Android平台有三种网络接口可以使用，他们分别是：java.net.*(标准Java接口)、Org.apache接口和Android.net.*(Android网络接口)。下面分别介绍这些接口的功能和作用。
1.标准Java接口
java.net.*提供与联网有关的类，包括流、数据包套接字(socket)、Internet协议、常见Http处理等。比如：创建URL，以及URLConnection/HttpURLConnection对象、设置链接参数、链接到服务器、向服务器写数据、从服务器读取数据等通信。这些在Java网络编程中均有涉及，我们看一个简单的socket编程，实现服务器回发客户端信息。
服务端：
public class Server implements Runnable{
@Override
public void run() {
Socket socket = null;
try {
ServerSocket server = new ServerSocket(18888);
//循环监听客户端链接请求
while(true){
System.out.println("start...");
//接收请求
socket = server.accept();
System.out.println("accept...");
//接收客户端消息
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String message = in.readLine();
//发送消息，向客户端
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);
out.println("Server:" + message);
//关闭流
in.close();
out.close();
}
} catch (IOException e) {
e.printStackTrace();
}finally{
if (null != socket){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
//启动服务器
public static void main(String[] args){
Thread server = new Thread(new Server());
server.start();
}
}
客户端，MainActivity
public class MainActivity extends Activity {
private EditText editText;
private Button button;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
editText = (EditText)findViewById(R.id.editText1);
button = (Button)findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Socket socket = null;
String message = editText.getText().toString()+ "\r\n" ;
try {
//创建客户端socket,注意:不能用localhost或127.0.0.1，Android模拟器把自己作为localhost
socket = new Socket("<span style="font-weight: bold;">10.0.2.2</span>",18888);
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter
(socket.getOutputStream())),true);
//发送数据
out.println(message);
//接收数据
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String msg = in.readLine();
if (null != msg){
editText.setText(msg);
System.out.println(msg);
}
else{
editText.setText("data error");
}
out.close();
in.close();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
finally{
try {
if (null != socket){
socket.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
});
}
}