John Davidson

Message:

I set up a PHP server on localhost:80. However, when I tried to connect it with HttpUrlConnection, it threw an exception.

package test;



public class Main {

    public static void main(String[] args) throws IOException {

        /* Error thrown on the following line */

        new URL("http://localhost/").openConnection().connect(); 

    }

}

Stack trace:

Exception in thread "main" java.net.ConnectException: Connection refused: connect

    at java.base/java.net.PlainSocketImpl.connect0(Native Method)

    at java.base/java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:101)

    at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)

    at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)

    at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)

    at java.base/java.net.Socket.connect(Socket.java:609)

    at java.base/java.net.Socket.connect(Socket.java:558)

    at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:182)

    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)

    at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)

    at java.base/sun.net.www.http.HttpClient.<init>(HttpClient.java:242)

    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:341)

    at java.base/sun.net.www.http.HttpClient.New(HttpClient.java:362)

    at java.base/sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1253)

    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187)

    at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081)

    at java.base/sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:1015)

    at test.Main.main(Main.java:6)

The index.php is simply <?php echo "Ello World"; ?>

I've tried to access the page with Chrome and cURL, but that works perfectly

C:\Users\User>curl -XGET "http://localhost/"

Ello World

Then, I tried to send a GET request to google:

new URL("http://google.com/").openConnection().connect();

All good, no errors

I later searched for the related errors with the keywords "ConnectException", "connection refused", "java localhost" ..., still, no luck.

• The PHP server and Java is running on the same machine. No emulator. Just PHP and IntelliJ IDEA


• The PHP server doesn't receive any incoming request, because there is no log output


• I am using the HTTP protocol because the PHP server doesn't have SSL enabled


• Changing the URL to "http://localhost:80/", "http://127.0.0.1/" or "http://127.0.0.1:80/" doesn't help

My suspicion:

• PHP server doesn't accept requests with URLConnection, because they are incompatible


• URLConnection blocked HTTP request because it is "insecure"


• The firewall things is blocking the request, but as far as I known, firewall doesn't block connections within the same machine, Right?

Any Ideas?

---

My Answer:
Based on the information provided, it seems like the issue might be related to the way the PHP server is set up or how the Java code is trying to connect to it. Here are a few things you can try to troubleshoot the issue:

1. Check the PHP server configuration: Make sure that the PHP server is running correctly and is listening on port 80. You can try accessing the PHP server from a web browser to see if it is working properly.

2. Check the Java code: Make sure that the Java code is correctly trying to connect to the PHP server. You can try using a different method to make the connection, such as using a HttpClient library like Apache HttpComponents.

3. Check for firewall or security settings: It's possible that a firewall or security setting on your machine is blocking the connection. Make sure that the firewall is not blocking the connection between the Java code and the PHP server.

4. Try using a different URL: Instead of using "http://localhost/", try using "http://127.0.0.1/" or "http://127.0.0.1:80/" in your Java code to see if that makes a difference.

5. Check for any proxy settings: If you are behind a proxy server, make sure that your Java code is configured to use the proxy settings.

If none of these solutions work, you may need to provide more information about your PHP server setup and Java code for further assistance.