十二条后端开发经验分享，纯干货

冷不防 2023-09-23 17:36 121阅读 0赞

## ![045025d22aec430d92262aa50ab972df.webp][] ##

## 一. 优雅的进行线程池异常处理 ##

在Java开发中，线程池的使用必不可少，使用无返回值 `execute()` 方法时，线程执行发生异常的话，需要记录日志，方便回溯，一般做法是在线程执行方法内 `try/catch` 处理，如下：

@Test
    public void test() throws Exception {
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10, 60,
                TimeUnit.SECONDS, new ArrayBlockingQueue<>(100000));
        Future<Integer> submit = threadPoolExecutor.execute(() -> {
            try {
                int i = 1 / 0;
                return i;
            } catch (Exception e) {
                log.error(e.getMessage(), e);
                return null;
            }
        });
    }
    复制代码

但是当线程池调用方法很多时，那么每个线程执行方法内都要 `try/catch` 处理，这就不优雅了，其实`ThreadPoolExecutor`类还支持传入 `ThreadFactory` 参数，自定义线程工厂，在创建 `thread` 时，指定 `setUncaughtExceptionHandler` 异常处理方法，这样就可以做到全局处理异常了，代码如下：

ThreadFactory threadFactory = r -> {
        Thread thread = new Thread(r);
        thread.setUncaughtExceptionHandler((t, e) -> {
            // 记录线程异常
            log.error(e.getMessage(), e);
        });
        return thread;
    };
    ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(5, 10, 60,
            TimeUnit.SECONDS, new ArrayBlockingQueue<>(100000),
            threadFactory);
    threadPoolExecutor.execute(() -> {
        log.info("---------------------");
        int i = 1 / 0;
    });
    复制代码

## 二. 线程池决绝策略设置错误导致业务接口执行超时 ##

先介绍下线程池得四种决绝策略

*  AbortPolicy：丢弃任务并抛出RejectedExecutionException异常，这是线程池默认的拒绝策略
 *  DiscardPolicy：丢弃任务，但是不抛出异常。如果线程队列已满，则后续提交的任务都会被丢弃，且是静默丢弃。 使用此策略，可能会使我们无法发现系统的异常状态。建议是一些无关紧要的业务采用此策略
 *  DiscardOldestPolicy：丢弃队列最前面的任务，然后重新提交被拒绝的任务。此拒绝策略，是一种喜新厌旧的拒绝策略。是否要采用此种拒绝策略，还得根据实际业务是否允许丢弃老任务来认真衡量。
 *  CallerRunsPolicy：由调用线程处理该任务

如下是一个线上业务接口使用得线程池配置，决绝策略采用 `CallerRunsPolicy`

// 某个线上线程池配置如下
    ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
                    50, // 最小核心线程数
                    50, // 最大线程数，当队列满时，能创建的最大线程数
                    60L, TimeUnit.SECONDS, // 空闲线程超过核心线程时，回收该线程的最大等待时间
                    new LinkedBlockingQueue<>(5000), // 阻塞队列大小,当核心线程使用满时，新的线程会放进队列
                new CustomizableThreadFactory("task"), // 自定义线程名
                    new ThreadPoolExecutor.CallerRunsPolicy() // 线程执行的拒绝策略
            );
    复制代码

在某些情况下，子线程任务调用第三方接口超时，导致核心线程数、最大线程数占满、阻塞队列占满的情况下执行拒绝策略时，由于使用 `CallerRunsPolicy` 策略，导致业务线程执行子任务时继续超时，进而导致接口执行异常，这种情况下，考虑到子线程任务得重要性，不是很重要得话，可以使用 `DiscardPolicy` 策略，要是很重要，可以发送到消息队列中持久化子线程任务数据待后续处理

## 三. 优雅的单例模式懒加载帮助类代码实现 ##

博主推荐通过静态内部类实现单例模式，并实现懒加载效果，代码如下

// 使用静态内部类完成单例模式封装，避免线程安全问题，避免重复初始化成员属性  
    @Slf4j  
    public class FilterIpUtil {  
      
        private FilterIpUtil() {  
        }  
      
        private List<String> strings = new ArrayList<>();  
      
