见证Android消息推送时刻--笔记---Socket即时通讯机制

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前几天在"慕课网"看到了郭霖大神的视频----点击打开链接

"见证Android消息推送时刻",由于自己这段时间也在做即时通讯,作为初级码农,顿时感到与大神如此的接近,所以决定追随大神的步伐,把郭神的每一段代码,每一句话都记下来认真学习,笔记分享给大家,一起学习.

1 IM通讯机制研究

长连接短连接

即时通讯属于长连接,维护一个服务,一直监听消息的到达

2 实现在控制台输出内容在服务端接收

----客户端代码:这个类实现了控制台输出文本

 /** * 消息推送机制客户端代码 * @author fflin learned by GuoLin * */public class SocketClient {

      public static void main(String[] args) {        /**         * 实现用户在命令行输出消息         */        SocketClient socketClient = new SocketClient();        socketClient.start();            }    public void start(){        BufferedReader inBufferedReader;        try {            inBufferedReader = new BufferedReader(new InputStreamReader(System.in));            String inputContent;            while(!(inputContent = inBufferedReader.readLine()).equals("bye")){                System.out.println(inputContent);            }        } catch (Exception e) {             // TODO Auto-generated catch block            e.printStackTrace();        }    }

----服务端代码:接收客户端消息

        public class SocketServer {        public static void main(String[] args) {            SocketServer mSocketServer = new SocketServer();            mSocketServer.start();        }        public void start(){            ServerSocket mServerSocket;             BufferedReader reader;            /**             * 创建ServerSocket对象,参数是端口号,             * accept方法表示阻塞服务,等待客户端接入             */            try {                mServerSocket = new ServerSocket(9998);                Socket mSocket = mServerSocket.accept();                reader = new BufferedReader(new InputStreamReader(mSocket.getInputStream()));                /**                 * 客户端发送过来的消息                 */                String receivedMessage;                while((receivedMessage = reader.readLine()) != null){                    System.out.println(receivedMessage);                }                            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }}

-----客户端创建Socket消息对象,通过创建输出流,发送消息到服务器

 //创建服务器的Socket连接,参数:IP地址,端口号            socket = new Socket("127.0.0.1",9998);            //发送消息            writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));            inBufferedReader = new BufferedReader(new InputStreamReader(System.in));            String inputContent;            while(!(inputContent = inBufferedReader.readLine()).equals("bye")){                writer.write(inputContent+"\n");                writer.flush();                System.out.println(inputContent);            }

----服务端接收到消息,打印到控制台

 mServerSocket = new ServerSocket(9998);                System.out.println("服务启动了....");                Socket mSocket = mServerSocket.accept();                System.out.println("客户端:"+mSocket.hashCode()+"已经连接服务器");

-----服务端接收到消息,打印

-----目前实现了从客户端发送消息给服务端,如果要实现服务端发送消息到客户端,只需要把服务端和客户端的reader和writer替换

---服务端创建writer对象,回复客户端消息

writer = new BufferedWriter(new OutputStreamWriter(mSocket.getOutputStream()));

---客户端创建reader,接收服务端消息

reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));

3 问题:

目前虽然实现了客户端与服务端的长连接,可是客户端不能被动接受服务端的消息,只能主动发送消息到服务器,才会收到服务器返回的消息

4 完善优化Socket消息机制

---客户端开启服务器消息监听器,目前客户端已经拥有了随时接受服务端返回消息的能力

public void startServerReplyListener(final BufferedReader reader){

//请求网络等耗时操作要放在子线程中运行

new Thread(new Runnable() {

@Override

public void run() {

try {

String response;

//相当于子线程阻塞,一直监听服务器的消息到达

while((response = reader.readLine()) != null){

System.out.println(response);

}

} catch (IOException e) {

e.printStackTrace();

}

}).start();

}

-----定时任务

-----注意一个问题,在读取数据的操作中,程序判断以"\n"(换行符)为一段文本的结束

5 服务端目前存在的问题:只允许一个客户端接入

public void manageConnection(Socket socket){

//为每个建立连接的Socket建立一个线程,进行管理

new Thread(new Runnable() {

@Override

public void run() {

try {

reader = new BufferedReader(new InputStreamReader(mSocket.getInputStream()));

writer = new BufferedWriter(new OutputStreamWriter(mSocket.getOutputStream()));

/**

* 客户端发送过来的消息

String receivedMessage;

while((receivedMessage = reader.readLine()) != null){

System.out.println(receivedMessage);

//服务器收到消息,回复给客户端,注意加换行符

writer.write("服务端收到消息,回复:"+receivedMessage+"\n");

writer.flush();

}

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally{

try {

reader.close();

writer.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}).start();

-----调用管理客户端接入的方法

while (true) {

mSocket = mServerSocket.accept();

manageConnection(mSocket);

System.out.println("客户端:" + mSocket.hashCode() + "已经连接服务器");

}

----运行效果

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