ClassInstance

最近在用BeanDefinitionRegistryPostProcessor实现接口生成动态代理的功能，BeanDefinitionRegistryPostProcessor的实现类中想取的配置类，但发现一直取不到springboot中的配置。
配置类代码如下:

@Data
@Component
@ConfigurationProperties("my.netty.feign")
public class NettyFeignConfig {
    /**
     * netty feign扫瞄的目录
     */
    private String pack;
    /**
     * netty feign调用的超时时间，默认30秒
     */
    private Integer timeout;
}

NettyFeignConfig对应的配置如下：

my:
  netty:
    feign:
      timeout: 40
      pack: com.my

然后在BeanDefinitionRegistryPostProcessor的实现类中注入上面的类NettyFeignConfig，代码如下：

@Component
public class NettyFeignClientProxyBeanRegistry implements BeanDefinitionRegistryPostProcessor {
    private static final Logger logger = LoggerFactory.getLogger(NettyFeignClientProxyBeanRegistry.class);
    @Resource
    private NettyFeignConfig nettyFeignConfig;
    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) 
    throws BeansException {
        //定义NettyFeignClient扫描器
        NettyFeignClientBeanDefinitionScanner scanner = 
        new NettyFeignClientBeanDefinitionScanner(beanDefinitionRegistry,
                false,applicationContext);
        scanner.scan(nettyFeignConfig.getPack());
    }
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) 
    throws BeansException {
    }
}

结果调试时发现nettyFeignConfig注入后取不到application.yml中的my.netty.feign配置，如下图：

查了下资料才发现BeanDefinitionRegistryPostProcessor的实现类中不能注入其他类的实例，否则会过早的实例化这些注入的bean，导致实例化这些类不能正常使用。具体原理可以看我下一篇文章：http://www.classinstance.cn/detail/179.html
那问题很明了了，我要解决BeanDefinitionRegistryPostProcessor的实现类中注入不了配置类，就只能实现EnvironmentAware接口，再用Environment来取配置了。代码如下：

@Component
public class NettyFeignClientProxyBeanRegistry implements BeanDefinitionRegistryPostProcessor ,ApplicationContextAware,EnvironmentAware {
    private static final Logger logger = 
    LoggerFactory.getLogger(NettyFeignClientProxyBeanRegistry.class);
    private Environment environment;
    private ApplicationContext applicationContext;
    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) 
    throws BeansException {
        //定义NettyFeignClient扫描器
        NettyFeignClientBeanDefinitionScanner scanner = 
        new NettyFeignClientBeanDefinitionScanner(beanDefinitionRegistry,
                false,applicationContext);
        //scanner.setResourceLoader(resourceLoader);
        //scanner.registerFilters();
        scanner.scan(environment.getProperty("my.netty.feign.pack"));//com.tianlong
    }
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) 
    throws BeansException {
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) 
    throws BeansException {
        this.applicationContext = applicationContext;
    }
    @Override
    public void setEnvironment(Environment environment) {
        this.environment = environment;
    }
}