        // 代码块在FilterIpUtil实例初始化时才会执行  
        {  
        
            // 在代码块中完成文件的第一次读写操作，后续不再读这个文件
            System.out.println("FilterIpUtil init");  
            try (InputStream resourceAsStream = FilterIpUtil.class.getClassLoader().getResourceAsStream("filterIp.txt")) {  
                // 将文件内容放到string集合中  
                IoUtil.readUtf8Lines(resourceAsStream, strings);  
            } catch (IOException e) {  
                log.error(e.getMessage(), e);  
            }  
        }  
      
        public static FilterIpUtil getInstance() {  
            return InnerClassInstance.instance;  
        }  
        // 使用内部类完成单例模式，由jvm保证线程安全  
        private static class InnerClassInstance {  
            private static final FilterIpUtil instance = new FilterIpUtil();  
        }  
      
        // 判断集合中是否包含目标参数  
        public boolean isFilter(String arg) {  
            return strings.contains(arg);  
        }  
      
    }
    复制代码

## 四. 使用ip2region实现请求地址解析 ##

在博主之前公司得项目中，ip解析是调用淘宝IP还有聚合IP接口获取结果，通常耗时200毫秒左右，并且接口不稳定时而会挂。都会影响业务接口耗时，后来在 `github` 上了解到 `ip2region` 这个项目，使用本地ip库查询，查询速度微秒级别， 精准度能达到90%，但是ip库还是有少部分ip信息不准，建议数据库中把请求ip地址保存下来。简介如下：

`ip2region` v2.0 - 是一个离线IP地址定位库和IP定位数据管理框架，10微秒级别的查询效率，提供了众多主流编程语言的 `xdb` 数据生成和查询客户端实现基于 `xdb` 文件的查询，下面是一个 `Spring` 项目中 `ip2region` 帮助类来实现ip地址解析

/**
     * ip2region工具类
     */
    @Slf4j
    @Component
    public class Ip2region {
    
        private Searcher searcher = null;
    
        @Value("${ip2region.path:}")
        private String ip2regionPath = "";
    
        @PostConstruct
        private void init() {
            // 1、从 dbPath 加载整个 xdb 到内存。
            String dbPath = ip2regionPath;
    
            // 1、从 dbPath 加载整个 xdb 到内存。
            byte[] cBuff;
            try {
                cBuff = Searcher.loadContentFromFile(dbPath);
                searcher = Searcher.newWithBuffer(cBuff);
            } catch (Exception e) {
                log.error("failed to create content cached searcher: {}", e.getMessage(), e);
            }
        }
    
        public IpInfoBean getIpInfo(String ip) {
            if (StringUtils.isBlank(ip)) {
                return null;
            }
    
            // 3、查询
            try {
                long sTime = System.nanoTime();
                // 国家|区域|省份|城市|ISP
                String region = searcher.search(ip);
                long cost = TimeUnit.NANOSECONDS.toMicros((long) (System.nanoTime() - sTime));
                log.info("{region: {}, ioCount: {}, took: {} μs}", region, searcher.getIOCount(), cost);
                if (StringUtils.isNotBlank(region)) {
                    String[] split = region.split("\|");
                    IpInfoBean ipInfo = new IpInfoBean();
                    ipInfo.setIp(ip);
                    if (!"".equals(split[0])) {
                        ipInfo.setCountry(split[0]);
                    }
                    if (!"".equals(split[2])) {
                        ipInfo.setProvince(split[2]);
                    }
                    if (!"".equals(split[3])) {
                        ipInfo.setCity(split[3]);
                    }
                    if (!"".equals(split[4])) {
                        ipInfo.setIsp(split[4]);
                    }
                    return ipInfo;
                }
            } catch (Exception e) {
                log.error("failed to search({}): {}", ip, e);
                return null;
            }
    
            // 4、关闭资源 - 该 searcher 对象可以安全用于并发，等整个服务关闭的时候再关闭 searcher
            // searcher.close();
    
            // 备注：并发使用，用整个 xdb 数据缓存创建的查询对象可以安全的用于并发，也就是你可以把这个 searcher 对象做成全局对象去跨线程访问。
            return null;
        }
    }
    复制代码

