Android多個Activity共享socket，實現一個頁面連接WIFI，其他頁面也能傳輸數據

Android多個頁面共享socket的方法有三種：
1.單例模式
2.Application實體類
3.socket封裝在service中
這裏只用了第二種方法，即封裝一個Application實體類。具體實現如下：

package com.example.wisdomclassroom;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Application;
import android.os.Looper;
import android.util.Log;
import android.widget.Toast;

public class WiFiApplication extends Application {
    private static Socket socket;
    private static OutputStream out = null;
    private static InputStream in = null;
    private  static String IP = "192.168.4.1";
    private  static int PORT = 8080;
    private static boolean Connect_flag;
    private static String msg_send;
    public void init() throws IOException, Exception{
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    if(socket==null) {
                        socket = new Socket(IP, PORT);
                        out = new DataOutputStream(socket.getOutputStream());
                        in = new DataInputStream(socket.getInputStream());
                        Connect_flag = true;
                        Log.d("slllllll", "789789789789");
                    }
                    else if(socket!=null){
                        socket.close();
                        socket = null;
                        Connect_flag = false;
                        Log.d("slllllll", "7123123322626");
                    }
                } catch (UnknownHostException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    public void SendData() throws IOException{
        new Thread(new Runnable() {
            @Override
            public void run() {
                if(socket != null){
                    try{
                        if (msg_send != null && msg_send.length()>0){
                            out.write(msg_send.getBytes("utf-8"));
                            out.flush();
                            msg_send="";
                        }
                    }
                    catch (IOException e){
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }

    public Socket getSocket() { return socket; }

    public void setSocket(Socket socket) { this.socket = socket; }

    public OutputStream getOut() { return out; }

    public void setOut(OutputStream out) { this.out = out; }

    public InputStream getIn() { return in; }

    public void setIn(InputStream in) { this.in = in; }

    public  Boolean getflag(){
        return Connect_flag;
    }

    public void setMsg_send(String msg_send){
        this.msg_send = msg_send;
    }

    public  String getMsg_send(){
        return msg_send;
    }

}

將建立和斷開連接、發送數據都封裝在Application實體類中，當我們在不同Activity中要使用該連接時，只需要先獲取該類的對象，然後調用相應的函數即可。

第一次建立連接

final WiFiApplication WFApp = (WiFiApplication)CatalogActivity.this.getApplication();
        link_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if(socket==null) {
                    try {
                        WFApp.init();
                        socket = WFApp.getSocket();
                        outer = WFApp.getOut();
                        inner = WFApp.getIn();
               }catch (IOException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                if(socket!=null){
                    try {
                        WFApp.init();

                    }catch (IOException e) {
                        e.printStackTrace();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                if(WFApp.getflag()==false) {
                    link_btn.setBackgroundColor(Color.GREEN);
                    link_btn.setText("斷開連接");
                    light_btn.setEnabled(true);
                    fan_btn.setEnabled(true);
                    music_btn.setEnabled(true);
                }
                else if(WFApp.getflag()==true){
                    link_btn.setText("點擊連接");
                    link_btn.setBackgroundColor(Color.GRAY);
                    Toast.makeText(CatalogActivity.this,"連接已斷開",Toast.LENGTH_LONG).show();
                    light_btn.setEnabled(false);
                    fan_btn.setEnabled(false);
                    music_btn.setEnabled(false);
                }
            }
        });

獲取唯一實例

final WiFiApplication WFApp = (WiFiApplication)MusicActivity.this.getApplication();
        socket = WFApp.getSocket();
        outer = WFApp.getOut();

發送數據

     M_playfirst_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                try {
                    msg_send = "music01\n";
                    WFApp.setMsg_send(msg_send);
                    WFApp.SendData();
                    M_play_btn.setBackgroundColor(getResources().getColor(R.color.colorSkyBlue));
                    M_suspend_btn.setBackground(getResources().getDrawable(R.drawable.border_btn));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });