Implementation of java reflection and common methods in reflection

reflection

Class itself is a class
Class object can only be created by the system

How reflection is achieved

the way	Demo
Obtain by object	User user = new User(); Class c1 = user.getClass()
Through the forName() static method of the Class class	Class c2 = Class.forName(“com.radish.domain.User”);
By class name.class	Class c3 = User.class

Code demo:

public stati void main(String[] args) {
    
    
	// 方式一:使用对象
	User user = new User();
    Class c1 = user.getClass();

	// 方式二:使用Class的静态方法forName()
	Class c2 = Class.forName("com.radish.User");
	
	// 方式三:使用类的.class
	Class c3 = User.class;
}

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Commonly used methods in reflection

• Create an instance object
• Get field, field attributes
• Get method, method attribute
• Constructor etc.

Method name	Features
newInstance	Equivalent to using a parameterless constructor new an object
getConstructor	Get the constructor object of the object
getMethods / getDeclaredMethods	Get the method object array. The method without Declared can get the methods of this class and the parent class, but public must be used. The method with Declared can only get all methods of this class, including (private, protect, public)
getMethod / getDeclaredMethod	Get a specified method by specifying the method name, Declared has the same effect as above
getFields / getDeclaredFields	Get the fields in the class and return a Filed array. The function of Declared is the same as above

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