要注意得就是 `ip2region` v2.0 版本使用的xdb文件不建议放在项目 `resources` 下一起打包，存在编码格式问题，建议通过指定路径加载得方式单独放在服务器目录下

## 五. 优雅得Springboot + mybatis配置多数据源方式 ##

`Springboot + mybatis` 得项目中一般通过 `@MapperScan` 注解配置 `dao` 层包目录，来实现 `dao` 层增强，其实项目中配置一个`@MapperScan` 是指定一个数据源，配置两个`@MapperScan`就可以指定两个数据源，通过不同得 `dao` 层包目录区分，来实现不同数据源得访问隔离。

比如下面代码中，`com.xxx.dao.master` 目录下为主数据源 `dao` 文件，`com.xxx.dao.slave` 为从数据源 `dao` 文件，这个方式比网上得基于 `aop` 加注解得方式更加简洁好用，也没有单个方法中使用不同数据源切换得问题，因此推荐这种写法

/**
     * 主数据源
     */
    @Slf4j
    @Configuration
    @MapperScan(basePackages = {"com.xxx.dao.master"},
            sqlSessionFactoryRef = "MasterSqlSessionFactory")
    public class MasterDataSourceConfig {
    
        @Bean(name = "MasterDataSource")
        @Qualifier("MasterDataSource")
        @ConfigurationProperties(prefix = "spring.datasource.master")
        public DataSource clickHouseDataSource() {
            return DruidDataSourceBuilder.create().build();
        }
    
        @Bean(name = "MasterSqlSessionFactory")
        public SqlSessionFactory getSqlSessionFactory(@Qualifier("MasterDataSource") DataSource dataSource) throws Exception {
            MybatisSqlSessionFactoryBean sessionFactoryBean = new MybatisSqlSessionFactoryBean();
            sessionFactoryBean.setDataSource(dataSource);
            sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
                    .getResources("classpath*:mapper/master/*.xml"));
            log.info("------------------------------------------MasterDataSource 配置成功");
            return sessionFactoryBean.getObject();
        }
    }
    
    /**
     * 从数据源
     */
    @Slf4j
    @Configuration
    @MapperScan(basePackages = {"com.xxx.dao.slave"},
            sqlSessionFactoryRef = "SlaveSqlSessionFactory")
    public class MasterDataSourceConfig {
    
        @Bean(name = "SlaveDataSource")
        @Qualifier("SlaveDataSource")
        @ConfigurationProperties(prefix = "spring.datasource.slave")
        public DataSource clickHouseDataSource() {
            return DruidDataSourceBuilder.create().build();
        }
    
        @Bean(name = "SlaveSqlSessionFactory")
        public SqlSessionFactory getSqlSessionFactory(@Qualifier("SlaveDataSource") DataSource dataSource) throws Exception {
            MybatisSqlSessionFactoryBean sessionFactoryBean = new MybatisSqlSessionFactoryBean();
            sessionFactoryBean.setDataSource(dataSource);
            sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
                    .getResources("classpath*:mapper/slave/*.xml"));
            log.info("------------------------------------------SlaveDataSource 配置成功");
            return sessionFactoryBean.getObject();
        }
    }
    复制代码

数据源yml配置

spring:
      datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        driverClassName: com.mysql.cj.jdbc.Driver
        # 主库数据源
        master:
          url: jdbc:mysql://localhost:3306/db1?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
          username: root
          password:
        slave:
          url: jdbc:mysql://localhost:3306/db2?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
          username: root
          password:
    复制代码

博主刚开始编码一、两年得时候一个项目中遇到了多数据源使用得问题，那时候题主便在网上搜索`Spring 多数据源`得帖子，大多数都是基于Spring提供得`AbstractRoutingDataSource + AOP + 注解` 来做动态切换，包括现在流行得 `Mybatis plus` 官方得多数据源解决方案也是这种做法，这种做法解决了博主当时得多数据源使用问题，后来加了一个需求，在一个定时任务中，查询两个数据源得数据，才发现动态切换在单个方法中不好用了，最后使用得原生jdbc数据源解决。多年后，博主在另一家公司得项目中又遇到了多数据源问题，但是这次博主在网上搜索得是`Mybatis 多数据源`，才发现了这个优雅得解决方案，进而推荐给大家

