对于程序开发来说,网络通信的基础就是Socket,但因为是基础,所以用起来不容易,今天我们就来谈谈Socket通信。计算机网络有个大名鼎鼎的TCP/IP协议,普通用户在电脑上设置本地连接的ip时,便经常看到下图的弹窗,注意红框部分已经很好地描述了TCP/IP协议的作用。
TCP/IP是个协议组,它分为三个层次:网络层、传输层和应用层: 网络层包括:IP协议、ICMP协议、ARP协议、RARP协议和BOOTP协议。 传输层包括:TCP协议、UDP协议。 应用层包括:HTTP、FTP、TELNET、SMTP、DNS等协议。 之前我们提到的网络编程,其实都是应用层方面的http或ftp编程;而socket属于传输层的技术,它的api实现TCP协议后即可用于http通信,实现UDP协议后即可用于ftp通信,当然也可以直接在底层进行点对点通信,比如即时通信软件(QQ、微信)这样就是。 扯远了,言归正传,java的socket编程主要使用Socket和ServerSocket两个类,下面是相关类的使用说明。
Socket是最常用的,客户端和服务端都要用到,它描述了两边对套接字(即Socket)处理的一般行为,主要方法说明如下: connect : 连接指定ip和端口。该方法用于客户端连接服务端。 getInputStream : 获取输入流。即自己收到对方发过来的数据。 getOutputStream : 获取输入流。即自己向对方发送的数据。 getInetAddress : 获取网络地址对象。该对象是一个InetAddress实例。 isConnected : 判断socket是否连上。 isClosed : 判断socket是否关闭。 close : 关闭socket。
ServerSocket仅用于服务端,它在运行时不停地侦听指定端口,主要方法说明如下: 构造函数 : 指定侦听哪个端口。 accept : 开始接收客户端的连接。有客户端连上时就返回一个Socket对象,若要持续侦听连接,得在循环中调用该函数。 getInetAddress : 获取网络地址对象。该对象是一个InetAddress实例。 isClosed : 判断socket服务器是否关闭。 close : 关闭socket服务器。
InetAddress是对网络地址的一个封装,主要方法说明如下: getByName : 根据主机ip/名称获取InetAddress对象。 getHostAddress : 获取主机的ip地址。 getHostName : 获取主机的名称。 isReachable : 判断该地址是否可到达,即是否连通。
Socket在app开发中主要用于聊天/即时通信,因为涉及到客户端与服务端的交互,所以流程稍微复杂。首先要划分聊天业务的功能点,以QQ为例,我们平常看到的是三种页面:登录页面、好友列表页面、聊天页面。因此,对应的Socket功能也分为三类: 登录/注销:登录操作对应建立Socket连接,而注销操作对应断开Socket连接。 获取好友列表:与Socket有关的是获取当前在线的好友列表,客户端到服务端查询当前已建立Socket连接的好友列表。 发送消息/接收消息:发送/接收消息对应的是Socket的数据传输,发送消息操作是客户端A向服务端发送Socket数据,接收消息操作是服务端将收到的A消息向客户端B发送Socket数据。 其次在app端需要实现以下功能: 1、至少三个页面:登录页面、好友列表页面、聊天页面; 2、一个用于Socket通信的线程。由于在app运行过程中都要保持Socket连接,因此该Socket线程要放在自定义的Application类中。 3、页面向Socket线程发送消息的机制,用于登录请求、注销请求、获取好友列表请求、发送消息等等。主线程与子线程通信,我们这里采用Handler+Message机制来处理,有关该机制的使用说明参见《Android开发笔记(四十八)Thread类实现多线程》。 4、Socket线程向页面发送消息的机制,用于返回好友列表、接收消息等等。因为返回消息会分发到不同的页面,采用Handler机制有困难,所以这里我们采用Broadcast广播来处理,在好友列表页面和聊天页面各注册一个广播接收器,用于根据服务器返回数据刷新UI。有关Broadcast及其接收器的使用说明参见《Android开发笔记(四十二)Broadcast的生命周期》。 然后在服务端启动Socket服务器,要实现的功能有: 1、定义一个Socket连接的队列,用于保存当前连上的Socket请求; 2、循环侦听指定端口,一旦有新连接进来,则将该连接加入Socket队列,并启动新线程为该连接服务; 3、每个服务线程持续从Socket中读取客户端发过来的数据,并对不同请求做相应的处理: a、如果是登录请求,则标识该Socket连接的用户昵称、设备编号、登录时间等信息; b、如果是注销请求,则断开Socket连接,并从Socket队列中移除该连接; c、如果是获取好友列表请求,则遍历Socket队列,封装好友列表数据并返回; d、如果是发送消息请求,则根据好友的设备编号到Socket队列中查找对应的Socket连接,并向该连接返回消息内容; 最后还要定义一下服务端与客户端之间传输消息的格式,按惯例消息包分为包头与包体两块,包头用于标识操作类型、操作对象、操作时间等基本要素,而包体用于存放具体的消息内容(如好友列表、消息文本等等)。demo工程为简单起见,就不用xml或json等标准格式,直接用分隔符划分包头与包体,以及包头内部的各元素。
博主在测试时,模拟器上开了一个app,登录名称是“在水一方”,真机上开了一个app,登录名称是“振兴中华”,两个app连的都是电脑上的Socket服务,从而模拟真实的聊天室环境。登录页面与好友列表页面比较简单,就不再截图了,截的都是聊天窗口页面。为了做得更逼真,中间消息窗口采用对方消息靠左对齐,我方消息靠右对齐的布局,并给双方消息着不同的背景色。具体截图如下,左侧图片是真机截图,右侧图片是模拟器截图。
几个注意点: 1、自定义Application类需要采用单例模式,确保Socket线程的唯一性,详细原因参见《Android开发笔记(八十九)单例模式》。 2、Socket数据包不可直接用换行符“\n”做分隔符,因为在Socket通信中,换行符表示该数据包结束了,所以加了一个换行符,原来一个数据包就变成了两个数据包。正因如此,用户聊天的消息文本中若有换行符,则要先进行转义后才能发给Socket传输。 3、如果广播接收器在代码中动态注册,则不会收到Socket线程发出的广播消息;只有在AndroidManifest.xml中对接收器做静态注册,才能收到Socket线程发出的广播消息,具体原因不明,可能与线程有关。 下面是自定义Application类的代码:
import com.example.exmsocket.thread.ClientThread;
import com.example.exmsocket.util.DateUtil;
import android.app.Application;
import android.os.Build;
import android.os.Message;
import android.util.Log;
public class MainApplication extends Application {
private static final String TAG = "MainApplication";
private static MainApplication mApp;
private String mNickName;
private ClientThread mClientThread;
public static MainApplication getInstance() {
return mApp;
}
@Override
public void onCreate() {
super.onCreate();
mApp = this;
mClientThread = new ClientThread(mApp);
