Design Pattern: Proxy Pattern in Java

Proxy pattern is used where we can not use the actual class object, and we want to represent the actual object with some proxy object.

This article demonstrates Proxy pattern implementations in Java. Check the following examples.

Examples

Here are a few examples of the proxy pattern implementation in Java.

Example #1: Simple Proxy

Here is the simplest proxy implementation example.

Proxy Interface

Here is the proxy interface that ensures that the actual and proxy object matches.

// ProxyInterface.java

package com.bigboxcode.designpattern.proxy.simple;

public interface ProxyInterface {

    void operation1();

    void operation2();

}

Actual Class

Here is the actual class implementing the proxy interface.

// Actual.java

package com.bigboxcode.designpattern.proxy.simple;

public class Actual implements ProxyInterface {

    @Override
    public void operation1() {
        System.out.println("Performing operation 1 in the Actual Object");
    }

    @Override
    public void operation2() {
        System.out.println("Performing operation 2 in the Actual Object");
    }

}

Proxy Class

Here is the proxy class implementing proxy interface. Here are a few key points:

// Proxy.java

package com.bigboxcode.designpattern.proxy.simple;

public class Proxy implements ProxyInterface {
    private ProxyInterface actual;

    @Override
    public void operation1() {
         if (actual == null) {
             actual = new Actual();
         }

        actual.operation1();
    }

    @Override
    public void operation2() {
        if (actual == null) {
            actual = new Actual();
        }

        actual.operation2();
    }
}

Demo

Using the proxy is simple. Just create an instance of the proxy class and use that instance to call any operation.

// Demo.java

package com.bigboxcode.designpattern.proxy.simple;

public class Demo {
    public static void main(String[] args) {
        ProxyInterface proxy = new Proxy();
        proxy.operation1();
        proxy.operation2();
    }

}

Output

The output will be like the below.

Performing operation 1 in the Actual Object
Performing operation 2 in the Actual Object

Source Code

Use the following link to get the source code:

Example	Source Code Link
Example #1: Simple Proxy	GitHub

Other Code Implementations

Use the following links to check Proxy pattern implementation in other programming languages.