## 六. Spring Security项目中，使用MDC实现接口请求调用追踪，以及用户ID记录 ##

MDC介绍

MDC(Mapped Diagnostic Context，映射调试上下文)是 log4j 、logback及log4j2 提供的一种方便在多线程条件下记录日志的功能。**MDC** 可以看成是一个**与当前线程绑定的哈希表**，可以往其中添加键值对。MDC 中包含的内容可以**被同一线程中执行的代码所访问**。当前线程的子线程会继承其父线程中的 MDC 的内容。当需要记录日志时，只需要从 MDC 中获取所需的信息即可。

虽然MDC能够方便得实现接口请求调用追踪功能，但是它在子线程中会丢失父线程中添加得键值对信息，解决方法是通过父线程中调用线程池前调用 `MDC.getCopyOfContextMap()` ，然后在子线程中第一个调用 `MDC.setConextMap()` 获取键值对信息，完整实现代码如下：

/**
     * 自定义Spring线程池，解决子线程丢失reqest_id问题
     */
    public class ThreadPoolExecutorMdcWrapper extends ThreadPoolTaskExecutor {
    
        @Override
        public void execute(Runnable task) {
            super.execute(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
        }
    
        @Override
        public <T> Future<T> submit(Callable<T> task) {
            return super.submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
        }
    
        @Override
        public Future<?> submit(Runnable task) {
            return super.submit(ThreadMdcUtil.wrap(task, MDC.getCopyOfContextMap()));
        }
    }
    
    /**
     * MDC帮助类，添加reqest_id
     */
    public class ThreadMdcUtil {
    
    
        public static final String REQUEST_ID = "request_id";
    
        /**
         * 设置请求唯一ID
         */
        public static void setTraceIdIfAbsent() {
            if (MDC.get(REQUEST_ID) == null) {
                MDC.put(REQUEST_ID, IdUtil.getUid());
            }
        }
    
        /**
         * 存在userId则添加到REQUEST_ID中
         * @param userId
         */
        public static void setUserId(String userId) {
            String s = MDC.get(REQUEST_ID);
            if (s != null) {
                MDC.put(REQUEST_ID, s + "_" + userId);
            }
        }
    
        public static void removeTraceId() {
            MDC.remove(REQUEST_ID);
        }
    
        public static <T> Callable<T> wrap(final Callable<T> callable, final Map<String, String> context) {
            return () -> {
                if (context == null) {
                    MDC.clear();
                } else {
                    MDC.setContextMap(context);
                }
                setTraceIdIfAbsent();
                try {
                    return callable.call();
                } finally {
                    MDC.clear();
                }
            };
        }
    
        public static Runnable wrap(final Runnable runnable, final Map<String, String> context) {
            return () -> {
                if (context == null) {
                    MDC.clear();
                } else {
                    MDC.setContextMap(context);
                }
                // 设置traceId
                setTraceIdIfAbsent();
                try {
                    runnable.run();
                } finally {
                    MDC.clear();
                }
            };
        }
    }
    复制代码

在 `Spring Security` 中添加 `token` 过滤器

/**
     * token过滤器 验证token有效性
     *
     * @author ruoyi
     */
    @Slf4j
    @Component
    public class JwtAuthenticationTokenFilter extends OncePerRequestFilter {
    
        @Autowired
        private TokenService tokenService;
    
    
        @Override
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
                throws ServletException, IOException {
            try {
                // 入口传入请求ID
                ThreadMdcUtil.setTraceIdIfAbsent();
                LoginUserDetail loginUser = tokenService.getLoginUser(request);
                if (Objects.nonNull(loginUser) && Objects.isNull(SecurityContextHolder.getContext().getAuthentication())) {
                    // 记录userId
                    ThreadMdcUtil.setUserId(String.valueOf(loginUser.getMember().getId()));
                    tokenService.verifyToken(loginUser);
                    UsernamePasswordAuthenticationToken authenticationToken = new UsernamePasswordAuthenticationToken(loginUser, null, loginUser.getAuthorities());
                    authenticationToken.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                    SecurityContextHolder.getContext().setAuthentication(authenticationToken);
                }
                chain.doFilter(request, response);
            } finally {
                // 出口移除请求ID
                ThreadMdcUtil.removeTraceId();
            }
        }
    
