Question

我在Android世界中很新，我正在开发一个应用程序，但我无法建立任何互联网连接（或者即使我尝试发送电子邮件）连接和wifi。一切正常，直到（例如）：

之类的命令

HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setReadTimeout(10000);

conn.setConnectTimeout(15000);

conn.setRequestMethod("GET");

conn.setDoInput(true);

conn.connect();    // here it fails

OR

InetAddress indirizzo = InetAddress.getByName("www.websitename.com"); // here it fails

OR

FTPClient ftpClient = new FTPClient();

ftpClient.connect("xxx.xxx.xxx.xxx",21);  // here it fails

我已经尝试了很多我在不同教程中找到的解决方案：代码在我的PC上在java应用程序中正常工作，但相同的代码在我的智能手机和AVD上都不起作用。我已经在清单文件中使用了所有必需的权限：

"android.permission.INTERNET"

"android.permission.ACCESS_NETWORK_STATE"

但我认为缺少某些东西。有人能帮帮我吗？谢谢！

Answer 1

首先检查您的设备是否有互联网连接： -

public static boolean CheckInternet(Context context) 
{
    ConnectivityManager connec = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    android.net.NetworkInfo wifi = connec.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
    android.net.NetworkInfo mobile = connec.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

    return wifi.isConnected() || mobile.isConnected();
}

阅读以下文档： -

http://developer.android.com/reference/java/net/HttpURLConnection.html

http://developer.android.com/reference/java/net/URLConnection.html

private void downloadImage(String urlStr) {
        progressDialog = ProgressDialog.show(this, "", "Fetching Image...");
        final String url = urlStr;

        new Thread() {
            public void run() {
                InputStream in = null;
                Message msg = Message.obtain();
                msg.what = 1;
                try {
                    in = openHttpConnection(url);
                    bitmap = BitmapFactory.decodeStream(in);
                    Bundle b = new Bundle();
                    b.putParcelable("bitmap", bitmap);
                    msg.setData(b);
                    in.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
                messageHandler.sendMessage(msg);    

            }
        }.start();

    }

Internet连接失败

1 个答案: