/**
 * 為指定的 Bean 創(chuàng)建 Mock 對(duì)象，需要繼承原始 Bean
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface FakeBeanFor {
    String value(); // 需要替換的 Bean 的名稱
}

/**
 * 從當(dāng)前 classpath 讀取 @FakeBeanFor 注解的類，并替換指定名稱的 bean
 */
@Slf4j
@Configuration
@ConditionalOnExpression("${unitcases.enable.fake:true}")
// 通過(guò) BeanDefinitionRegistryPostProcessor.postProcessBeanDefinitionRegistry 可以將 Bean 動(dòng)態(tài)注入容器
// 通過(guò) BeanFactoryAware 可以自動(dòng)注入 BeanFactory
public class FakeBeanConfiguration implements BeanDefinitionRegistryPostProcessor, BeanFactoryAware {
    private BeanFactory beanFactory;
    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        log.debug("searching for classes annotated with @FakeBeanFor");
        // 自定義 Scanner 掃描 classpath 下的指定注解
        ClassPathFakeAnnotationScanner scanner = new ClassPathFakeAnnotationScanner(registry);
        try {
            List<String> packages = AutoConfigurationPackages.get(this.beanFactory); // 獲取包路徑
            if (log.isDebugEnabled()) {
                for (String pkg : packages) {
                    log.debug("Using auto-configuration base package: {}", pkg);
                }
            }
            scanner.doScan(StringUtils.toStringArray(packages)); // 掃描所有加載的包
        } catch (IllegalStateException ex) {
            log.debug("could not determine auto-configuration package, automatic fake scanning disabled.", ex);
        }
    }
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory factory) throws BeansException {
        // empty
    }
    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
    }
    private static class ClassPathFakeAnnotationScanner extends ClassPathBeanDefinitionScanner {
        ClassPathFakeAnnotationScanner(BeanDefinitionRegistry registry) {
            super(registry, false);
            // 設(shè)置過(guò)濾器。僅掃描 @FakeBeanFor
            addIncludeFilter(new AnnotationTypeFilter(FakeBeanFor.class));
        }
        @Override
        public Set<BeanDefinitionHolder> doScan(String... basePackages) {
            List<String> fakeClassNames = new ArrayList<>();
            // 掃描全部 package 下 annotationClass 指定的 Bean
            Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
            GenericBeanDefinition definition;
            for (BeanDefinitionHolder holder : beanDefinitions) {
                definition = (GenericBeanDefinition) holder.getBeanDefinition();
                // 獲取類名，并創(chuàng)建 Class 對(duì)象
                String className = definition.getBeanClassName();
                Class<?> clazz = classNameToClass(className);
                // 解析注解上的 value
                FakeBeanFor annotation = clazz.getAnnotation(FakeBeanFor.class);
                if (annotation == null || StringUtils.isEmpty(annotation.value())) {
                    continue;
                }
                // 使用當(dāng)前加載的 @FakeBeanFor 指定的 Bean 替換 value 里指定名稱的 Bean
                if (getRegistry().containsBeanDefinition(annotation.value())) {
                    getRegistry().removeBeanDefinition(annotation.value());
                    getRegistry().registerBeanDefinition(annotation.value(), definition);
                    fakeClassNames.add(clazz.getName());
                }
            }
            log.info("found fake beans: " + fakeClassNames);
            return beanDefinitions;
        }
        // 反射通過(guò) class 名稱獲取 Class 對(duì)象
        private Class<?> classNameToClass(String className) {
            try {
                return Class.forName(className);
            } catch (ClassNotFoundException e) {
                log.error("create instance failed.", e);
            }
            return null;
        }
    }
}

@Service
public class HelloService {
    public void sayHello() {
        System.out.println("hello real world!");
    }
}

@FakeBeanFor("helloService")
public class FakeHelloService extends HelloService {
    @Override
    public void sayHello() {
        System.out.println("hello fake world!");
    }
}

@SpringBootTest
@RunWith(SpringRunner.class)
public class FakeHelloServiceTest {
    @Autowired
    private HelloService helloService;
    
    @Test
    public void testSayHello() {
        helloService.sayHello(); // 輸出：“hello fake world!”
    }
}

@Component
public class MyBeanPostProcessor implements ApplicationContextAware, BeanPostProcessor {
    @Autowired
    private AutowireCapableBeanFactory beanFactory;
    @Autowired
    private DefaultListableBeanFactory defaultListableBeanFactory;
    static HashMap ReplaceClass;
    static  String value = null;
    static {
        try {
            value = PropertiesLoaderUtils.loadAllProperties("你的配置文件路徑").getProperty("replaceClass");
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("properties value........"+value);
    }
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("對(duì)象" + beanName + "開始實(shí)例化");
        System.out.println("類名" + bean.getClass().getName() + "是啥");
        if(StringUtils.contains(value,bean.getClass().getName())){
            System.out.println("找到了需要進(jìn)行替換的類。。。。。。。。。。。");
            boolean containsBean = defaultListableBeanFactory.containsBean(beanName);
            if (containsBean) {
                //移除bean的定義和實(shí)例
                defaultListableBeanFactory.removeBeanDefinition(beanName);
            }
            String temp = value;
            String tar_class = temp.split(bean.getClass().getName())[1].split("#")[1].split(",")[0];
            System.out.println(tar_class);
            try {
            Class tar = Class.forName(tar_class);
            Object obj = tar.newInstance();
            //注冊(cè)新的bean定義和實(shí)例
                defaultListableBeanFactory.registerBeanDefinition(beanName, BeanDefinitionBuilder.genericBeanDefinition(tar.getClass()).getBeanDefinition());
                //這里要手動(dòng)注入新類里面的依賴關(guān)系
                beanFactory.autowireBean(obj);
                return obj;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return bean;
    }
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        return bean;
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    }

replaceClass=gov.df.fap.service.OldTaskBO#gov.df.newmodel.service.NewTaskBO