Android设备间通信（wifi连接）

基于TCP/IP协议实现：

1、首先在服务端新建ServerSocket类，指定端口号，利用其获取连接信息，得到Socket，之后的数据接收与发送，就可以通过这个Socket来进行实现。

server端主程序

package aw.com.wifi_connect_server;import android.app.Activity;import android.content.Context;import android.net.ConnectivityManager;import android.net.NetworkInfo;import android.net.wifi.WifiInfo;import android.net.wifi.WifiManager;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.ServerSocket;import java.net.Socket;public class MainActivity extends AppCompatActivity {    private TextView server_ip_port;    private TextView client_ip_port;    private TextView sendData;    private String msg_send;    private EditText message;    private ServerSocket serverSocket = null;    StringBuffer stringBuffer = new StringBuffer();    private InputStream inputStream;    private String IP=null;    private int Port=0;    private String clientIp;    private int clientPort;    private Socket socket = null;    public Handler handler = new Handler(){        @Override        public void handleMessage(Message msg) {            //super.handleMessage(msg);            switch (msg.what){                case 1:                    server_ip_port.setText(msg.obj.toString());                    break;                case 2:                    message.setText(msg.obj.toString());                    stringBuffer.setLength(0);                    break;                case 3:                    client_ip_port.setText(msg.obj.toString());                    break;            }        }    };        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                server_ip_port = (TextView) findViewById(R.id.server);        client_ip_port = (TextView) findViewById(R.id.client);        message = (EditText) findViewById(R.id.message_get);        sendData = (EditText) findViewById(R.id.send_data);        receiveData();    }    /*    服务器端接收数据    需要注意以下一点：    服务器端应该是多线程的，因为一个服务器可能会有多个客户端连接在服务器上；    */    private void receiveData() {        Thread thread = new Thread(){            @Override            public void run() {                super.run();                /*指明服务器端的端口号*/                try {                    serverSocket = new ServerSocket(8091);                } catch (IOException e) {                    e.printStackTrace();                }                if (serverSocket!=null && !serverSocket.isClosed()){                    Port = serverSocket.getLocalPort();                }                WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);                int state = wifiManager.getWifiState();                if (state == 3) {                    WifiInfo info = wifiManager.getConnectionInfo();                    IP = intIP2StringIP(info.getIpAddress());                    Message message_1 = handler.obtainMessage();                    message_1.what = 1;                    message_1.obj = "IP:" + IP + " PORT: " + Port;                    handler.sendMessage(message_1);                    while (true) {                        try {                            if (serverSocket != null && !serverSocket.isClosed()) {                                socket = serverSocket.accept();                                clientIp = socket.getInetAddress().toString();                                clientIp = clientIp.substring(1,clientIp.length());                                clientPort = socket.getPort();                                Message message_3 = handler.obtainMessage();                                message_3.what = 3;                                message_3.obj = "IP:" + clientIp + " PORT:" + clientPort;                                handler.sendMessage(message_3);                                inputStream = socket.getInputStream();                                new ServerThread(socket, inputStream).start();                            }                        } catch (IOException e) {                            e.printStackTrace();                        }                    }                }            }        };        thread.start();    }    private String intIP2StringIP(int ip) {        return (ip & 0xFF) + "." + ((ip >> 8) & 0xFF) + "." + ((ip >> 16) & 0xFF) + "." + ((ip >> 24) & 0xFF);    }    public void send(View view){        msg_send = sendData.getText().toString();        if (msg_send.isEmpty()){            Toast.makeText(MainActivity.this, "Please input Sending data", Toast.LENGTH_SHORT).show();        }        msg_send = msg_send + "\0";        Thread thread = new Thread() {            @Override            public void run() {                super.run();                try {                    OutputStream outputStream = socket.getOutputStream();                    outputStream.write(msg_send.getBytes());                } catch (IOException e) {                    e.printStackTrace();                }            }        };        thread.start();    }    class ServerThread  extends Thread{        private Socket socket;        private InputStream   inputStream;        private StringBuffer stringBuffer = MainActivity.this.stringBuffer;        public ServerThread(Socket socket,InputStream inputStream){            this.socket = socket;            this.inputStream = inputStream;        }        @Override        public void run() {            int len;            byte[] bytes = new byte[20];            boolean isString = false;            try {                //在这里需要明白一下什么时候其会等于 -1，其在输入流关闭时才会等于 -1，                //并不是数据读完了，再去读才会等于-1，数据读完了，最结果也就是读不到数据为0而已；                while ((len = inputStream.read(bytes)) != -1) {                    for(int i=0; i

server端页面

2、客户端，需知道服务器端的IP地址与端口号，然后才能依据server端的IP和端口号与server端建立连接，得到Socket，建立连接后，数据的接收与发送同样依赖于这一Socket。