new Thread(mClientThread).start();
}
public void sendAction(String action, String otherId, String msgText) {
String content = String.format("%s,%s,%s,%s,%s%s%s\r\n",
action, Build.SERIAL, getNickName(), DateUtil.getNowTime(),
otherId, ClientThread.SPLIT_LINE, msgText);
Log.d(TAG, "sendAction : " + content);
Message msg = Message.obtain();
msg.obj = content;
if (mClientThread==null || mClientThread.mRecvHandler==null) {
Log.d(TAG, "mClientThread or its mRecvHandler is null");
} else {
mClientThread.mRecvHandler.sendMessage(msg);
}
}
public void setNickName(String nickName) {
mApp.mNickName = nickName;
}
public String getNickName() {
return mApp.mNickName;
}
}
下面是登录页面的代码:
import com.example.exmsocket.thread.ClientThread;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity implements OnClickListener {
private static final String TAG = "MainActivity";
private EditText et_name;
private Button btn_ok;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_name = (EditText) findViewById(R.id.et_name);
btn_ok = (Button) findViewById(R.id.btn_ok);
btn_ok.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.btn_ok) {
String nickName = et_name.getText().toString().trim();
if (nickName.length() <= 0) {
Toast.makeText(this, "请输入您的昵称", Toast.LENGTH_SHORT).show();
} else {
MainApplication.getInstance().setNickName(nickName);
MainApplication.getInstance().sendAction(ClientThread.LOGIN, "", "");
Intent intent = new Intent(this, FriendListActivity.class);
startActivity(intent);
finish();
}
}
}
}
下面是好友列表页面的代码:
import java.util.ArrayList;
import com.example.exmsocket.adapter.Friend;
import com.example.exmsocket.adapter.FriendListAdapter;
import com.example.exmsocket.thread.ClientThread;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
public class FriendListActivity extends Activity implements OnClickListener {
private static final String TAG = "FriendListActivity";
private static Context mContext;
private static ListView lv_friend;
private Button btn_refresh;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
mContext = getApplicationContext();
lv_friend = (ListView) findViewById(R.id.lv_friend);
btn_refresh = (Button) findViewById(R.id.btn_refresh);
btn_refresh.setOnClickListener(this);
}
@Override
protected void onResume() {
mHandler.postDelayed(mRefresh, 500);
super.onResume();
}
@Override
protected void onDestroy() {
MainApplication.getInstance().sendAction(ClientThread.LOGOUT, "", "");
super.onDestroy();
}
private Handler mHandler = new Handler();
private Runnable mRefresh = new Runnable() {
@Override
public void run() {
MainApplication.getInstance().sendAction(ClientThread.GETLIST, "", "");
}
};
@Override
public void onClick(View v) {
if (v.getId() == R.id.btn_refresh) {
mHandler.post(mRefresh);
}
}
public static class GetListReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if (intent != null) {
Log.d(TAG, "onReceive");
String content = intent.getStringExtra(ClientThread.CONTENT);
if (mContext != null && content != null && content.length() > 0) {
int pos = content.indexOf(ClientThread.SPLIT_LINE);
String head = content.substring(0, pos);
String body = content.substring(pos + 1);
String[] splitArray = head.split(ClientThread.SPLIT_ITEM);
if (splitArray[0].equals(ClientThread.GETLIST)) {
String[] bodyArray = body.split("\\|");
ArrayList<Friend> friendList = new ArrayList<Friend>();
for (int i = 0; i < bodyArray.length; i++) {
String[] itemArray = bodyArray[i].split(ClientThread.SPLIT_ITEM);
