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Send data from php to java

I have found quite a lot of other posts on this topic but none seem to have the answer I need.
I have written a Bukkit plugin for Minecraft that can send post data to a PHP page and get a return from the page.
Now the one thing I can't figure out. I would like to have a button on the page, and when the button is clicked, send data to the Java plugin and have the plugin print the message.
I have seen something about sockets. But after reading about them I can't figure out how to set them up.
Pretty much at any time you should be able to click the button and it sends data to the Java plugin and I can use that data however I like.
Does anyone know how I can have the Java plugin constantly waiting for data from the page?
My current code:
(This sends the players name to the website.)
String re = "";
URL url = new URL("address here");
URLConnection con = url.openConnection();
con.setDoOutput(true);
PrintStream ps = new PrintStream(con.getOutputStream());
ps.print("player=" + player.getName());
con.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(con.getInputStream()));
String line;
while ((line = rd.readLine()) != null) {
re += line + "\n";
}
rd.close();
ps.close();
And my php just returns any post data it gets.
It works fine, but I would like to listen in my java plugin for data from the php page.

There are many ways to make communication between two servers. I'd use one of them:
Sockets
JMS - Java Message Service such as ActiveMQ
Both of them have tutorials available, just google.

You could use a database, or setup a json/xml api on the PHP end, and access the database, or access the json/xml from Java with this example code to open the url.
URL url = new URL("site.com/api/foo.json");
try (BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"))) {
for (String line; (line = reader.readLine()) != null;) {
System.out.println(line);
}
}
You can look at this tutorial to parse JSON with Java.

Can't access server socket with android app

I want to see the exact headers my android app is sending while making a web request so I thought I'd simply create a simple server app in java on my local machine and have my android app make a call to it. Then simply dump the request to the console so I could see what the app is sending. However when I tried to connect, the app hangs and stops responding.
I created a simple server the only accepts a connection and sysouts the data it gets. The server runs fine and if I hit it from a web browser on my computer will print the headers from the web browsers request. So I know the server works fine.
Here's the code from my app:
URL url = new URL("http://192.168.1.11:9000");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.connect();
PrintWriter writer = new PrintWriter(connection.getOuputStream(), true);
writer.write("hi");
writer.close();
Simple. I only want the headers after all. Now I started without a post and using:
URL url = new URL("http://192.168.1.11:9000");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
in.close();
but that doesn't work. The app stops responding on the getInputStream() request. It just stops and won't continue. The server gets no connection request either.
So in all, the app is blocking on the url connection's getInputStream and I can't figure out why.
Now I've searched for awhile and found these:
Android app communicating with server via sockets
socket exception socket not connected android
Android embedded browser cant connect to server on LAN
Using java.net.URLConnection to fire and handle HTTP requests
Client Socket cannot connect to running Socket server
But nothing helps. I'm not using the localhost like everyone with this problem seems to be and I've tried using the androids 10.0.0.2 but that doesnt work either.
I'm not on a network that restricts anything (I'm home) and I've tried using the first set of code shown in order to send a message to my server but not even that works (it runs fine but the server never gets a client. Hows that work?).
I tried using both URLConnection and HttpURLConnection, they both have the same problem.
I'm also using the internet permission in my app, so it does have the permission needed.
I'm at a loss at this point. Why can't I make a simple call to my server?
EDIT
I used the exact code from androids documentation:
private String downloadUrl(String myurl) throws IOException {
InputStream is = null;
// Only display the first 500 characters of the retrieved
// web page content.
int len = 500;
try {
URL url = new URL("http://10.0.2.2:9000");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("GET");
conn.setDoInput(true);
// Starts the query
conn.connect();
int response = conn.getResponseCode();
is = conn.getInputStream();
// Convert the InputStream into a string
String contentAsString = readIt(is, len);
return contentAsString;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} finally {
if (is != null) {
is.close();
}
}
}
but even that doesn't work. It still hangs. Only now it hangs on the getResponseCode(). Then throws a timeout exception. The server never gets a request though.

Your address must start with 'http://", try again!

I think the root of your issue is that Android is FCing your app before the connection completes, because I assume you haven't wrapped this in a Loader, AsyncTask or Thread. I suggest you follow the training guide Google provides, wrapping your call in an AsyncTask and seeing if that corrects the issue.

I have a Java class I use for making HTTP GET requests, I'm guessing its near identical to the android code your using so below I've dumped the relevant part of the code. I've used this class many times in Java applications (not on Android).
currentUrl = new URL(getUrl);
conn = (HttpURLConnection)currentUrl.openConnection();
conn.setRequestProperty("Cookie", getCookies(currentUrl.getHost()));
conn.setRequestProperty("User-Agent", "robadob.org/crawler");
if(referrer!=null){conn.setRequestProperty("Referrer",referrer);}
conn.setRequestMethod("GET");
conn.connect();
//Get response
String returnPage = "";
String line;
BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = rd.readLine()) != null) {
returnPage+=line+"\n";
}
rd.close();
I can't see anything obvious that would be causing your code to fail, but hopefully you can spot something from this. The setRequestProperty is me setting headers, so you shouldn't need those.
If that fails, flood your code with System.out's so you can see which statement its stalling at.