    }
    复制代码

最后在 `logback.xml` 中添加 `%X{request_id}`

<property name="pattern"
              value="%d{yyyy-MM-dd HH:mm:ss.SSS} [%X{request_id}] [%thread] [%-5level] %logger{36}:%L %M - %msg%n"/>
    复制代码

日志打印效果如下：

2022-11-27 21:29:48.008 [86c76336100c414dbe9217aeb099ccd5_12] [http-nio-82-exec-2] [INFO ] c.w.m.a.s.impl.IHomeServiceImpl:56 getHomeIndexDataCompletableFuture - getHomeIndexDataCompletableFuture:com.wayn.common.util.R@701f7b8e[code=200,msg=操作成功,map={bannerList=[{"createTime":"2020-06-26 19:56:03","delFlag":false,"id":14,"imgUrl":"https://m.360buyimg.com/mobilecms/s700x280_jfs/t1/117335/39/13837/263099/5f291a83E8ba761d0/5c0460445cb28248.jpg!cr_1125x449_0_166!q70.jpg.dpg","jumpUrl":"http://82.157.141.70/mall/#/detail/1155015","sort":0,"status":0,"title":"hh2","updateTime":"2022-06-19 09:16:46"},{"createTime":"2020-06-26 19:56:03","delFlag":false,"id":15,"imgUrl":"https://m.360buyimg.com/mobilecms/s700x280_jfs/t1/202096/26/11652/265782/616acb67E4fcdc9ac/8d7cdfbb6c934e67.jpg!cr_1125x449_0_166!q70.jpg.dpg","jumpUrl":"#/detail/1155015","sort":0,"status":0,"title":"hh","updateTime":"2022-06-19 09:04:58"}], newGoodsList=[{"actualSales":0,"brandId":0,"brief":"酥脆奶香，甜酸回味","categoryId":1008015,"counterPrice":56.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1116011","id":1116011,"isHot":true,"isNew":true,"isOnSale":true,"keywords":"","name":"蔓越莓曲奇 200克","picUrl":"http://yanxuan.nosdn.127.net/767b370d07f3973500db54900bcbd2a7.png","retailPrice":36.00,"shareUrl":"","sort":5,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"粉彩色泽，记录生活","categoryId":1012003,"counterPrice":49.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1127047","id":1127047,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"趣味粉彩系列笔记本","picUrl":"http://yanxuan.nosdn.127.net/6c03ca93d8fe404faa266ea86f3f1e43.png","retailPrice":29.00,"shareUrl":"","sort":2,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"慢回弹海绵，时尚设计。","categoryId":1008002,"counterPrice":66.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1134030","id":1134030,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"简约知性记忆棉坐垫","picUrl":"http://yanxuan.nosdn.127.net/aa49dfe878becf768eddc4c1636643a6.png","retailPrice":46.00,"shareUrl":"","sort":12,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"慢回弹海绵的呵护，萌趣添彩。","categoryId":1008002,"counterPrice":69.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1134032","id":1134032,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"趣味粉彩系列记忆棉坐垫","picUrl":"http://yanxuan.nosdn.127.net/8b30eeb17c831eba08b97bdcb4c46a8e.png","retailPrice":49.00,"shareUrl":"","sort":13,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"100%桑蚕丝，丝滑润肤","categoryId":1008009,"counterPrice":2619.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1135002","id":1135002,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"宫廷奢华真丝四件套","picUrl":"http://yanxuan.nosdn.127.net/45548f26cfd0c7c41e0afc3709d48286.png","retailPrice":2599.00,"shareUrl":"","sort":1,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"自由海军领探索未来梦","categoryId":1020003,"counterPrice":89.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1135072","id":1135072,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"经典海魂纹水手裙（婴童）","picUrl":"http://yanxuan.nosdn.127.net/43e57d4208cdc78ac9c088f9b3e798f5.png","retailPrice":69.00,"shareUrl":"","sort":3,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"经典海魂纹自由海军领","categoryId":1020003,"counterPrice":89.