 本地电脑测试代码正常执行，但到了另外电脑 代码执行过程虽然不报错 但是conn.getInputStream始终为NULL，把接口地址url直接复制到浏览器地址上是可以的 比较急哪位大神告诉下解决方法 百度了很多都没用

public static String post(String url, String data, String D_METHOD) {
    PrintWriter out = null;
    BufferedReader in = null;
    String result = "";
    try {
        URL realUrl = new URL(url);
        // 打开和URL之间的连接
        URLConnection conn = realUrl.openConnection();
        // 设置通用的请求属性
        conn.setRequestProperty("Content-Type", "Application/json;charset=utf-8");
        conn.setRequestProperty("accept", "application/json");
         conn.setRequestProperty("User-Agent","Mozilla/5.0 (Windows NT 6.1; WOW64)");
        conn.setRequestProperty("sun.net.http.retryPost", "false");
        // 发送POST请求必须设置如下两行
        conn.setDoOutput(true);
        conn.setDoInput(true);
        // 获取URLConnection对象对应的输出流
        OutputStreamWriter pu = new OutputStreamWriter(conn.getOutputStream(), "utf-8");
        out = new PrintWriter(pu);
        // 发送请求参数
        out.print(data);
        // flush输出流的缓冲
        out.flush();
        // 定义BufferedReader输入流来读取URL的响应
        in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "utf-8"));

        String line;
        while ((line = in.readLine()) != null) {
            result += line;
        }
    } catch (Exception e) {
    System.out.println("发送请求异常");
        e.printStackTrace();
    } finally {
        try {
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
    return result;
}

Answer 1

https://blog.csdn.net/qq_41032995/article/details/87864387