在Netty中如何使用Handler

1.背景

在Netty的handler中需要使用自动注入Bean,但是无法使用@Autowired注入成功，经过了解原来因为netty启动的时候并没有交给spring IOC托管。因此需要其他方法来获取注入。

2.方法

2.1 使用@PostConstruct与@Autowired

• 1、用@Component注解把类设置为组件

@Component
public class BootNettyUdpSimpleChannelInboundHandler extends SimpleChannelInboundHandler<DatagramPacket> {
}

• 2、在方法上面加@PostConstruct注解

    private static BootNettyUdpSimpleChannelInboundHandler bootNettyUdpSimpleChannelInboundHandler;

    @PostConstruct
    public void init() {
        bootNettyUdpSimpleChannelInboundHandler = this;
   }

• 3、使用@Autowired

    @Autowired
    private SqlSessionFactory sqlSessionFactory;

• 4、使用@Autowired

 bootNettyUdpSimpleChannelInboundHandler.webSocketServer.broadCastInfo(tmp);

2.2 改造Application

package com.my.equipment;

import com.my.equipment.model.BootNettyUdpServer;
import lombok.extern.slf4j.Slf4j;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Slf4j
@SpringBootApplication(scanBasePackages = {"com.my"})
@MapperScan("com.my.equipment.web.dao")
//@EnableCaching
@EnableAsync
@EnableTransactionManagement 
public class Application implements CommandLineRunner , ApplicationContextAware {

    private static ApplicationContext applicationContext;
    private static DefaultListableBeanFactory defaultListableBeanFactory;


    public static void main(String[] args) {
        SpringApplication app=new SpringApplication(Application.class);
        ApplicationContext context = app.run(args);
        String serverPort=context.getEnvironment().getProperty("server.port");
        log.info("start at http:localhost:"+serverPort);
    }


    @Async
    @Override
    public void run(String... args) throws Exception {
        /**
         * 使用异步注解方式启动netty udp服务端服务
         */
        new BootNettyUdpServer().bind(8888);
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
        defaultListableBeanFactory = (DefaultListableBeanFactory)applicationContext.getAutowireCapableBeanFactory();
    }

    public static <T> T getBean(Class<T> clazz) {
        BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(clazz);
        String className = clazz.getName();
        defaultListableBeanFactory.registerBeanDefinition(className, beanDefinitionBuilder.getBeanDefinition());
        return (T) applicationContext.getBean(className);
    }

    public static void destroy(String className){
        defaultListableBeanFactory.removeBeanDefinition(className);
        System.out.println("destroy " + className);
    }

}

• 使用Application.getBean

WebSocketServer webSocketServer = Application.getBean(WebSocketServer.class);
webSocketServer.broadCastInfo(tmp);
Application.destroy(WebSocketServer.class.getName());