如何使用套接字从服务器的主机名中了解IP

Question

我正在使用sokets制作android应用程序，客户端将消息发送到服务器。 此时，客户端从我放入editText中的数据（ip和端口号）发送一条消息。 是否有可能无需手动即可知道服务器的ip，例如，如果客户端知道服务器的名称将使用DNS知道您的ip ...因此，客户端可以向服务器发送消息而不必搜索ip自动。 谁能帮我？

这是来自客户端的代码：

        public class MainActivity extends Activity {
            TextView textResponse;
            EditText editTextAddress, editTextPort;
            Button buttonConnect, buttonClear;
            EditText welcomeMsg;

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);

                editTextAddress = (EditText) findViewById(R.id.address);
                editTextPort = (EditText) findViewById(R.id.port);
                buttonConnect = (Button) findViewById(R.id.connect);
                buttonClear = (Button) findViewById(R.id.clear);
                textResponse = (TextView) findViewById(R.id.response);
                welcomeMsg = (EditText)findViewById(R.id.welcomemsg);
                buttonConnect.setOnClickListener(buttonConnectOnClickListener);

                buttonClear.setOnClickListener(new View.OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        textResponse.setText("");
                    }
                });
            }

            View.OnClickListener buttonConnectOnClickListener = new View.OnClickListener() {

                @Override
                public void onClick(View arg0) {

                    String tMsg = welcomeMsg.getText().toString();
                    if(tMsg.equals("")){
                        tMsg = null;
                        Toast.makeText(MainActivity.this, "No Welcome Msg sent", Toast.LENGTH_SHORT).show();
                    }
        //Search ip and editText port number
                    MyClientTask myClientTask = new MyClientTask(editTextAddress.getText().toString(), Integer.parseInt(editTextPort.getText().toString()),
                            tMsg);
                    myClientTask.execute();
                }
            };

            public class MyClientTask extends AsyncTask<Void, Void, Void> {

                String dstAddress;
                int dstPort;
                String response = "";
                String msgToServer;

                MyClientTask(String addr, int port, String msgTo) {
                    dstAddress = addr;
                    dstPort = port;
                    msgToServer = msgTo;
                }

                @Override
                protected Void doInBackground(Void... arg0) {

                    Socket socket = null;
                    DataOutputStream dataOutputStream = null;
                    DataInputStream dataInputStream = null;

                    try {
        //create the conection  between the client and the server using the ip and port number
                        socket = new Socket(dstAddress, dstPort);
                        dataOutputStream = new DataOutputStream(
                                socket.getOutputStream());
                        dataInputStream = new DataInputStream(socket.getInputStream());

    //send message to the server
                        if(msgToServer != null){
                            dataOutputStream.writeUTF(msgToServer);
                        }

                        response = dataInputStream.readUTF();

                    } catch (UnknownHostException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                        response = "UnknownHostException: " + e.toString();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                        response = "IOException: " + e.toString();
                    } finally {
                        if (socket != null) {
                            try {
//close the conection
                                socket.close();
                            } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }
                        }

                        if (dataOutputStream != null) {
                            try {
                                dataOutputStream.close();
                            } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }
                        }

                        if (dataInputStream != null) {
                            try {
                                dataInputStream.close();
                            } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }
                        }
                    }
                    return null;
                }

                @Override
                protected void onPostExecute(Void result) {
                    textResponse.setText(response);
                    super.onPostExecute(result);
                }
            }
        }


        Layout: 
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            tools:context=".MainActivity" >

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_horizontal"
                android:autoLink="web"
                android:text="http://android-er.blogspot.com/"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/info"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />
            <TextView
                android:id="@+id/infoip"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />

            <ScrollView
                android:layout_width="match_parent"
                android:layout_height="match_parent" >

                <TextView
                    android:id="@+id/msg"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content" />
            </ScrollView>

        </LinearLayout>

Answer 1

代替

socket = new Socket(dstAddress, dstPort);

采用：

socket = new Socket();
SocketAddress sockaddr = new InetSocketAddress(dstAddress, dstPort);
socket.connect(sockaddr, CONNECT_TIMEOUT_MILLISECONDS);

它将接受数字IP或主机名