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
<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">
<Button android:text="send"
android:id="@+id/Button02"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
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
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();
}
}
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
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);
