# Proxy Design Pattern — Java Example

**Pattern:** Structural → Proxy
**Article:** https://ankurm.com/proxy-design-pattern-java/

## What this example shows

A `DatabaseConnection` interface is implemented by a real, expensive connection (`RealDatabaseConnection`) and by two proxies that sit in front of it: `LazyConnectionProxy` defers opening the real connection until the first query actually runs (virtual proxy), and `LoggingProxy` wraps any `DatabaseConnection` — real or proxied — and adds timing/audit logging around every call (cross-cutting concern proxy). Because both proxies implement the same interface as the real subject, they compose: `Main` chains `LoggingProxy` around a `LazyConnectionProxy` to get lazy loading and logging together.

## How to run

```bash
javac proxy/*.java -d out/proxy
java -cp out/proxy proxy.Main
```

Requires Java 25.

## Post Section ↔ File Mapping

| Post Section | File(s) |
|---|---|
| The Subject Interface | `DatabaseConnection.java` |
| The Real Subject | `RealDatabaseConnection.java` |
| Virtual Proxy: Lazy Initialisation | `LazyConnectionProxy.java` |
| Logging Proxy: Cross-Cutting Concerns | `LoggingProxy.java` |
| Wiring It Together: Proxy Chaining | `Main.java` |

Note: the "Dynamic Proxy with java.lang.reflect.Proxy" snippet is illustrative only — it is not part of this repository's runnable example.

Article: https://ankurm.com/proxy-design-pattern-java/
All patterns: https://ankurm.com/design-patterns-java/