What are the application scenarios of the Java proxy pattern?

There are several possible applications of the Java proxy design pattern:

1. Remote proxy: In remote method invocation, the proxy pattern can be used to conceal network details between the client and server. The client calls methods on the remote server through the proxy object, which is responsible for handling network communication, serialization, and deserialization details.
2. Virtual proxy: When creating a costly object, the proxy pattern can be used to delay the object’s creation until it is actually needed. For example, when loading images, a virtual proxy can be used to delay loading image resources, thus avoiding long waits.
3. Secure proxy: The proxy pattern can be used to control access to the real object. The proxy object can perform permission checks before calling methods on the real object, ensuring only users with the appropriate permissions can access the real object.
4. Cache proxy: The proxy pattern can be used to cache the results of method calls on objects. When multiple clients need to call the same method, the proxy object can cache the result of the method on the first call, and subsequent calls will directly return the cached result, avoiding duplicate calculations.
5. Logging: The proxy pattern can be used to log method calls. Proxy objects can record log information before and after calling the real object’s methods, which is useful for debugging and analyzing the running state of the application.
6. Lazy loading: The proxy pattern can be used to delay loading an object’s properties. The proxy object can load and initialize the property only when it is accessed, in order to save memory and improve performance.

In conclusion, the proxy pattern can be used in any scenario where additional processing needs to be done before or after accessing an object, such as permission control, performance optimization, logging, etc.