Android socket 实现　wify 通信，简易聊天室 (一）

功能简介：

实现移动端Client连接上PC的wify后，实现与PC 上运行的Server进行简单的通信．

基础知识：

１）java 多线程机制

２）Handler消息传递机制

３）socket

４）Printstream,Bufferreader,readline()

５）Android 简单使用

代码：

服务器：

//MyServer.java

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

import org.omg.CORBA.SystemException;

public class MyServer {

private static final int PORT = 5000; //spy on the port 5000

void initMyserver() {
try {
ServerSocket serverSocket = new ServerSocket(PORT);

while(true) {
System.out.println("available");

//If there is not connect,it will block.
//Listen to the connect from client.
//If there is a connect ,it will return a socket.
Socket socket = serverSocket.accept();

//build a thread to deal with the socket
Thread thread = new Thread(new ServerThread(socket));
thread.start();
}
} catch (IOException e) {
// TODO: handle exception
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
MyServer myServer = new MyServer();
myServer.initMyserver();
}

}

//ServerThread.java

import java.awt.print.PrinterGraphics;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.nio.Buffer;
import java.text.SimpleDateFormat;
import java.util.Date;

public class ServerThread implements Runnable {

Socket socket;
  PrintStream output;
BufferedReader in;


public ServerThread(Socket socket) throws IOException {
this.socket = socket;
}

//broadcast the message from one client to every clients
public void run() {

String buffer;
try {

in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
output = new PrintStream(socket.getOutputStream());

     buffer = ""; //if init buffer = null, will get a string which like "null..."
String line = null;

//Read message From readline.
//Here , You must be careful, because readline() will block rather than return null
//if there is no input.Readline() will return  when you close the stream,such as
//socket.shutdownOutput();
while ((line = in.readLine()) != null) {
buffer = buffer + line;
//System.out.println(buffer); 
output.println(packetMessage(buffer)); 
output.flush(); 
}

//You can replace the code of "Read message From readline " by follow,
//but you can not output to client after you shutdown output.
//while((line = in.readLine()) != null) {
//buffer = buffer + line;
//}
//output.println(packetMessage(buffer));
//output.flush();
//  socket.shutdownOutput();

//System.out.println(buffer);

} catch (IOException e) {
// TODO: handle exception
e.printStackTrace();
}
}

public String packetMessage(String buffer) {
String result = null;
SimpleDateFormat dFormat = new SimpleDateFormat("HH:mm:ss");
result = "Form server:  "+dFormat.format(new Date())+" "+buffer;
return result;
}
}

客户端代码：

package com.example.yifeihappy.talkingroom;

import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.net.Inet4Address;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.util.concurrent.TimeoutException;

public class MainActivity extends AppCompatActivity {

    private String HOST = "125.216.250.3";//computer IP
    private int PORT = 5000; //server PORT,the same to server
    private String buffer;
    PrintStream output;
    BufferedReader in;
    EditText edtMessage;
    TextView tvContent;
    Button btnSend;
    Socket socket;
    MyHandler myHandler = new MyHandler();

    class MyHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            Bundle bundle = msg.getData();
            String buffer = bundle.getString("newcontent");
            tvContent.append('\n' + buffer);

        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tvContent = (TextView)findViewById(R.id.content);
        btnSend = (Button)findViewById(R.id.send);
        edtMessage = (EditText)findViewById(R.id.message);

        btnSend.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                String str = edtMessage.getText().toString();
                new ClientThread(str).start();

            }
        });


    }

    class  ClientThread extends Thread {
        String str;

        public ClientThread (String str) {
            this.str = str;
        }

        @Override
        public void run() {


            Message ms = myHandler.obtainMessage();
            Bundle bundle = new Bundle();
            bundle.clear();



            //build socket conncetion.
            try {
                socket = new Socket();
                socket.connect(new InetSocketAddress(HOST,PORT),5000);

                in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                output = new PrintStream(socket.getOutputStream());

                output.println(str);
                output.flush();

                String line = null;
                buffer = "";
                while ((line = in.readLine()) != null) {
                    buffer = buffer + line;
                    if(buffer!=null) {
                        bundle.putString("newcontent",buffer);
                        ms.setData(bundle);
                        myHandler.sendMessage(ms);
                    }
                }
            }
            catch (SocketTimeoutException aa)
            {
                bundle.putString("newcontent","There is Timeout");
                ms.setData(bundle);
                myHandler.sendMessage(ms);

            }
            catch (IOException e) {

                bundle.putString("newcontent","There is IOEX");
                ms.setData(bundle);
                myHandler.sendMessage(ms);

            }

            try {

                output.close();
                in.close();
                socket.close();
            }
            catch (IOException e) {
                bundle.putString("newcontent","There is IOEX close");
                ms.setData(bundle);
                myHandler.sendMessage(ms);

            }
        }

    }

}

注意:

要在 AndroidManifest.xml 下添加用户权限：

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

运行：

这里我把server建立在eclipse，将Myserver项目当做java applications 运行．

逻辑思路是：运行server,用于监听client的请求．如果没有请求，则在accept()处阻塞等待请求．当有Client建立链接时则产生一个socket,并新建一个线程与Client交互．

具体的交互为建立socket链接后Server在readline()处等待Client的输入并阻塞，Client有消息传递时处理并及时返回．

用户通过EditText输入并点击send Button,这时创建一个线程，在线程中产生一个socket与Server链接．Client向Server发送一个数据，并在发送一个数据后由于readline()无数据输入而阻塞，等待从Server处获取数据，在取得Server返回的数据后利用Handler处理UI,显示返回结果．

注意：

手机连接笔基本的wify,

代码中HOST为你电脑IP.

效果图：

常见问题与解决：

Problems:Client 无法从Server 获取数据　或　Server无法获取Client数据

Analyse:很有可能是没有了解readline()的使用方法造成的问题．

这里要记住：readline()不是当没有输入的时候返回null．readline()当没有数据时会阻塞，在数据流异常或断开时才会返回null．

例如：把Client的原代码

 <span style="font-size:14px;">               output.println(str);
                output.flush();

                String line = null;
                buffer = "";
                while ((line = in.readLine()) != null) {
                    buffer = buffer + line;
                    if(buffer!=null) {
                        bundle.putString("newcontent",buffer);
                        ms.setData(bundle);
                        myHandler.sendMessage(ms);
                    }
                }</span>

改为

<span style="font-size:14px;">                output.println(str);
                output.flush();

                String line = null;
                buffer = "";
                while ((line = in.readLine()) != null) {
                    buffer = buffer + line;
                    }</span>
                }

<pre name="code" class="html"><span style="font-size:14px;">                    if(buffer!=null) {
                        bundle.putString("newcontent",buffer);
                        ms.setData(bundle);
                        myHandler.sendMessage(ms);</span>

这样就会导致UI无法更新，也就是无法看到Server的返回结果．因为readline()一直不会返回null,除非将Server的原代码

while ((line = in.readLine()) != null) {
buffer = buffer + line;
//System.out.println(buffer); 
output.println(packetMessage(buffer)); 
output.flush(); 
}

改为

while ((line = in.readLine()) != null) {
buffer = buffer + line;
//System.out.println(buffer); 
output.println(packetMessage(buffer)); 
output.flush(); 
socket.shutdownOutput();
}

也就是在每个循环末尾执行socket.shutdownOutput().不过导致每次提交都只能读一行（readline()的功能造成的）．