java - HttpURLConnection POST 请求抛出 IOException

Question

我正在尝试使用 android HttpUrlConnection 发出POST 请求。首先，我使用此处的 GET 请求示例:

http://developer.android.com/training/basics/network-ops/connecting.html#http-client

它工作得很好(例如我得到了 google.com 页面)。然后我做了一些更改来发出 POST 请求:更改 POST 上的请求方法:

conn.setRequestMethod("POST");

并添加此代码(从此处获取:http://developer.android.com/reference/java/net/HttpURLConnection.html):

      conn.setDoOutput(true);
      conn.setChunkedStreamingMode(0);
      OutputStream out = new BufferedOutputStream(conn.getOutputStream());     
      out.close();

现在 downloadUrl 方法如下所示:

private String downloadUrl(String myurl) throws IOException {
  InputStream is = null;
  // Only display the first 500 characters of the retrieved
  // web page content.
  int len = 500;

  try {
      URL url = new URL(myurl);
      HttpURLConnection conn = (HttpURLConnection) url.openConnection();
      conn.setReadTimeout(10000 /* milliseconds */);
      conn.setConnectTimeout(15000 /* milliseconds */);

      conn.setDoInput(true);

      conn.setRequestMethod("POST");
      conn.setDoOutput(true);
      conn.setChunkedStreamingMode(0);
      OutputStream out = new BufferedOutputStream(conn.getOutputStream());     
      out.close();

      // Starts the query
      conn.connect();
      int response = conn.getResponseCode();
      Log.d(DEBUG_TAG, "The response is: " + response);
      is = conn.getInputStream();

      // Convert the InputStream into a string
      String contentAsString = readIt(is, len);
      return contentAsString;

  // Makes sure that the InputStream is closed after the app is
  // finished using it.
  } finally {
      if (is != null) {
          is.close();
      } 
  }
}

并且它总是抛出IOException。你能帮帮我吗，出了什么问题？

Answer 1

这是因为 Android 不允许您在主 UI 线程上启动网络连接。您必须启动一个后台线程(使用 AsyncTask)并从那里执行操作。

更多详细信息in this question .