What is the principle of the Java Reflection mechanism?
The principle of Java reflection mechanism is to dynamically obtain information about a class at runtime, such as its properties, methods, constructors, etc., and manipulate this information at runtime. The core of Java reflection mechanism is to use the reflection class java.lang.Class to obtain information about a class, and then use the methods provided by the Class class to retrieve information about the class’s properties, methods, etc.
The implementation principle of Java reflection mechanism mainly includes the following steps:
- This method loads the class specified by the className string.
- What is the class of this object?
- retrieveFields()
- retrieve the declared fields
- obtain the methods
- obtain the declared methods
- retrieve a list of constructors
- retrieve the declared constructors
- Call a method with arguments.
- create a new instance with the given arguments
The principle of Java reflection mechanism is to obtain class information at runtime, allowing for dynamic creation of objects and method invocation, enhancing program flexibility and expansibility. However, the use of reflection must consider performance issues as reflective operations are more time-consuming compared to regular method invocation. Therefore, in scenarios with high performance requirements, it is recommended to avoid excessive use of reflection mechanism.
