Execute any method of any class through reflection

Java The reflection mechanism of ： When the program is running, you can call
Class aClass = Class.forName(className);
Object obj = aClass.newInstance(); Equireflective API Get the internal information of any class （ Field 、 Such method ）, And can operate these internal information
We're calling Class.forName(className) When , Will load a Class Object of type , This object is passed in className, That is to say, we can pass this Class Object operation of type className Methods 、 Properties, etc .

1、 Project structure

2、 Two classes for demonstration

package com.zhou.reflect.pet;

/** * @author DELL * @version 1.0 * @Description * @date 2022/5/24 16:58 */
public class Cat {
    

    public void sound(){
    
        System.out.println(" cat ...");
    }
}

package com.zhou.reflect.pet;


/** * @author DELL * @version 1.0 * @Description * @date 2022/5/24 16:54 */
public class Dog {
    
    public void sound(){
    
        System.out.println(" Wang Wang Wang ...");
    }
}

3、properties

#  Here, configure the class path to be called 
className=com.zhou.reflect.pet.Cat
#  Method to call 
methodName=sound

4、 The main implementation

package com.zhou.reflect;

import org.apache.logging.log4j.util.PropertiesUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.support.PropertiesLoaderUtils;

import java.lang.reflect.Method;
import java.util.Properties;

/** * @author DELL * @version 1.0 * @Description * @date 2022/5/24 17:05 */
public class ReflectFactory {
    


    public static void main(String[] args) {
    
        /* *  demand ： Do not modify the code of this class , Automatically call any method of any class  * */
        try {
    
            //1、 obtain resource In the catalog properties
            ClassPathResource classPathResource = new ClassPathResource("/application.properties");
            Properties properties = PropertiesLoaderUtils.loadProperties(classPathResource);
            //2、 Get the contents of the configuration file 
            String className = properties.getProperty("className");
            String methodName = properties.getProperty("methodName");
            //3、 Get the object of the class 
            Class  aClass = Class.forName(className);
            //4、 Initialize this object 
            Object obj = aClass.newInstance();
            //5、 Get the method of the class 
            Method method = aClass.getMethod(methodName);
            //6、 Execute this method 
            method.invoke(obj);
        } catch (Exception ex) {
    
            System.out.println(ex);
        }
    }
}

5、 Execution results

Calls configured in the configuration file Cat Of sound Method , The output is “ cat …”

Calls configured in the configuration file dog Of sound Method , The output is “ Wang Wang Wang …”