急：connection.connect有问题

手机能上网，Manifest.xml已经申请网络访问。关键代码：//利用Get方法访问网络数据
private void requestDataByGet() {
   try {
       //新建URL对象
       URL url = new URL("http://www.imooc.com/api/shopping?type=11");
       //获取url的连接
       HttpURLConnection connection = (HttpURLConnection) url.openConnection();
       //设置连接属性：超时30s自动不再访问网址
       connection.setConnectTimeout(30 * 1000);
       //设置连接属性：请求访问
       connection.setRequestMethod("GET");
       //设置获取数据格式类型jason
       //设置获取字符集类型UTF-8
       connection.setRequestProperty("Content-Type", "application/jason");
       connection.setRequestProperty("Charset", "UTF-8");
       connection.setRequestProperty("Accept-Charset", "UTF-8");
       connection.connect();//发起连接
       int responseCode = connection.getResponseCode();//获取连接码
       String responseMessage = connection.getResponseMessage();//获取连接信息
       //访问URL成功代码  HttpURLConnection.HTTP_OK=200
       if (responseCode == HttpURLConnection.HTTP_OK)//如果访问成功
       {
           //获取连接的输入流
           InputStream inputStream = connection.getInputStream();
           //把输入流转换成String字符串
           result = streamToString(inputStream);


           //runOnUiThread帮助转到当前操作线程，也就是主线程
           runOnUiThread(new Runnable() {
               @Override
               public void run() {
                   result = decode(result);//把结果转成UTF-8格式

               }
           });
       } else//获取网络数据不成功
       {
           //TODO:error fail
           Log.e(TAG, "run:error code" + responseCode + ",message:" + responseMessage);
       }
   } catch (MalformedURLException e)//捕获异常：不可返的URL地址
   {
       e.printStackTrace();
   } catch (IOException e) {
       e.printStackTrace();
   }
}

运行提示：java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.administrator.gridviewtuangoudemo/com.example.administrator.gridviewtuangoudemo.MainActivity}: android.os.NetworkOnMainThreadException

  at com.example.administrator.gridviewtuangoudemo.MainActivity.requestDataByGet(MainActivity.java:130)

也就是connection.connect连接失败。

断点在connection.setRequestMethod("GET"); 调试数据：this = {MainActivity@830047525032} url = {URL@830048396776} "http://www.imooc.com/api/shopping?type=11" connection = {HttpURLConnectionImpl@830048558736} "com.android.okhttp.internal.http.HttpURLConnectionImpl:http://www.imooc.com/api/shopping?type=11" client = {OkHttpClient@830048400504} selectedProxy = null httpEngine = null httpEngineFailure = null rawRequestHeaders = {RawHeaders@830048559264} redirectionCount = 0 fixedContentLength = -1 responseMessage = null method = "GET" fixedContentLengthLong = -1 instanceFollowRedirects = true HttpURLConnection.fixedContentLength = -1 responseCode = -1 chunkLength = -1 url = {URL@830048396776} "http://www.imooc.com/api/shopping?type=11" defaultHandler = {URLConnection$DefaultContentHandler@830048558872} contentType = null connected = false lastModified = -1 ifModifiedSince = 0 doOutput = false doInput = true connectTimeout = 0 readTimeout = 0 allowUserInteraction = false useCaches = true

断点设connection.connect，调试参数： connection = {HttpURLConnectionImpl@830048579184} "com.android.okhttp.internal.http.HttpURLConnectionImpl:http://www.imooc.com/api/shopping?type=11" this = {MainActivity@830047545480} url = {URL@830048417224} "http://www.imooc.com/api/shopping?type=11" connection = {HttpURLConnectionImpl@830048579184} "com.android.okhttp.internal.http.HttpURLConnectionImpl:http://www.imooc.com/api/shopping?type=11"

断点设int responseCode = connection.getResponseCode();

就出现如上错误提示。

因为有错误，手机调试就是闪屏，出不来东西，无法知道结果。我正在做3-2作业题