【达内课程】利用Socket实现群聊

思路

服务端实现

客户端实现

注意

按照以上思路完成服务端
ChatServer

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class ChatServer {
    private List<Socket> sockets = new ArrayList<Socket>();
    /**
     * 开启服务
     * @throws IOException 
     */
    public void startServer() throws IOException{
        System.out.println("服务已启动...");
        //启动服务
        ServerSocket ss = new ServerSocket(8888);
        //不断接收从客户端发来的消息
        while(true){
            //阻塞执行，接收客户端连接
            Socket socket = ss.accept();
            sockets.add(socket);
            //想要并发处理的话，需要开启线程
            new WorkThread(socket).start();
        }
    }

     /**
     * 工作线程
     * 接收客户端的消息，并给每个线程发一遍
     */
    class WorkThread extends Thread{
        private Socket socket;
        public WorkThread(Socket socket){
            this.socket = socket;
        }
        public void run(){
            try {
                DataInputStream dis = new DataInputStream(socket.getInputStream());
                while (true){
                    String message = dis.readUTF();
                    //给每一个客户端都发一遍
                    for(int i=0;i<sockets.size();i++){
                        Socket s = sockets.get(i);
                        DataOutputStream dos = new DataOutputStream(s.getOutputStream());
                        dos.writeUTF(message);
                        dos.flush();
                    }
                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                //当开启一条线程后，线程会等待客户端发消息
                //在等待的过程中，可能出现异常，比如连接中断，就会抛出connection reset的异常
                //就会走到这里

                System.out.println("连接中断");
                //把当前socket对象从集合中移除
                sockets.remove(socket);
            }
        }
    }

    public static void main(String[] args){
        ChatServer server = new ChatServer();
        try {
            server.startServer();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

布局文件
activity_main

<RelativeLayout 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="com.example.xx.myapplication.MainActivity">

    <EditText
        android:id="@+id/et_ip"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_toLeftOf="@+id/btn_ip" />

    <Button
        android:id="@+id/btn_ip"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:text="确定" />

    <ListView
        android:id="@+id/listview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/btn_message"
        android:layout_below="@+id/btn_ip" />

    <Button
        android:id="@+id/btn_message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:text="确定" />

    <EditText
        android:id="@+id/et_message"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_toLeftOf="@+id/btn_message" />
</RelativeLayout>

MainActivity

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private EditText et_ip;
    private EditText et_message;
    private Button btn_ip;
    private Button btn_message;
    private ListView listview;
    private Socket socket;

    private DataInputStream dis;
    private DataOutputStream dos;

    private List<String> messages = new ArrayList<>();
    private ArrayAdapter<String> adapter;

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case HANDLER_CONNECT_SUCCESS://连接成功
                    Toast.makeText(MainActivity.this, "连接成功", Toast.LENGTH_SHORT).show();
                    et_ip.setEnabled(false);
                    btn_ip.setEnabled(false);
                    break;
                case HANDLER_MESSAGE_RECEIVED://接受到消息
                    String message = (String)msg.obj;
                    messages.add("小明："+message);
                    //更新adapter
                    adapter.notifyDataSetChanged();
                    //显示最后一条
                    listview.setSelection(messages.size()-1);
                    break;
            }
        }
    };

    private static final int HANDLER_CONNECT_SUCCESS = 1;
    private static final int HANDLER_MESSAGE_RECEIVED = 2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setViews();
        //设置适配器
        setAdapter();
    }

    private void setAdapter() {
        adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,messages);
        listview.setAdapter(adapter);
    }

    private void setViews() {
        et_ip = findViewById(R.id.et_ip);
        et_message = findViewById(R.id.et_message);
        btn_ip = findViewById(R.id.btn_ip);
        btn_message = findViewById(R.id.btn_message);
        listview = findViewById(R.id.listview);

        btn_ip.setOnClickListener(this);
        btn_message.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_ip:
                //建立连接
                new Thread() {
                    @Override
                    public void run() {
                        try {
                            connect();
                        } catch (IOException e) {
                            e.printStackTrace();
                            //连接建立失败
                        }
                    }
                }.start();
                break;
            case R.id.btn_message:
                //发送消息
                new Thread() {
                    @Override
                    public void run() {
                        try {
                            sendMessage();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }.start();
                break;
        }
    }

    private void sendMessage() throws IOException {
        String text = et_message.getText().toString();
        dos.writeUTF(text);
        dos.flush();
    }

    /**
     * 读取服务端发回的消息的工作线程
     */
    class ReadThread extends Thread {
        //run方法执行完毕后，线程也就销毁了
        //垃圾回收机制会回收
        @Override
        public void run() {
            /*while (true){
                try {
                    String message = dis.readUTF();
                } catch (IOException e) {
                    e.printStackTrace();
                    //当断开连接，并不会跳出while循环，所以改成以下写法
                }
            }*/
            try {
                while (true) {
                    String message = dis.readUTF();
                    Log.i("info","message:"+message);
                    //更新ListView，给handler发消息
                    Message msg = new Message();
                    msg.what = HANDLER_MESSAGE_RECEIVED;
                    msg.obj = message;
                    handler.sendMessage(msg);
                }
            } catch (IOException e) {
                e.printStackTrace();
                //连接异常，断开
                Log.e("error", "连接出错，读不了数据了，看着办吧");
            }
        }
    }

    private void connect() throws IOException {
        String ip = et_ip.getText().toString();
        socket = new Socket(ip, 8888);

        dis = new DataInputStream(socket.getInputStream());
        dos = new DataOutputStream(socket.getOutputStream());
        //连接成功，发消息给主线程Handler 更新UI
        handler.sendEmptyMessage(HANDLER_CONNECT_SUCCESS);
        //启动读取消息的工作线程
        new ReadThread().start();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(socket!=null){
            try {
                //socket关掉后，流也就关掉了
                //而客户端还有线程正等着读取数据，所以也需要处理下
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

增加权限
AndroidManifest

    <uses-permission android:name="android.permission.INTERNET"/>

运行步骤
1、用Eclipse运行ChatServer

2、查看自己电脑ip
cmd中执行ipconfig

3、修改MainActivity中，以下代码，把message前增加一个称呼，例如“小明”，运行在一台模拟机中

private void sendMessage() throws IOException {
        String text = et_message.getText().toString();
        dos.writeUTF("小红：\n"+text);
        dos.flush();
    }

输入刚才的ip地址，保证连接成功

4、修改MainActivity中3步骤代码中的称呼，改为“小红”，运行在另一台模拟机中，输入相同ip保证连接成功

5、开始尬聊