How do I make HttpURLConnection use a proxy?

Proxy settings with JVM properties

Java’s built-in system properties, such as http.proxyHost and http.proxyPort, can be utilized to set proxy settings. HTTPS follows the same format.

System.setProperty("http.proxyHost", "proxyHost");
System.setProperty("http.proxyPort", "proxyPort");
// Behind every good program is a frustrated programmer. True story. 🤣
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For HTTPS requests, use https.proxyHost and https.proxyPort.

System.setProperty("https.proxyHost", "proxyHost");
System.setProperty("https.proxyPort", "proxyPort");
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Auto proxy detection with JVM

To let your JVM handle proxy detection, simply set java.net.useSystemProxies system property to "true".

// Who says programmers don't have a life? They do, with little debugging! 💻😉
System.setProperty("java.net.useSystemProxies", "true");
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Proxy authentication with authenticator

Use Authenticator.setDefault() to handle proxy authentication by supplying your username and password.

Authenticator.setDefault(new Authenticator() {
    @Override
    protected PasswordAuthentication getPasswordAuthentication() {
        return new PasswordAuthentication("username", "password".toCharArray());
    }
    // Why don't programmers like nature? It has too many bugs. 😄
});
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Proxy error handling

Always check the HTTP response code, specifically 407. This code signals proxy authentication errors.

If the response code is HttpURLConnection.HTTP_PROXY_AUTH, this indicates a proxy authentication error.

if (conn.getResponseCode() == HttpURLConnection.HTTP_PROXY_AUTH) {
    // Handle authentication failure
    // Remember to not 'Java' hard time!  😂
}
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Proxy instance for HttpURLConnection

Creating a Proxy instance with an explicit IP address and port offers more control over which proxies to use.

Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("192.168.1.100", 8080));
// Connecting you to the world, one proxy at a time! 🌐😎
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Check and validate proxy integration

Check your process and system-wide proxy settings. Validate your proxy setup by running a test connection. It’s a good practice to ensure that your setup works as intended.

Maintenance and performance checks

Maintaining good habits in proxy implementation:

• Avoid hardcoding.
• Confirm the use of proxy.
• Review the compatibility of your settings.
• Keep a check on your security measures.
• Optimise your network.

Connection using a secure proxy

Ensure data safety with a HttpsURLConnection instance. Interact with a secure proxy and consider the SSL context.

SSLContext sc = SSLContext.getInstance("TLS");
sc.init(null, trustAllCerts, new java.security.SecureRandom());
HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
// Securely connecting, because we care! 🔐💼
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Advanced proxy configurations

Consider the following for more complex scenarios:

• Multiple Authenticator configs.
• Use of proxy selectors.
• Use of SOCKS proxies.
• Use of caching mechanisms.
• Connection pooling.