Android设备之间通过Wifi通信

　　之前写过PC与Android之间通过WIFI通信（通过Socket，可以在博客里面搜索），PC作为主机，Android作为客户机，现在手头有一台仪器通过wifi传输数据，如果仪器作为主机发射WIFI热点信号，Android需要连接到该热点才能进一步进行通信，但是由于主机并没有连接到网络，所以在该种情况下Android设备无法使用网络实现相关的网络服务（比如关键数据的上传，网络数据的获取等等），所以仪器在开始设计的时候将其作为客户端，Android设备作为主机（网上的相关资料大多是将Android设备作为客户端），当Android设备开启热点后，仪器会主动尝试连接固定的热点信息，其中网络SSID和密码已经写死了，所以需要手机端手动修改热点名称：

在开启热点之后，此时手机相当于一个路由器，这个路由器的IP地址是固定的（本人测试过3台Android设备，其默认的路由器地址：192.168.43.1，iPhone的默认路由器地址：172.20.10.1），这个Demo主要实现的目标是Android设备客户端发送信息，服务端接受到信息后再发送信息给客户端。那么Android设备创建的SocketServer代码如下：

只有一个按钮，实现在线程中启动相对应的服务，所以在这里就不上图了，直接放代码：

package com.example.socketserver;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import com.koushikdutta.async.callback.CompletedCallback;
import com.koushikdutta.async.http.WebSocket;
import com.koushikdutta.async.http.WebSocket.StringCallback;
import com.koushikdutta.async.http.libcore.RequestHeaders;
import com.koushikdutta.async.http.server.AsyncHttpServer;
import com.koushikdutta.async.http.server.AsyncHttpServer.WebSocketRequestCallback;
import com.koushikdutta.async.http.server.AsyncHttpServerRequest;
import com.koushikdutta.async.http.server.AsyncHttpServerResponse;
import com.koushikdutta.async.http.server.HttpServerRequestCallback;

public class MainActivity extends Activity {
    private Button btnStart;
    private ServerSocket serverSocket;
    private BufferedReader in;
    private PrintWriter out;
    private Handler hander = new Handler(){

        @Override
        public void handleMessage(Message msg) {
            // TODO Auto-generated method stub
            super.handleMessage(msg);
            String s = (String)msg.obj;
            Toast.makeText(MainActivity.this, s, Toast.LENGTH_LONG).show();
        }

    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnStart = (Button)findViewById(R.id.button1);
        btnStart.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new ServerThread().start();//在新线程中启动SocketServer...
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    @Override
    protected void onStop() {
        // TODO Auto-generated method stub
        super.onStop();

    }
    private class ServerThread extends Thread{

        @Override
        public void run() {
            // TODO Auto-generated method stub
            super.run();
            try {
//                serverSocket = new ServerSocket(50005);//默认的路由器地址为Address: 192.168.43.1
                serverSocket = new ServerSocket(5000);
                while (true) {
                    Socket clientSocket = serverSocket.accept();//阻塞等待处理...
                     String remoteIP = clientSocket.getInetAddress().getHostAddress();
                        int remotePort = clientSocket.getLocalPort();
                        System.out.println("A client connected. IP:" + remoteIP+ ", Port: " + remotePort);
                    System.out.println("server: receiving.............");
                    // 获得 client 端的输入输出流，为进行交互做准备
                    in = new BufferedReader(new InputStreamReader(
                            clientSocket.getInputStream()));
                    out = new PrintWriter(clientSocket.getOutputStream(), false);

                    // 获得 client 端发送的数据
                    String tmp = in.readLine();
                    // String content = new String(tmp.getBytes("utf-8"));
                    System.out.println("Client message is: " + tmp);

                    // 向 client 端发送响应数据
                    out.println("Your message has been received successfully！.");

                    // 关闭各个流
                    out.close();
                    in.close();
                     Message message = hander.obtainMessage();
                     message.obj=tmp;
                     hander.sendMessage(message);
                     try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

    }
}

客户端实现的代码与网上相关的资料相差无几，比较简单：

package com.example.serverclient;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
    private Button sendBtn,sendMessageBtn;
    private Socket socket;
    private PrintStream output;
    private BufferedInputStream bufferedInputStream;
    private ReadThread readThread;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sendBtn = (Button) findViewById(R.id.button1);
        sendMessageBtn = (Button) findViewById(R.id.button2);
        sendBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new Thread(runnable).start();//开启线程
            }
        });
        sendMessageBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                 sendMessage("hello,i am from client message");
            }
        });
    }
    Runnable runnable = new Runnable() {

        @Override
        public void run() {
            // TODO Auto-generated method stub
            initClientSocket();
            readThread = new ReadThread();
            readThread.start();
        }
    };

    public void initClientSocket() {
        try {
            socket = new Socket("192.168.43.1", 5000);
            output = new PrintStream(socket.getOutputStream(), true, "gbk");

        } catch (UnknownHostException e) {
            // TODO Auto-generated catch block
            System.out.println("请检查端口号是否为服务器IP");
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            System.out.println("服务器未开启");
            e.printStackTrace();
        }
        output.println("this is the message from client");
    }
    public byte[] receiveData() {
        if (socket == null || socket.isClosed()) {
            try {
                socket = new Socket("192.168.43.1", 5000);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        byte[] data = null;
        if (socket.isConnected()) {
            try {
                bufferedInputStream = new BufferedInputStream(socket.getInputStream());
                data = new byte[bufferedInputStream.available()];
                bufferedInputStream.read(data);
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            data = new byte[1];
        }
        return data;
    }
    private void sendMessage(String str) {
        output.println(str);
    }

    public void closeSocket() {
        try {
            output.close();
            socket.close();
        } catch (IOException e) {
            System.out.println("error"+e);
        }
    }
    private class ReadThread extends Thread{

        @Override
        public void run() {
            // TODO Auto-generated method stub
            super.run();
            while (true) {
                byte[] data = receiveData();
                if (data.length > 1) {
                    System.out.println(new String(data));
                }
            }
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}