if (bodyArray[i].length() > 0 && itemArray != null && itemArray.length >= 3) {
friendList.add(new Friend(itemArray[0], itemArray[1], itemArray[2]));
}
}
if (friendList.size() > 0) {
FriendListAdapter adapter = new FriendListAdapter(mContext, friendList);
lv_friend.setAdapter(adapter);
lv_friend.setOnItemClickListener(adapter);
}
} else {
String hint = String.format("%s\n%s", splitArray[0], body);
Toast.makeText(mContext, hint, Toast.LENGTH_SHORT).show();
}
}
}
}
}
}
下面是聊天页面的代码:
import com.example.exmsocket.thread.ClientThread;
import com.example.exmsocket.util.DateUtil;
import com.example.exmsocket.util.MetricsUtil;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
public class ChatActivity extends Activity implements OnClickListener {
private static final String TAG = "ChatActivity";
private static Context mContext;
private TextView tv_other;
private EditText et_input;
private static TextView tv_show;
private static LinearLayout ll_show;
private Button btn_send;
private String mOtherId;
private static int dip_margin;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
mContext = getApplicationContext();
tv_other = (TextView) findViewById(R.id.tv_other);
et_input = (EditText) findViewById(R.id.et_input);
tv_show = (TextView) findViewById(R.id.tv_show);
ll_show = (LinearLayout) findViewById(R.id.ll_show);
btn_send = (Button) findViewById(R.id.btn_send);
btn_send.setOnClickListener(this);
dip_margin = MetricsUtil.dip2px(mContext, 5);
Bundle bundle = getIntent().getExtras();
mOtherId = bundle.getString("otherId", "");
String desc = String.format("与%s聊天", bundle.getString("otherName", ""));
tv_other.setText(desc);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.btn_send) {
String body = et_input.getText().toString();
String append = String.format("%s %s\n%s",
MainApplication.getInstance().getNickName(),
DateUtil.formatTime(DateUtil.getNowTime()), body);
appendMsg(Build.SERIAL, append);
MainApplication.getInstance().sendAction(ClientThread.SENDMSG, mOtherId, body);
et_input.setText("");
}
}
private static void appendMsg(String deviceId, String append) {
//tv_show.setText(tv_show.getText().toString() + append);
int gravity = deviceId.equals(Build.SERIAL) ? Gravity.RIGHT : Gravity.LEFT;
int bg_color = deviceId.equals(Build.SERIAL) ? 0xffccccff : 0xffffcccc;
LinearLayout ll_append = new LinearLayout(mContext);
LinearLayout.LayoutParams ll_params = new LinearLayout.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
ll_params.setMargins(dip_margin, dip_margin, dip_margin, dip_margin);
ll_append.setLayoutParams(ll_params);
ll_append.setGravity(gravity);
TextView tv_append = new TextView(mContext);
tv_append.setText(tv_show.getText().toString() + append);
tv_append.setTextColor(Color.BLACK);
LinearLayout.LayoutParams tv_params = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
tv_append.setLayoutParams(tv_params);
tv_append.setBackgroundColor(bg_color);
ll_append.addView(tv_append);
ll_show.addView(ll_append);
}
public static class RecvMsgReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if (intent != null) {
Log.d(TAG, "onReceive");
String content = intent.getStringExtra(ClientThread.CONTENT);
if (mContext != null && content != null && content.length() > 0) {
int pos = content.indexOf(ClientThread.SPLIT_LINE);
String head = content.substring(0, pos);
String body = content.substring(pos + 1);
String[] splitArray = head.split(ClientThread.SPLIT_ITEM);
if (splitArray[0].equals(ClientThread.RECVMSG)) {
