I'm basically using Eclipse. Actually it's SpringSource Tool Suite, which is Eclipse Indigo with Spring plugins.
Anyway, no matter. Yes, with Java 1.6 you need to close the streams and sockets to flush the output to the browser. That's what it expects. The Java 1.7 construct automatically closes the streams and socket however the block ends.
Apart from playing with Java 1.7 this morning, I also had a quick play with Apache Velocity again and I think it would be useful. Writing out HTML using println statements gets messy after a while.
http://www.javaworld.com/javaworld/jw-12-2001/jw-1228-velocity.html
http://velocity.apache.org/engine/devel/index.html
Luckily for this particular application, very little needs to be returned from the daemon back to the web layer. Just some acknowledgement that it received the command and that it processed correctly, so sending back complicated HTML is not an issue here.
I am having an issue when I try to connect using jquery though.
Here's my code:
AdminListener.java (very little changed here from the previous post)
package com.mypackage;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
public class AdminListener extends Thread
{
// You'd need to check that nothing else is listening on this
// arbitrary port number, e.g. netstat -ln | grep 12345
private static final int PORT = 12345;
// The data collector is running as the main thread. This
// reference allows us to access its properties.
private DataCollector dataCollector;
public AdminListener(DataCollector dataCollector)
{
this.dataCollector = dataCollector;
}
public void run()
{
// The new try-with-resources block in Java 1.7 automatically
// closes the resource that it opened :)
try
{
ServerSocket serverSocket = new ServerSocket(PORT);
while (true)
{
acceptConnections(serverSocket);
}
}
catch (IOException e)
{
System.err.println("Failed to start listener");
}
}
private void acceptConnections(ServerSocket serverSocket) throws IOException
{
Socket socket = null;
try
{
socket = serverSocket.accept();
// If I wanted a multi-threaded server I would have to spawn
// another thread to deal with the request and go straight back
// to accepting connections. But this is single-threaded, i.e.
// it only allows one connection to the admin listener.
InetAddress client = socket.getInetAddress();
System.out.println("Received request from " + client.getHostAddress());
BufferedReader in = null;
PrintWriter out = null;
try
{
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
try
{
out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
doResponse(in, out);
}
catch (Exception e)
{
e.printStackTrace();
}
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
in.close();
in = null;
out.close();
out = null;
}
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
socket.close();
socket = null;
}
}
private void doResponse(BufferedReader in, PrintWriter out) throws IOException
{
System.out.println("Accepted request");
String request = in.readLine();
if (request != null)
{
// Send out the HTTP response line and headers to make the browser happy
out.println("HTTP/1.1 200 OK");
out.println("Content-Type: text/html");
out.println(); // Blank line to separate header and content
out.println("<html><head><title>Admin</title></head><body>");
out.printf("<h1>%s</h1>", request);
// This represents getting data from the collector.
out.println("<p><b>System information:</b></p>");
out.println("<span style=\"color: #800000\"><ul>");
out.printf("<li>%s</li>", dataCollector.getProperties().get("java.version"));
out.printf("<li>%s</li>", dataCollector.getProperties().get("java.vendor"));
out.println("</ul></span>");
out.println("</body>");
out.flush();
}
else
{
out.println("HTTP/1.1 200 OK");
out.println("Content-Type: text/html");
out.println(); // Blank line to separate header and content
out.println("<html><head><title>Admin</title></head><body>");
out.printf("<h1>%s</h1>", request);
// This represents getting data from the collector.
out.println("<p><b>System information:</b></p>");
out.println("<span style=\"color: #800000\"><ul>");
out.println("No arguments");
out.println("</ul></span>");
out.println("</body>");
out.flush();
}
System.out.println("Finished request");
}
}
index.html
<html>
<head>
<title>Test Interface</title>
</head>
<body>
Data: <input type="text" name="data_name" id="data_id" /><br />
<input type="submit" id="submit" value="Submit" /><br />
<div id="processing">Processing!</div><br><br>
<div id="results" style="border: 1px solid black; min-height: 100px"></div>
<script type="text/javascript" src="jquery-1.7.1.js"></script>
<script type="text/javascript" src="ajaxSubmit.js"></script>
</body>
</html>
ajaxSubmit.js
$(document).ready(function(){
$('#processing').hide(0);
$('#submit').click(function() {
$('#processing').fadeTo(500, 1.0);
$.ajax({
type: "POST",
url: "http://localhost:12345/someCommand"
}).done(function( msg ) {
alert("Returned");
});
return false;
});
});
When I click the submit button, the Processing div fades in as expected, the ajax call fires off, the server receives it (I see it in the console output from the daemon), but the done() function is never called. When I run it through firebug on FFX, it sees that the POST call was made, says 200 OK, and the line is in red. When I open it up for more details, the headers look correct, but there isn't anything under the HTML tab.
There are a couple of notes I'd like to make since I'm sure someone will wonder:
No, this is not for a class.
No, I'm not doing fully fleshed out Java right now (like closing the streams in a safe way), I'm just trying to get a proof of concept working.