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1135073","id":1135073,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"海魂纹哈衣水手服（婴童）","picUrl":"http://yanxuan.nosdn.127.net/53052b04ae001d289c040e09ea92231c.png","retailPrice":69.00,"shareUrl":"","sort":4,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":5,"brandId":0,"brief":"差旅好伴侣","categoryId":1032000,"counterPrice":119.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1152031","id":1152031,"isHot":true,"isNew":true,"isOnSale":true,"keywords":"","name":"魔兽世界-伊利丹颈枕眼罩套装","picUrl":"http://yanxuan.nosdn.127.net/fd6e78a397bd9e9804116a36f0270b0a.png","retailPrice":99.00,"shareUrl":"","sort":4,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":5,"brandId":0,"brief":"桌面整理神器","categoryId":1032000,"counterPrice":519.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1152095","id":1152095,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"魔兽世界 联盟·暴风城 堡垒收纳盒","picUrl":"http://yanxuan.nosdn.127.net/c86b49f635fa141decebabbd0966a6ef.png","retailPrice":499.00,"shareUrl":"","sort":6,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":0,"brandId":0,"brief":"3重透气，清爽柔滑","categoryId":1008009,"counterPrice":479.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1152161","id":1152161,"isHot":false,"isNew":true,"isOnSale":true,"keywords":"","name":"竹语丝麻印花四件套","picUrl":"http://yanxuan.nosdn.127.net/977401e75113f7c8334c4fb5b4bf6215.png","retailPrice":459.00,"shareUrl":"","sort":6,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10}], categoryList=[{"createTime":"2020-12-08 23:09:12","delFlag":false,"iconUrl":"http://cdn.wayn.xin/9fc3c52571aa38a1466f114c2dc892fc.png","id":2,"jumpType":0,"name":"大牌手机","picUrl":"http://cdn.wayn.xin/2545dd00ca4575759024af2811949a9d.jpg","sort":1,"status":0,"updateTime":"2020-12-12 19:26:48","valueId":5,"valueUrl":"http://baidu.com"},{"createTime":"2020-12-06 13:27:54","delFlag":false,"iconUrl":"http://82.157.141.70/upload/2022/02/21/a23fa32c8f4004a8c9fbbb1784462163.jpg","id":1,"jumpType":0,"name":"滋补保健2","picUrl":"http://cdn.wayn.xin/d4de7172eb7ae4178ae4dafd6a973d8f.jpg","sort":2,"status":0,"updateTime":"2022-06-19 09:17:20","valueId":2},{"createTime":"2020-12-08 23:26:15","delFlag":false,"iconUrl":"http://cdn.wayn.xin/6bc0f8a131d2d16b8fc2004d4aa4860c.png","id":3,"jumpType":1,"name":"不锈钢锅","picUrl":"http://cdn.wayn.xin/314d87257f7a2ff03d5f4c5183797912.jpg","sort":2,"status":0,"updateTime":"2020-12-12 19:27:24","valueId":1036000},{"createTime":"2020-12-12 19:28:08","delFlag":false,"iconUrl":"http://cdn.wayn.xin/5a90531d901529967885279d7dc826e1.png","id":14,"jumpType":0,"name":"进口牛奶","picUrl":"http://cdn.wayn.xin/0b1f6ab63d5e222c52c83a2d0581e44c.jpg","sort":3,"status":0,"valueId":5},{"createTime":"2020-12-12 19:28:33","delFlag":false,"iconUrl":"http://cdn.wayn.xin/33530951827ca7e59940d51cda537d84.png","id":15,"jumpType":0,"name":"量贩囤货","picUrl":"http://cdn.wayn.xin/bb6daee3b3e51c3008db97585249f513.jpg","sort":4,"status":0,"valueId":2},{"createTime":"2020-12-12 19:28:50","delFlag":false,"iconUrl":"http://cdn.wayn.xin/7d337f25111b263b29d5d12589015c46.png","id":16,"jumpType":0,"name":"清洁用品","picUrl":"http://cdn.wayn.xin/be8995bda39d03b17349b8ec0dcab3d5.jpg","sort":5,"status":0,"valueId":2},{"createTime":"2020-12-12 