需要在Android studio上完成开发一个可以实现socket通信的apk，本例实现的Server端和Client端都在同一台设备上实现。
1.添加网络访问权限首先在AndroidManifest.xml文件中添加网络权限。
2.Server端代码编写
Server端中关键性的代码包括：
// socket绑定端口 serverSocket = new ServerSocket(port); // socket等待连接 socket = serverSocket.accept(); // 对接收的信息解码 String msgRecv = dis.readUTF();
注意：socket只能以字节流（Byte）的形式进行传输。
package com.example.socket;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class Server {
ServerSocket serverSocket = null;
public final int port = 9998;
private int i = 0;
public Server(){
//输出服务器的IP地址
try {
InetAddress addr = InetAddress.getLocalHost();
System.out.println("local host:"+addr);
serverSocket = new ServerSocket(port);
System.out.println("0k");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void startService(){
try {
Socket socket = null;
System.out.println("waiting...");
//等待连接，每建立一个连接，就新建一个线程
while(true){
socket = serverSocket.accept();//等待一个客户端的连接，在连接之前，此方法是阻塞的
System.out.println("connect to"+socket.getInetAddress()+":"+socket.getLocalPort());
new ConnectThread(socket).start();
}
} catch (IOException e) {
// TODO Auto-generated catch block
System.out.println("IOException");
e.printStackTrace();
}
}
//向客户端发送信息
class ConnectThread extends Thread{
Socket socket = null;
public ConnectThread(Socket socket){
super();
this.socket = socket;
}
@Override
public void run(){
try {
DataInputStream dis = new DataInputStream(socket.getInputStream());
DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
while(true){
i++;
String msgRecv = dis.readUTF();
System.out.println("msg from client:"+msgRecv);
dos.writeUTF(msgRecv + i);
dos.flush();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
3.Client端代码编写
在Client端的通信使用了Thread以通过多线程实现socket通信的搭建，理论上可以实现多个Client端与Server端的通信传输。
package com.example.socket;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
//IP地址和端口号
public static String IP_ADDRESS = "";
public static int PORT = 9998;
//三个控件
EditText et_message = null; //需要发送的内容
Button bt_getAdress = null; //获取本机IP地址
Button bt_connect = null; //连接并发送
Button bt_startServer = null; //启动服务端
TextView tv_adress = null; //ip地址
TextView tv_reply = null; //服务器回复的消息
//handler
Handler handler = null;
Socket soc = null;
DataOutputStream dos = null;
DataInputStream dis = null;
String messageRecv = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_message = findViewById(R.id.et_message);
bt_getAdress = findViewById(R.id.bt_getAdress);
bt_connect = findViewById(R.id.bt_connect);
bt_startServer = findViewById(R.id.bt_startServer);
tv_adress = findViewById(R.id.tv_adress);
tv_reply = findViewById(R.id.tv_reply);
bt_getAdress.setOnClickListener(v -> {
new Thread(() -> {
try {
InetAddress addr = InetAddress.getLocalHost();
System.out.println("local host:"+addr);
runOnUiThread(() -> tv_adress.setText(addr.toString().split("/")[1]));
} catch (UnknownHostException e) {
e.printStackTrace();
}
}).start();
});
bt_startServer.setOnClickListener(v -> {
new Thread(() -> new Server().startService()).start();
Toast.makeText(MainActivity.this,"服务已启动",Toast.LENGTH_SHORT).show();
});
bt_connect.setOnClickListener(v -> {
IP_ADDRESS = tv_adress.getText().toString();
new ConnectionThread(et_message.getText().toString()).start();
});
handler = new Handler(msg -> {
Bundle b = msg.getData(); //获取消息中的Bundle对象
String str = b.getString("data"); //获取键为data的字符串的值
tv_reply.append(str);
return false;
});
}
//新建一个子线程，实现socket通信
class ConnectionThread extends Thread {
String message = null;
public ConnectionThread(String msg) {
message = msg;
}
@Override
public void run() {
if (soc == null) {
try {
//Log.d("socket","new socket");
if ("".equals(IP_ADDRESS)) {
return;
}
soc = new Socket(IP_ADDRESS, PORT);
//获取socket的输入输出流
dis = new DataInputStream(soc.getInputStream());
dos = new DataOutputStream(soc.getOutputStream());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
dos.writeUTF(message);
dos.flush();
messageRecv = dis.readUTF();//如果没有收到数据，会阻塞
Message msg = new Message();
Bundle b = new Bundle();
b.putString("data", messageRecv);
msg.setData(b);
handler.sendMessage(msg);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
4.xml界面代码编写
主要是实现三个控件以方便进行实验的展示。
实现效果
- 点击获取IP地址可以得到本机的IP地址；点击启动服务实现Server端开启socket服务；在文本框内输入需要传输的文字信息；点击连接发送将信息从Client端发送至Server端，同时Server端会将信息返回并在屏幕上显示。
