我正在创建一个Android客户端,我想确保它可以连接到Java服务器。
我的服务器是这个
public static void main(String[] args){
int portNumber = 5885;
System.out.println("Starting..");
// We use a try-with-resources statement to ensure that all sockets and
// readers/writers are closed when the program terminates
try (
// Set up the server socket on a specified port number
ServerSocket serverSocket = new ServerSocket(portNumber);
// Wait until a connection is made by a client and accept its socket
Socket clientSocket = serverSocket.accept();
// Set up a writer to the client socket
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
// Set up a reader from the client socket
BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
) {
// Missing Part
} catch (IOException e) {
System.out.println("Exception caught when trying to listen on port " + portNumber + " or listening for a connection");
System.out.println(e.getMessage());
}
}
}
并且客户端正在尝试与此代码连接
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.board_layout);
new Thread(new ClientThread()).start();
}
class ClientThread implements Runnable {
@Override
public void run() {
try {
InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
socket = new Socket(serverAddr, SERVERPORT);
} catch (UnknownHostException e1) {
e1.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
我如何检查是否有人连接到服务器?与
if (clientSocket != null)
System.out.println("Someone is in");
或者其他的东西?
最佳答案
如果您想知道客户端是否已连接,serverSocket.accept()
将阻止,直到有人连接为止。这也应处于为每个客户端生成专用线程的循环中。
如果要可靠地确认客户端已连接,我将使用心跳信号(来自客户端的消息的全部目的是确认连接状态):
使每个客户端将心跳发送到服务器。例如,在客户端有一个线程休眠一段时间(10秒),然后醒来发送心跳。这样,如果您在一段时间内未收到心跳,则说明存在连接问题。
只是为了说明这个概念:
服务器:
public void startServer() throws IOException{
ServerSocket serverSocket = new ServerSocket(9209);
List<ClientThread> clientThreads = new ArrayList<ClientThread>();
boolean running = true;
while(running){
try {
Socket clientSocket = serverSocket.accept();
ClientThread clientThread = new ClientThread(clientSocket);
clientThread.run();
clientThreads.add(clientThread);
} catch (IOException e) {
e.printStackTrace();
}
}
for(ClientThread thread : clientThreads){
thread.shutdown();
}
}
public class ClientThread extends Thread{
private BufferedReader in;
private volatile boolean running = true;
private long lastHeartBeat;
public ClientThread(Socket socket) throws IOException{
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
}
public void shutdown(){
running = false;
}
@Override
public void run() {
while(running){
try {
if(in.readLine().equalsIgnoreCase("HeartBeat")){
lastHeartBeat = System.currentTimeMillis();
}else{
//do something else
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
每个客户端创建以下之一:
public class HeartBeatThread extends Thread{
PrintWriter out;
volatile boolean running = true;
public HeartBeatThread(Socket socket) throws IOException{
this.out = new PrintWriter(socket.getOutputStream(), true);
}
public void shutdown(){
running = false;
}
@Override
public void run() {
while(running){
try {
sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
out.println("HeartBeat");
}
}
}
关于java - 我如何测试有人已连接到我的服务器?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/23583637/