client端主程序

package aw.com.wifi_connect_client;import android.content.Context;import android.net.wifi.WifiManager;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.ServerSocket;import java.net.Socket;import java.net.UnknownHostException;public class MainActivity extends AppCompatActivity {    private EditText et_IP, et_data;    private TextView local_ip_port;    private String localIP;    private int localPort;    private OutputStream outputStream = null;    private Socket socket = null;    private String IP;    private String data;    private boolean socketStatus = false;    private EditText message;    private StringBuffer stringBuffer = new StringBuffer();    private InputStream inputStream;    public Handler handler = new Handler() {        @Override        public void handleMessage(Message msg) {            //super.handleMessage(msg);            switch (msg.what) {                case 1:                    local_ip_port.setText(msg.obj.toString());                    break;                case 2:                    message.setText(msg.obj.toString());                    stringBuffer.setLength(0);                    break;            }        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        et_IP = (EditText) findViewById(R.id.et_ip);        et_data = (EditText) findViewById(R.id.et_data);        local_ip_port = (TextView) findViewById(R.id.local_ip_port);        message = (EditText) findViewById(R.id.message_get);    }    public void connect(View view) {        IP = et_IP.getText().toString();        if (IP.isEmpty()) {            Toast.makeText(MainActivity.this, "Please input Server IP", Toast.LENGTH_SHORT).show();        }        Thread thread = new Thread() {            @Override            public void run() {                super.run();                WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);                int state = wifiManager.getWifiState();                if (!socketStatus && state == 3) {                    try {                        socket = new Socket(IP, 8091);                        if (socket != null && !socket.isClosed()) {                            localIP = socket.getLocalAddress().toString();                            localIP = localIP.substring(1, localIP.length());                            localPort = socket.getLocalPort();                            Message message_1 = handler.obtainMessage();                            message_1.what = 1;                            message_1.obj = "IP:" + localIP + " PORT:" + localPort;                            handler.sendMessage(message_1);                            socketStatus = true;                            outputStream = socket.getOutputStream();                            receiveData();  //建立连接后，才可进行数据发送与数据接收                        }                    } catch (IOException e) {                        e.printStackTrace();                    }                }            }        };        thread.start();    }    public void send(View view) {        data = et_data.getText().toString();        if (data.isEmpty()) {            Toast.makeText(MainActivity.this, "Please input Sending Data", Toast.LENGTH_SHORT).show();        }        data = data + "\0";        Thread thread = new Thread() {            @Override            public void run() {                super.run();                if (socketStatus) {                    try {                        outputStream.write(data.getBytes());                    } catch (IOException e) {                        e.printStackTrace();                    }                }            }        };        thread.start();    }    /**     * 接收数据     */    private void receiveData() {        Thread thread = new Thread() {            @Override            public void run() {                super.run();                try {                    inputStream = socket.getInputStream();                    new ServerThread(socket, inputStream).start();                } catch (IOException e) {                    e.printStackTrace();                }            }        };        thread.start();    }    class ServerThread extends Thread{        private Socket socket;        private InputStream inputStream;        private StringBuffer stringBuffer = MainActivity.this.stringBuffer;        public ServerThread(Socket socket, InputStream inputStream) {            this.socket = socket;            this.inputStream = inputStream;        }        @Override        public void run() {            int len;            byte[] bytes = new byte[20];            boolean isString = false;            try {                //在这里需要明白一下什么时候其会等于 -1，其在输入流关闭时才会等于 -1，                //并不是数据读完了，再去读才会等于-1，数据读完了，最结果也就是读不到数据为0而已；                while ((len = inputStream.read(bytes)) != -1) {                    for(int i=0; i

客户端页面

server端与client端页面效果

注意事项：

由于使用到了网络，故需要添加相应的权限，若缺少可能会出现如下错误

10-12 20:09:03.680 23977-24056/aw.com.wifi_connect_server W/System.err: java.net.SocketException: Permission denied
10-12 20:09:03.681 23977-24056/aw.com.wifi_connect_server W/System.err:     at java.net.ServerSocket.createImpl(ServerSocket.java:309)
10-12 20:09:03.681 23977-24056/aw.com.wifi_connect_server W/System.err:     at java.net.ServerSocket.getImpl(ServerSocket.java:258)
10-12 20:09:03.681 23977-24056/aw.com.wifi_connect_server W/System.err:     at java.net.ServerSocket.bind(ServerSocket.java:377)
10-12 20:09:03.681 23977-24056/aw.com.wifi_connect_server W/System.err:     at java.net.ServerSocket.<init>(ServerSocket.java:237)
10-12 20:09:03.681 23977-24056/aw.com.wifi_connect_server W/System.err:     at java.net.ServerSocket.<init>(ServerSocket.java:128)
10-12 20:09:03.681 23977-24056/aw.com.wifi_connect_server W/System.err:     at aw.com.wifi_connect_server.MainActivity$2.run(MainActivity.java:71)

在server与client的AndroidManifest.xml中添加相应权限

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