Here I am creating a thread to check for a server response every 2 seconds, the issue is that the client.monitorResponse()
is a readLine()
method and will not continue until a response is received.
client = new ClientObject("localhost");
timer.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
try {
String response = null;
if(!(response = client.monitorResponse()).isEmpty()) {
System.out.println("Response: " + response);
} catch (Exception e) {
e.printStackTrace();
}
}
}, 2000, 2000);
I am sending the response via the Server like so (where client
is a established Socket):
public SocketObject(Socket client, int numberOfClients) throws Exception {
socket = client; // the .accept() socket is passed through
// this is because I assign them ID's for later use (I hold an ArrayList of sockets)
this.clientId = numberOfClients;
// both these are static to the class
outputStream = new PrintWriter(client.getOutputStream());
inputStream = new BufferedReader(new InputStreamReader(client.getInputStream()));
}
public void sendResponse(String response) {
outputStream.println(response);
}
I am then picking the response up via the client Socket that has connected to the server:
public ClientObject(String hostname) throws IOException {
// socket is static to this class
socket = new Socket(hostname, 4444);
System.out.println("Connected to " + hostname + " on port 4444...");
// both static to this class
outputStream = new PrintWriter(socket.getOutputStream(), true);
inputStream = new BufferedReader(new InputStreamReader(socket.getInputStream()));
System.out.println("Successfully started a stream on " + hostname);
this.hostname = hostname;
}
public String monitorResponse() throws Exception {
System.out.println("Listening for a response...");
return inputStream.readLine();
}
The debug console only displays the Listening for a response... output once which is telling me that it doesn't get past the inputStream.readLine()
method in-side the Thread. Is there anyway I can add a timeout on the BufferedReader? I have tried multiple solutions like adding a .setSoTimeout()
to the socket before creating the BufferedReader but all that did was close the connection/socket after the specified time.
Any help would be appreciated.
You should use a non-blocking (NIO) request and read chunks looking for newlines in-between. Typically in Java you just have to look for the NIO version of the Stream class you are using and use it to check every N seconds for new content. In your case with minimal modifications you can use the less fancy and efficient method of blocking calls with BufferedReader.ready()
to prevent blocking:
String partialLine="";
public static String monitorResponse() throws Exception {
System.out.println("Listening for a response...");
int nextByte;
String nextChar;
while (inputStream.ready()) {
nextByte = inputStream.read();
nextChar = Character.toString ((char) nextByte);
partialLine += nextChar;
if ("\n".equals(nextChar)) {
String line = partialLine;
partialLine = "";
return line.replace("\r\n", "");
}
}
return "";
}
Check out http://tutorials.jenkov.com/java-nio/nio-vs-io.html for more info.
Is there anyway I can add a timeout on the BufferedReader?
No, but you can set a timeout on the Socket
, with Socket.setSoTimeout()
.
I have tried multiple solutions like adding a .setSoTimeout() to the socket before creating the BufferedReader but all that did was close the connection/socket after the specified time.
No it doesn't close the socket. It throws SocketTimeoutException
, which you should catch and handle as pertinent. If the socket is being closed, you're closing it. Solution: don't.
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