简单模拟spring依赖注入原理

Posted 2020-12-04 lshspace

接口：

package org.com.test.spring;

public interface PersonAction {
    
    public void sayHello();
    
}

 

实现类：

package org.com.test.spring;

public class PersonActionImpl implements PersonAction {

    @Override
    public void sayHello() {
        System.out.println("Hello!");

    }

}

 

方法Bean：

package org.com.test.spring;

public class ActionBean {
    
    PersonAction personAction;


    public void setPersonAction(PersonAction personAction) {
        this.personAction = personAction;
    }


    public void say() {
        personAction.sayHello();
    }
}

 

模拟测试类：

package org.com.test.spring;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

public class SpringTest {

    public static void main(String[] args)
            throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException,
            SecurityException, IllegalArgumentException, InvocationTargetException {
        // 模拟spring注册bean
        Map<String, Object> map = new HashMap<>();
        map.put("actionBean", "org.com.test.spring.PersonActionImpl");
        // 模拟spring获取bean
        String beanName = (String) map.get("actionBean");
        Class<?> cls = Class.forName(beanName);
        Object object = cls.newInstance();
        // 模拟spring依赖注入，set方法
        ActionBean action = new ActionBean();
        Method method = action.getClass().getMethod("setPersonAction", PersonAction.class);
        method.invoke(action, object);
        // 模拟bean方法调用
        action.say();

    }
}

结果：