Taking text from a response web page using Java

I am sending commands to a server using http, and I currently need to parse a response that the server sends back (I am sending the command via the command line, and the servers response appears in my browser).
There are a lot of resources such as this: Saving a web page to a file in Java, that clearly illustrate how to scrape a page such as cnn.com. However, since this is a response page that is only generated when the camera receives a specific command, my attempts to use the method described by Mike Deck (in the link above) have met with failure. (Specifically, when my program requests the page again the server returns a 401 error.)
The response from the server opens a new tab in my browser. Essentially, I need to know how to save the current web page using java, since reading in a file is probably the most simple way to approach this. Do any of you know how to do this?
TL;DR How do you save the current webpage to a webpage.html or webpage.txt file using java?
EDIT: I used Base64 from the Apache commons codec, which solved my 401 authentication issue. However, I am still getting a 400 error when I attempt to connect my InputStream (see below). Does this mean a connection isn't being established in the first place?
URL url = new URL ("http://"+ipAddress+"/axis-cgi/record/record.cgi?diskid=SD_DISK");
byte[] encodedBytes = Base64.encodeBase64("root:pass".getBytes());
String encoding = new String (encodedBytes);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoInput (true);
connection.setRequestProperty ("Authorization", "Basic " + encoding);
connection.connect();
InputStream content = (InputStream)connection.getInputStream();
BufferedReader in = new BufferedReader (new InputStreamReader (content));
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
EDIT 2: Changing the request to a GET resolved the issue.

So while scrutinizing my code above, I decided to change
connection.setRequestMethod("POST");
to
connection.setRequestMethod("GET");
This solved my problem. In hindsight, I think the server was not recognizing the HTTP because it is not set up to handle the various trappings that come along with post.

HttpURLConnection returns 503 error when accessed through proxy

I am working on creating a Video sitemap for a site that has hosted videos on Brightcove video cloud. In order to get all the video information from the site, Brightcove suggests to read the response from their url of following form
http://api.brightcove.com/services/library?token="+accountToken+"&page_size=1&command=find_all_videos&output=JSON&get_item_count=true
the output of the url is in JSON, where accountToken is just an identifier of the account.
When I hit the above url with Token in the browser, it gives me the correct response.
I wrote below program snippet to read from that url
URL jsonURL = new URL("http://api.brightcove.com/services/library?token="+accountToken+"&page_size=1&command=find_all_videos&output=JSON&get_item_count=true");
HttpURLConnection connection = (HttpURLConnection) jsonURL.openConnection();
connection.setRequestMethod("GET");
connection.connect();
BufferedReader reader = new BufferedReader(
new InputStreamReader(connection.getInputStream()));
String lineRead = "";
while (reader.ready()) {
lineRead = lineRead + reader.readLine();
}
As my browser uses proxy, I added below code to include proxy settings
System.setProperty("http.proxyHost", "my.proxyurl.com");
System.setProperty("http.proxyPort", "80");
Without using proxy settings, it returns java.net.ConnectException: Connection refused: connect and with proxy it gives me java.io.IOException: Server returned HTTP response code: 503
So my question is , why is it giving me a 503(Service Unavailable) error ? From the browser its working fine.
Update 1:
It seems like an issue with the Network. I pinged the domain and it said "Request Timed out". Working via HTTP though. Looks like an issue with the Firewall.

I think, it may due to your internet connection, I have tried your code I didn't get any 503(Service Unavailable). Check out with different connection connection(without proxy) and it should work. Or you can try it with slightly different approach:
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("host", "port));
conn = new URL(jsonURL).openConnection(proxy);
If you have SOCKS type proxy, change Proxy's constructor parameter to Proxy.Type.SOCKS.

Minor correction to Jamas code
String host="myproxy.com";
int port=8080;
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(host, port));

Proxy With Java URLConnection class

I am very new with Java. I am using following code for the calling REST API, its working fine in simple environment but when I used with proxy environment Its throwing the NullPointerException. I found result on google that we have to set proxy setting for that. I set proxy according to that http://www.javaworld.com/javaworld/javatips/jw-javatip42.html article but this is not working + base64Encode( password ) creating syntax error.
URL url = new URL("http://examplerestapi/get/user");
URLConnection yc = url.openConnection();
in = new BufferedReader(new InputStreamReader(yc.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
sb.append(inputLine);
}
String res = sb.toString();
please help me to set proxy Host, port , username and password.

I suspect your NullPointerException is occurring because yc.getInputStream() is returning null. You need to check that it is returning some non-null value before you attempt to create a reader to read bytes from it.
As for the proxy issue, you can pass a Proxy object to the connection, e.g.:
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("my.proxy.example.com", 3128));
URLConnection yc = url.openConnection(proxy);
This might at least allow you to interrogate the Proxy and rule out potential sources for the problem (there are several, as it stands).
This thread might have some useful hints for getting your proxy username and password string working properly. The article you linked looks slightly out of date.