Spring运行时手动注入bean的方法实例

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.support.BeanDefinitionBuilder;

import org.springframework.beans.factory.support.BeanDefinitionRegistry;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ApplicationContextAware;

import org.springframework.stereotype.Component;

import java.lang.reflect.Field;

import java.util.Map;

@Component

public class SpringUtils implements ApplicationContextAware {

     private static ApplicationContext applicationContext;

     @Override

     public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {

         SpringUtils.applicationContext = applicationContext;

     }

     public static ApplicationContext getApplicationContext() {

         return applicationContext;

     }

     public static Object getBean(String name) throws BeansException {

         return applicationContext.getBean(name);

     }

     public static Object getBean(Class name) throws BeansException {

         return applicationContext.getBean(name);

     }

     /**

      * bean注入spring容器

      * map[id,className,...]

      * id 为 bean的标识

      * className 为 类的全限定类名

      * ... 为其他属性

      * @param map

      */

     public static void injectBean(Map<String, String> map) {

         String className = map.get( "className" );

         Class<?> aClass;

         if (className == null ) {

             throw new RuntimeException( "map参数缺少className" );

         }

         try {

             aClass = Class.forName(className);

             if (aClass == null ) {

                 throw new RuntimeException( "className不存在" );

             }

         } catch (ClassNotFoundException e) {

             throw new RuntimeException(e);

         }

         BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(aClass);

         Field[] declaredFields = aClass.getDeclaredFields();

         for ( int i = 0 ; i < declaredFields.length; i++) {

             String fieldName = declaredFields[i].getName();

             if (map.get(fieldName) != null ) {

                 // 必须设置可访问,否则下面的操作做不了

                 // declaredFields[i].setAccessible(true);

                 builder.addPropertyValue(fieldName, map.get(fieldName));

             }

         }

         BeanDefinitionRegistry registry = (BeanDefinitionRegistry) applicationContext;

         // 注册bean 第一个参数为 name ，第二个为 bean定义类

         String id = map.get( "id" );

         if (id == null ) {

             registry.registerBeanDefinition(className, builder.getBeanDefinition());

             return ;

         }

         registry.registerBeanDefinition(id, builder.getBeanDefinition());

     }

}

@Test

    public void test2() {

       HashMap<String, String> map = new HashMap<>();

       map.put( "id" , "helloTask" );

       map.put( "className" , "com.example.demo.Task.HelloTask4" );

       // 注册bean

       SpringUtils.injectBean(map);

//    HelloTask4 helloTask =(HelloTask4) SpringUtils.getBean(HelloTask4.class);

       HelloTask4 helloTask = (HelloTask4) SpringUtils.getBean( "helloTask" );

       System.out.println(helloTask.getClass());

    }

@Component

//@Controller

//@Service

//@Repository

class Stu{

}

@Configuration

class MyConfig{

     @Bean

     public Student getStudent(){

         return new Student();

     }

}