android socket编程实例
android客户端通过socket与服务器进行通信可以分为以下几步：
应用程序与服务器通信可以采用两种模式：TCP可靠通信 和UDP不可靠通信。
（1）通过IP地址和端口实例化Socket，请求连接服务器：
socket = new Socket(HOST, PORT); //host:为服务器的IP地址 port：为服务器的端口号
（2）获取Socket流以进行读写，并把流包装进BufferWriter或者PrintWriter：
PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);
这里涉及了三个类：socket.getOutputStream得到socket的输出字节流，OutputStreamWriter是字节流向字符流转换的桥梁，BufferWriter是字符流，然后再包装进PrintWriter。
（3）对Socket进行读写
if (socket.isConnected()) { if (!socket.isOutputShutdown()) { out.println(msg); } }
（4）关闭打开的流
out.close();
在写代码的过程中一定要注意对socket 输入流 输出流的关闭
下面是一个简单的例子：
main.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <TextView android:id="@+id/TextView" android:singleLine="false" android:layout_width="fill_parent" android:layout_height="wrap_content" /> <EditText android:hint="content" android:id="@+id/EditText01" android:layout_width="fill_parent" android:layout_height="wrap_content"> </EditText> <Button android:text="send" android:id="@+id/Button02" android:layout_width="fill_parent" android:layout_height="wrap_content"> </Button> </LinearLayout>
下面是android客户端的源代码：
package com.android.SocketDemo; 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 android.app.Activity; import android.app.AlertDialog; import android.content.DialogInterface; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class SocketDemo extends Activity implements Runnable { private TextView tv_msg = null; private EditText ed_msg = null; private Button btn_send = null; // private Button btn_login = null; private static final String HOST = "192.168.1.223"; private static final int PORT = 9999; private Socket socket = null; private BufferedReader in = null; private PrintWriter out = null; private String content = ""; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); tv_msg = (TextView) findViewById(R.id.TextView); ed_msg = (EditText) findViewById(R.id.EditText01); // btn_login = (Button) findViewById(R.id.Button01); btn_send = (Button) findViewById(R.id.Button02); try { socket = new Socket(HOST, PORT); in = new BufferedReader(new InputStreamReader(socket.getInputStream())); out = new PrintWriter(new BufferedWriter(new OutputStreamWriter( socket.getOutputStream())), true); } catch (IOException ex) { ex.printStackTrace(); ShowDialog("login exception" + ex.getMessage()); } btn_send.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub String msg = ed_msg.getText().toString(); if (socket.isConnected()) { if (!socket.isOutputShutdown()) { out.println(msg); } } } }); //启动线程，接收服务器发送过来的数据 new Thread(SocketDemo.this).start(); } //如果连接出现异常，弹出AlertDialog！ public void ShowDialog(String msg) { new AlertDialog.Builder(this).setTitle("notification").setMessage(msg) .setPositiveButton("ok", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub } }).show(); } //读取服务器发来的信息，并通过Handler发给UI线程 public void run() { try { while (true) { if (socket.isConnected()) { if (!socket.isInputShutdown()) { if ((content = in.readLine()) != null) { content += "\n"; mHandler.sendMessage(mHandler.obtainMessage()); } else { } } } } } catch (Exception e) { e.printStackTrace(); } } //接收线程发送过来信息，并用TextView显示 public Handler mHandler = new Handler() { public void handleMessage(Message msg) { super.handleMessage(msg); tv_msg.setText(tv_msg.getText().toString() + content); } }; }
下面是服务器端得java代码：
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.ArrayList; import java.util.List; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class Main { private static final int PORT = 9999; private List<Socket> mList = new ArrayList<Socket>(); private ServerSocket server = null; private ExecutorService mExecutorService = null; //thread pool public static void main(String[] args) { new Main(); } public Main() { try { server = new ServerSocket(PORT); mExecutorService = Executors.newCachedThreadPool(); //create a thread pool System.out.print("服务器已启动..."); Socket client = null; while(true) { client = server.accept(); //把客户端放入客户端集合中 mList.add(client); mExecutorService.execute(new Service(client)); //start a new thread to handle the connection } }catch (Exception e) { e.printStackTrace(); } } class Service implements Runnable { private Socket socket; private BufferedReader in = null; private String msg = ""; public Service(Socket socket) { this.socket = socket; try { in = new BufferedReader(new InputStreamReader(socket.getInputStream())); //客户端只要一连到服务器，便向客户端发送下面的信息。 msg = "user" +this.socket.getInetAddress() + "come toal:" +mList.size(); this.sendmsg(); } catch (IOException e) { e.printStackTrace(); } } @Override public void run() { // TODO Auto-generated method stub try { while(true) { if((msg = in.readLine())!= null) { //当客户端发送的信息为：exit时，关闭连接 if(msg.equals("exit")) { System.out.println("ssssssss"); mList.remove(socket); in.close(); msg = "user:" + socket.getInetAddress() + "exit total:" + mList.size(); socket.close(); this.sendmsg(); break; //接收客户端发过来的信息msg，然后发送给客户端。 } else { msg = socket.getInetAddress() + ":" + msg; this.sendmsg(); } } } } catch (Exception e) { e.printStackTrace(); } } //循环遍历客户端集合，给每个客户端都发送信息。 public void sendmsg() { System.out.println(msg); int num =mList.size(); for (int index = 0; index < num; index ++) { Socket mSocket = mList.get(index); PrintWriter pout = null; try { pout = new PrintWriter(new BufferedWriter( new OutputStreamWriter(mSocket.getOutputStream())),true); pout.println(msg); }catch (IOException e) { e.printStackTrace(); } } } } }
注意在AndroidManifest.xml中加入对网络的访问权限
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
在写代码的过程中一定要注意对套接字和输入/输出流的关闭
解析：除了isClose方法，Socket类还有一个isConnected方法来判断Socket对象是否连接成功。 看到这个名字，也许读者会产生误解。 其实isConnected方法所判断的并不是Socket对象的当前连接状态， 而是Socket对象是否曾经连接成功过，如果成功连接过，即使现在isClose返回true， isConnected仍然返回true。因此，要判断当前的Socket对象是否处于连接状态， 必须同时使用isClose和isConnected方法， 即只有当isClose返回false，isConnected返回true的时候Socket对象才处于连接状态。 虽然在大多数的时候可以直接使用Socket类或输入输出流的close方法关闭网络连接，但有时我们只希望关闭OutputStream或InputStream，而在关闭输入输出流的同时，并不关闭网络连接。这就需要用到Socket类的另外两个方法：shutdownInput和shutdownOutput，这两个方法只关闭相应的输入、输出流，而它们并没有同时关闭网络连接的功能。和isClosed、isConnected方法一样，Socket类也提供了两个方法来判断Socket对象的输入、输出流是否被关闭，这两个方法是isInputShutdown()和isOutputShutdown()。 shutdownInput和shutdownOutput并不影响Socket对象的状态。
super.onCreate(savedInstanceState);
// android3.0以后需要加入以下的代码，否则会报socket连接异常的错误
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());
StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().penaltyLog().penaltyDeath().build());
setContentView(R.layout.activity_login);
