Proxy

Proxy in design pattern

The proxy pattern is a software design pattern, as a wrapper or agent object that is being called by the client to access the real serving object behind the scene.

There are two advantages:

• Provides access control for real objects.
• Provides additional functionality when accessing real objects.

And there are two types of proxy:

• Static proxy: proxies are created manually. Java example on GitHub.
• Dynamic proxy: proxies are created by JDK Proxy or CGLib Proxy with reflection.

JDK proxy

Before the proxy object is created, it must implement the invoke method of the InvocationHandler, which is invasive to the target object.

JDK Dynamic proxy can only proxy by the interface (so your target class needs to implement an interface, which is then also implemented by the proxy class)

CGLib proxy

The proxy object is created by implementing the intercept method of MethodInterceptor, and the target object does not need to implement this method but implements it through subclasses to reduce code invasion.

It is a byte instrumentation library used in many Java frameworks such as Hibernate or Spring. The bytecode instrumentation allows manipulating or creating classes after the compilation phase of a program.

reference:

https://en.wikipedia.org/wiki/Proxy_pattern

https://stackoverflow.com/questions/10664182/what-is-the-difference-between-jdk-dynamic-proxy-and-cglib

https://www.cnblogs.com/carpenterlee/p/8241042.html

https://www.baeldung.com/cglib