Android14_IPC方式之Socket

Socket也叫做“套接字”；是网络通信中的概念；

分为流式套接字和用户数据报套接字两种，分别对应于网络的传输控制层的TCP和UDP协议；

TCP协议是面向连接的协议，提供稳定的双向通信功能；本身具有超时重传功能，非常稳定；

UDP是无连接的，提供不稳定的单向通信功能，UDP也是可以实现双向通信功能；UDP具有更好的效率，缺点是不保证数据一定能够正确传输；

使用Socket来通信，有两点需要注意，首先需要声明权限：

注意不能在主线程中访问网络，这会导致我们的程序无法在Android4.0及以上的设备中运行，会抛出异常；

网络操作可能比较耗时，如果在主线程中运行会影响程序的响应效率。

1、先看一下Manifest的设置：

这里为了演示方便，还是使用一个应用，多进程模式。Service单独作为一个进程；

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.learnsocket">
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <service
            android:name=".TCPService"
            android:enabled="true"
            android:exported="true"
            android:process=":TCPService"></service>

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

2、客户端的代码：

package com.example.learnsocket;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private static final String TAG = "Client";
    private static final int MESSAGE_RECEIVE_NEW_MSG = 1;
    private static final int MESSAGE_SOCKET_CONNECTED = 2;

    private Button mSendButton;
    private TextView mMessageTextView;
    private EditText mMessageEditText;

    private PrintWriter mPrintWriter;
    private Socket mClientSocket;

    @SuppressLint("HandlerLeak")
    private Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg){
            switch(msg.what){
                case MESSAGE_RECEIVE_NEW_MSG:{   //新消息
                    mMessageTextView.setText(mMessageTextView.getText()+(String)msg.obj);
                    break;
                }
                case MESSAGE_SOCKET_CONNECTED:{  //连接成功
                    mSendButton.setEnabled(true);
                    break;
                }
                default:
                    break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mMessageEditText = (EditText)findViewById(R.id.input);
        mMessageTextView = (TextView)findViewById(R.id.msgwindow);
        mSendButton = (Button)findViewById(R.id.sendbutton);
        mSendButton.setOnClickListener(this);

        Intent connectintent = new Intent(this,TCPService.class);
        startService(connectintent);
        new Thread(){
            @Override
            public void run(){
                connectTCPServer();
            }
        }.start();
    }

    private void connectTCPServer(){
        Socket socket = null;
        while(socket == null){
            try{
                socket = new Socket("localhost",8688);
                mClientSocket = socket;
                mPrintWriter = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);
                mHandler.sendEmptyMessage(MESSAGE_SOCKET_CONNECTED);
                Log.d(TAG,"connected server success");
            }catch(IOException e){
                SystemClock.sleep(1000);
                Log.d(TAG,"connect tcp server failed,retry...");
            }
        }

        try{
            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            while(!MainActivity.this.isFinishing()){
                String msg = br.readLine();
                Log.d(TAG,"receive :"+msg);
                if(msg != null){
                    String time = formatDateTime(System.currentTimeMillis());
                    final String showedMsg = "server "+time+":"+msg+"
";
                    mHandler.obtainMessage(MESSAGE_RECEIVE_NEW_MSG,showedMsg).sendToTarget();
                }
            }
            Log.d(TAG,"quit...");
            mPrintWriter.close();
            br.close();
            socket.close();
        }catch(IOException e){
            e.printStackTrace();
        }


    }

    @Override
    protected void onDestroy(){
        if(mClientSocket != null){
            try{
                mClientSocket.shutdownInput();
                mClientSocket.close();
            }catch(IOException e){
                e.printStackTrace();
            }
        }
        super.onDestroy();
    }

    @Override
    public void onClick(View v){
        if(v == mSendButton){
            final String msg = mMessageEditText.getText().toString();
            if(!TextUtils.isEmpty(msg) && mPrintWriter !=null){
                new Thread(){
                    @Override
                    public void run(){
                        mPrintWriter.println(msg);
                    }
                }.start();
                mMessageEditText.setText("");
                String time = formatDateTime(System.currentTimeMillis());
                final String showedMsg = "self "+ time + ":" + msg + "
";
                mMessageTextView.setText(mMessageTextView.getText()+showedMsg);
            }
        }
    }

    @SuppressLint("SimpleDateFormat")
    private String formatDateTime(long time){
        return new SimpleDateFormat("(HH:mm:ss)").format(new Date(time));
    }
}

3、服务端的代码：

package com.example.learnsocket;

import android.annotation.SuppressLint;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Random;


public class TCPService extends Service {
    private static final String TAG = "TCPService";
    private boolean mIsServiceDestroyed = false;
    private String[] mDefinedMessages = new String[] {
            "你好啊，哈哈",
            "请问你叫什么名字呀？",
            "今天北京天气不错啊，shy",
            "你知道吗？我可是可以和多个人同时聊天的哦",
            "给你讲个笑话吧：据说爱笑的人运气不会太差，不知道真假。"
    };

    @Override
    public void onCreate(){
        new Thread(new TcpServer()).start();
        super.onCreate();
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }


    @Override
    public void onDestroy(){
        mIsServiceDestroyed = true;
        super.onDestroy();
    }


    public TCPService() {
    }


    private class TcpServer implements Runnable{
        @SuppressLint("resource")
        @Override
        public void run(){
            ServerSocket serverSocket = null;
            try{
                //监听本地8688端口
                serverSocket =new ServerSocket(8688);
            }catch(IOException e){
                Log.d(TAG,"establish tcp server failed, port:8688");
                e.printStackTrace();
                return;
            }

            while(!mIsServiceDestroyed){
                try{
                    //接收客户端请求
                    final Socket client = serverSocket.accept();
                    Log.d(TAG,"accept");
                    new Thread() {
                        @Override
                        public void run() {
                            try {
                                responseClient(client);
                            }catch(IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }.start();
                }catch(IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private void responseClient(Socket client)throws IOException {
        //用于接收客户端消息
        BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
        //用于向客户端发送消息
        PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(client.getOutputStream())),true);
        out.println("欢迎来到聊天室");
        while(!mIsServiceDestroyed){
            String str = in.readLine();
            Log.d(TAG,"msg from client: "+str);
            if(str == null){
                break;
            }
            int i = new Random().nextInt(mDefinedMessages.length);
            String msg = mDefinedMessages[i];
            out.println(msg);
            Log.d(TAG,"send :"+msg);
        }
        Log.d(TAG,"client quit.");
        in.close();
        out.close();
        client.close();

    }
}

4、activity的布局文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/sendbutton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.89"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/msgwindow" />

    <TextView
        android:id="@+id/msgwindow"
        android:layout_width="match_parent"
        android:layout_height="592dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.13999999" />

    <EditText
        android:id="@+id/input"
        android:layout_width="260dp"
        android:layout_height="51dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/sendbutton"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/msgwindow" />

</androidx.constraintlayout.widget.ConstraintLayout>