String append = String.format("%s %s\n%s",
splitArray[2], DateUtil.formatTime(splitArray[3]), body);
appendMsg(splitArray[1], append);
} else {
String hint = String.format("%s\n%s", splitArray[0], body);
Toast.makeText(mContext, hint, Toast.LENGTH_SHORT).show();
}
}
}
}
}
}
下面是Socket线程的代码:
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
import android.content.Context;
import android.content.Intent;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
public class ClientThread implements Runnable {
private static final String TAG = "ClientThread";
private static final String SOCKET_IP = "192.168.0.212"; // 模拟器使用
//private static final String SOCKET_IP = "192.168.253.1"; // 真机使用
private static final int SOCKET_PORT = 52000;
public static String ACTION_RECV_MSG = "com.example.exmsocket.RECV_MSG";
public static String ACTION_GET_LIST = "com.example.exmsocket.GET_LIST";
public static String CONTENT = "CONTENT";
public static String SPLIT_LINE = "|";
public static String SPLIT_ITEM = ",";
public static String LOGIN = "LOGIN";
public static String LOGOUT = "LOGOUT";
public static String SENDMSG = "SENDMSG";
public static String RECVMSG = "RECVMSG";
public static String GETLIST = "GETLIST";
private Context mContext;
private Socket mSocket;
// 定义接收UI线程的Handler对象
public Handler mRecvHandler;
private BufferedReader mReader = null;
private OutputStream mWriter = null;
public ClientThread(Context context) {
mContext = context;
}
@Override
public void run() {
mSocket = new Socket();
try {
mSocket.connect(new InetSocketAddress(SOCKET_IP, SOCKET_PORT), 3000);
mReader = new BufferedReader(new InputStreamReader(mSocket.getInputStream()));
mWriter = mSocket.getOutputStream();
// 启动一条子线程来读取服务器相应的数据
new Thread() {
@Override
public void run() {
String content = null;
try {
while ((content = mReader.readLine()) != null) {
// 读取到来自服务器的数据之后,发送消息通知
ClientThread.this.notify(0, content);
}
} catch (Exception e) {
e.printStackTrace();
ClientThread.this.notify(97, e.getMessage());
}
}
}.start();
Looper.prepare();
mRecvHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
// 接收到UI线程的中用户输入的数据
try {
mWriter.write(msg.obj.toString().getBytes("utf8"));
} catch (Exception e) {
e.printStackTrace();
ClientThread.this.notify(98, e.getMessage());
}
}
};
Looper.loop();
} catch (Exception e) {
e.printStackTrace();
notify(99, e.getMessage());
}
}
private void notify(int type, String message) {
if (type == 99) {
String content = String.format("%s%s%s%s", "ERROR", SPLIT_ITEM, SPLIT_LINE, message);
Intent intent1 = new Intent(ACTION_RECV_MSG);
intent1.putExtra(CONTENT, content);
mContext.sendBroadcast(intent1);
Intent intent2 = new Intent(ACTION_GET_LIST);
intent2.putExtra(CONTENT, content);
mContext.sendBroadcast(intent2);
} else {
int pos = message.indexOf(SPLIT_LINE);
String head = message.substring(0, pos-1);
String[] splitArray = head.split(SPLIT_ITEM);
String action = "";
if (splitArray[0].equals(RECVMSG)) {
action = ACTION_RECV_MSG;
} else if (splitArray[0].equals(GETLIST)) {
action = ACTION_GET_LIST;
}
Log.d(TAG, "action="+action+", message="+message);
Intent intent = new Intent(action);
intent.putExtra(CONTENT, message);
mContext.sendBroadcast(intent);
}
}
}
下面是服务端的主程序代码:
import java.net.ServerSocket;
import java.util.ArrayList;
public class ChatServer {
private static final int SOCKET_PORT = 52000;
public static ArrayList<SocketBean> mSocketList = new ArrayList<SocketBean>();
private void initServer() {
try {
// 创建一个ServerSocket,用于监听客户端Socket的连接请求
