有没有办法使用 JAVA 中具有长参数的 POST 请求？

Question

我需要使用需要多个参数的 POST 方法进行请求，其中一个是长字符串。 这个长字符串参数大约是 250kb，它是 xml 字符串，如

"<ROOT><table><a></a><b>b</b><c>c</c></table><table>...</table><table>...</table></ROOT>"

我试过 HttpURLConnection

try{
    URL url = new URL(myUrl);
    HttpURLConnection http = (HttpURLConnection) url.openConnection();
    http.setDefaultUseCaches(false);
    http.setDoInput(true);
    http.setDoOutput(true);
    http.setRequestMethod("POST");
    //http.setRequestProperty("content-type", "application/x-www-form-urlencoded");
    http.setRequestProperty("Authorization", header);
            
    StringBuffer buffer = new StringBuffer();
    if(map != null){
        Set key = map.keySet();
                
        for(Iterator iterator = key.iterator(); iterator.hasNext();){
            String keyName = (String) iterator.next();
            String valueName = (String) map.get(keyName);
            buffer.append(keyName).append("=").append(valueName);
        }
    }
    OutputStreamWriter outStream = new OutputStreamWriter(http.getOutputStream(), "UTF-8");
    PrintWriter writer = new PrintWriter(outStream);
    System.out.println("buffer.toString() : " + buffer.toString());
    writer.write(buffer.toString());
    writer.flush();
            
    InputStreamReader tmp = new InputStreamReader(http.getInputStream(), "UTF-8");
    BufferedReader reader = new BufferedReader(tmp);
    StringBuilder builder = new StringBuilder();
    String str;
    while((str = reader.readLine()) != null){
        builder.append(str + "\n");
    }
    myResult = builder.toString();
    return myResult;
}catch(Exception e){
    e.printStackTrace();
}

当我检查 buffer.toString 时，参数之间没有“&”，我认为这可能是一个问题。 所以我尝试过像“buffer.append("&" + keyName)”，但它的返回显示“没有为参数号 1 设置值。”