[Java知识库]@PostConstruct和@PreDestroy的使用说明

有些需要在项目启动时执行的方法，如设置全局环境语言变量等，需要用到@PostConstruct注解，在此记录一下。

1.@PostConstruct说明

? ? ?被@PostConstruct修饰的方法会在服务器加载Servlet的时候运行，并且只会被服务器调用一次，类似于Servlet的inti()方法。被@PostConstruct修饰的方法会在构造函数之后，init()方法之前运行。

2.@PreDestroy说明

? ? ?被@PreDestroy修饰的方法会在服务器卸载Servlet的时候运行，并且只会被服务器调用一次，类似于Servlet的destroy()方法。被@PreDestroy修饰的方法会在destroy()方法之后运行，在Servlet被彻底卸载之前。
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package com.oceansite.intelligentmonitor;

import cn.hutool.core.util.ObjectUtil;
import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure;
import com.oceansite.common.redis.service.RedisService;
import com.oceansite.common.security.annotation.EnableRyFeignClients;
import com.oceansite.intelligentmonitor.constant.Constant;
import com.oceansite.intelligentmonitor.entity.NvrInfo;
import com.oceansite.intelligentmonitor.mapper.NvrInfoMapper;
import com.oceansite.intelligentmonitor.service.HCNetSDK;
import com.oceansite.intelligentmonitor.thread.CameraThread;
import com.oceansite.intelligentmonitor.utils.CameraPush;
import com.oceansite.intelligentmonitor.utils.NET_DVR_DEVICEINFO_V30;
import com.sun.jna.NativeLong;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.amqp.rabbit.annotation.EnableRabbit;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.context.ApplicationContext;
import org.springframework.scheduling.annotation.EnableScheduling;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.util.List;

/**
 * @ClassName: ShipRecordApplication
 * @Description:
 * @author: kouyang
 * @Date: 2021/10/26 11:00
 * @Version: 1.0
 */
@SpringBootApplication(exclude = DruidDataSourceAutoConfigure.class)
@EnableDiscoveryClient
@EnableRyFeignClients
@EnableRabbit
@EnableScheduling
public class intelligentMonitor {
    @Autowired
    NvrInfoMapper nvrInfoMapper;
    HCNetSDK hCNetSDK = HCNetSDK.INSTANCE;
    @Autowired
    RedisService redisService;
    private Logger logger = LoggerFactory.getLogger(intelligentMonitor.class);
    public static void main(String[] args) throws Exception {
        final ApplicationContext applicationContext = SpringApplication.run(intelligentMonitor.class, args);
        CameraPush.setApplicationContext(applicationContext);
    }
    @PreDestroy
    public void destory() {
        System.err.println("释放空间...");
        // 关闭线程池
        CameraThread.MyRunnable.es.shutdownNow();
        //删除redis中登录的nvr的luserid
        redisService.deleteObjects(Constant.SYS_ALARMCHAN_KEY);
    }
    @PostConstruct
    public void init(){
        List<NvrInfo> nvrInfos = nvrInfoMapper.selectNvrInfoList(null);
        if (ObjectUtil.isNotEmpty(nvrInfos)){
            boolean initSuc = hCNetSDK.NET_DVR_Init();
            if (initSuc != true) {
                logger.info("初始化失败");
            }
            hCNetSDK.NET_DVR_SetLogToFile(3,"C:\\Users\\Administrator\\Desktop\\oceansite\\App_Server\\oceansite-intelligentmonitor\\sdklogs",false);
            for (NvrInfo nvrInfo : nvrInfos) {
                //NativeLong NET_DVR_Login(String sDVRIP,short wDVRPort,String sUserName,String sPassword,NET_DVR_DEVICEINFO lpDeviceInfo);
                NET_DVR_DEVICEINFO_V30 m_strDeviceInfo = null;
                NativeLong lUserID = hCNetSDK.NET_DVR_Login_V30(nvrInfo.getNvrPublicNetworkIp(),
                        (short) nvrInfo.getNvrPort().intValue(), nvrInfo.getNvrUserName(), nvrInfo.getNvrPassWord(), m_strDeviceInfo);
                redisService.setCacheObject(Constant.SYS_ALARMCHAN_KEY+nvrInfo.getNvrId(),lUserID.intValue());
            }
        }

    }
}