ServerSocket server = new ServerSocket(SOCKET_PORT);
while (true) {
// 每当接收到客户端的Socket请求,服务器端也相应的创建一个Socket
SocketBean socket = new SocketBean(DateUtil.getTimeId(), server.accept());
mSocketList.add(socket);
// 每连接一个客户端,启动一个ServerThread线程为该客户端服务
new Thread(new ServerThread(socket)).start();
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
ChatServer server = new ChatServer();
server.initServer();
}
}
下面是服务线程的代码:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
public class ServerThread implements Runnable {
private SocketBean mSocket = null;
private BufferedReader mReader = null;
public ServerThread(SocketBean mSocket) throws IOException {
this.mSocket = mSocket;
mReader = new BufferedReader(new InputStreamReader(
mSocket.socket.getInputStream()));
}
@Override
public void run() {
try {
String content = null;
// 循环不断地从Socket中读取客户端发送过来的数据
while ((content = mReader.readLine()) != null) {
System.out.println("content="+content);
int pos = content.indexOf("|");
// 包头格式为:动作名称|设备编号|昵称|时间|对方设备编号
String head = content.substring(0, pos);
String body = content.substring(pos+1);
String[] splitArray = head.split(",");
String action = splitArray[0];
System.out.println("action="+action);
if (action.equals("LOGIN")) {
login(splitArray[1], splitArray[2], splitArray[3]);
} else if (action.equals("LOGOUT")) {
logout(splitArray[1]);
break;
} else if (action.equals("SENDMSG")) {
sendmsg(splitArray[2], splitArray[4], splitArray[1], body);
} else if (action.equals("GETLIST")) {
getlist(splitArray[1]);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
private void login(String deviceId, String nickName, String loginTime) throws IOException {
for (int i=0; i<ChatServer.mSocketList.size(); i++) {
SocketBean item = ChatServer.mSocketList.get(i);
if (item.id.equals(mSocket.id)) {
item.deviceId = deviceId;
item.nickName = nickName;
item.loginTime = loginTime;
ChatServer.mSocketList.set(i, item);
break;
}
}
}
private String getFriend() {
String friends = "GETLIST,";
for (SocketBean item : ChatServer.mSocketList) {
if (item.deviceId!=null && item.deviceId.length()>0) {
String friend = String.format("|%s,%s,%s", item.deviceId, item.nickName, item.loginTime);
friends += friend;
}
}
return friends;
}
private void getlist(String deviceId) throws IOException {
for (int i=0; i<ChatServer.mSocketList.size(); i++) {
SocketBean item = ChatServer.mSocketList.get(i);
if (item.id.equals(mSocket.id) && item.deviceId.equals(deviceId)) {
PrintStream printStream = new PrintStream(item.socket.getOutputStream());
printStream.println(getFriend());
break;
}
}
}
private void logout(String deviceId) throws IOException {
for (int i=0; i<ChatServer.mSocketList.size(); i++) {
SocketBean item = ChatServer.mSocketList.get(i);
if (item.id.equals(mSocket.id) && item.deviceId.equals(deviceId)) {
PrintStream printStream = new PrintStream(item.socket.getOutputStream());
printStream.println("LOGOUT,|");
item.socket.close();
ChatServer.mSocketList.remove(i);
break;
}
}
}
private void sendmsg(String otherName, String otherId, String selfId, String message) throws IOException {
for (int i=0; i<ChatServer.mSocketList.size(); i++) {
SocketBean item = ChatServer.mSocketList.get(i);
if (item.deviceId.equals(otherId)) {
String content = String.format("%s,%s,%s,%s|%s",
"RECVMSG", selfId, otherName, DateUtil.getNowTime(), message);
PrintStream printStream = new PrintStream(item.socket.getOutputStream());
printStream.println(content);
break;
}
}
}
}