我've been looking at this for a while now. I' m尝试使用chat.postMessage（https://slack.com/api/chat.postMessage）的网址向松弛 Channels 发布消息和一些按钮 . 这是存储在messagePostURL变量中的url . 我的PostingConstants.relevancePost变量保存了在https://api.slack.com/docs/message-buttons找到的交互式消息的松弛按钮教程上显示的确切JSON，并且我已将我的 Channels 名称和令牌添加到JSON代码中 . 发送到webhook时，相同的JSON代码可以正常工作，但不能直接将其发送到chat.postMessage网址 . 为什么这不能正常工作？

String urlParameters  = PostingConstants.relevancePost;
    byte[] postData       = urlParameters.getBytes( StandardCharsets.UTF_8 );
    int    postDataLength = postData.length;
    //String request        = messagePostURL;
    URL    url            = new URL( messagePostURL );
    HttpURLConnection conn= (HttpURLConnection) url.openConnection();
    conn.setDoOutput( true );
    conn.setInstanceFollowRedirects( false );
    conn.setRequestMethod( "POST" );
    conn.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded");
    conn.setRequestProperty( "charset", "utf-8");
    conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
    conn.setUseCaches( false );
    try( DataOutputStream wr = new DataOutputStream( conn.getOutputStream())) {
        wr.write( postData );
    }

打印conn.getResponseCode（）给出200（这对我来说很好），打印conn.getResponseMessage（）给出OK（再次应该是好的） .

java http-post slack-api