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.example.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.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.StrictMode;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
@SuppressLint("NewApi")
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. */
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
@SuppressLint("NewApi")
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_socket_demo);
////Android 2.3及以上调用严苛模式
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
.permitAll().build();
StrictMode.setThreadPolicy(policy);
}
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() {
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);
}
}
}
});
new Thread(SocketDemo.this).start();
}
public void ShowDialog(String msg) {
new AlertDialog.Builder(this).setTitle("notification").setMessage(msg)
.setPositiveButton("ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
}).show();
}
public void run() {
try {
while (true) {
if (socket.isConnected()) {
if (!socket.isInputShutdown()) {
if ((content = in.readLine()) != null) {
content += "
";
mHandler.sendMessage(mHandler.obtainMessage());
} else {
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public Handler mHandler = new Handler() {
public void handleMessage(Message msg) {
super.handleMessage(msg);
tv_msg.setText(tv_msg.getText().toString() + content);
}
};
}
下面是服务器端的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("server start ...");
Socket client = null;
while(true) {
client = server.accept();
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()));
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) {
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;
} 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
<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