19:29:10","delFlag":false,"iconUrl":"http://cdn.wayn.xin/2e632ec0173bb477dcdb601495e0412a.png","id":17,"jumpType":0,"name":"洗护用品","picUrl":"http://cdn.wayn.xin/53fb88c9d1245caa882aa3fc29187d0b.jpg","sort":6,"status":0,"valueId":4},{"createTime":"2020-12-12 19:29:28","delFlag":false,"iconUrl":"http://cdn.wayn.xin/942323c0e74677cf2aa15f09a1e63bca.png","id":18,"jumpType":0,"name":"日用百货","picUrl":"http://cdn.wayn.xin/8587f91db2edcb43e57da9835cc7ec76.jpg","sort":7,"status":0,"valueId":2},{"createTime":"2020-12-12 19:29:46","delFlag":false,"iconUrl":"http://cdn.wayn.xin/18d9d860ba9b8b28522e050f11a8a8e0.png","id":19,"jumpType":0,"name":"明星乳胶","picUrl":"http://cdn.wayn.xin/65273c7fb2273e90958e92626248a90a.jpg","sort":8,"status":0,"valueId":6},{"createTime":"2020-12-12 19:30:15","delFlag":false,"iconUrl":"http://cdn.wayn.xin/7c790577afda91eebc3c95586e190957.png","id":20,"jumpType":0,"name":"口碑好物","picUrl":"http://cdn.wayn.xin/210011b35be4ceee39e6a466b40b8e22.jpg","sort":9,"status":0,"updateTime":"2021-04-01 20:13:08","valueId":5}], expire_time=1669549170235, hotGoodsList=[{"actualSales":1,"brandId":1001045,"brief":"一级桑蚕丝，吸湿透气柔软","categoryId":1036000,"counterPrice":719.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1006013","id":1006013,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"双宫茧桑蚕丝被 空调被","picUrl":"http://yanxuan.nosdn.127.net/583812520c68ca7995b6fac4c67ae2c7.png","retailPrice":699.00,"shareUrl":"","sort":7,"unit":"件","updateTime":"2021-08-08 11:19:36","virtualSales":10},{"actualSales":1,"brandId":1001045,"brief":"双层子母被，四季皆可使用","categoryId":1008008,"counterPrice":14199.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1006014","id":1006014,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"双宫茧桑蚕丝被 子母被","picUrl":"http://yanxuan.nosdn.127.net/2b537159f0f789034bf8c4b339c43750.png","retailPrice":1399.00,"shareUrl":"","sort":15,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":1001000,"brief":"加大加厚，双色精彩","categoryId":1036000,"counterPrice":219.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1011004","id":1011004,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"色织精梳AB纱格纹空调被","picUrl":"http://yanxuan.nosdn.127.net/0984c9388a2c3fd2335779da904be393.png","retailPrice":199.00,"shareUrl":"","sort":2,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":0,"brief":"共享亲密2人时光","categoryId":1008008,"counterPrice":219.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1019002","id":1019002,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"升级款护颈双人记忆枕","picUrl":"http://yanxuan.nosdn.127.net/0118039f7cda342651595d994ed09567.png","retailPrice":199.00,"shareUrl":"","sort":10,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":0,"brief":"健康保护枕","categoryId":1008008,"counterPrice":119.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1019006","id":1019006,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"植物填充护颈夜交藤枕","picUrl":"http://yanxuan.nosdn.127.net/60c3707837c97a21715ecc3986a744ce.png","retailPrice":99.00,"shareUrl":"","sort":7,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":0,"brief":"厚实舒适","categoryId":1008001,"counterPrice":59.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1021000","id":1021000,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"被","name":"埃及进口长绒棉毛巾","picUrl":"http://yanxuan.nosdn.127.net/7191f2599c7fe44ed4cff7a76e853154.png","retailPrice":39.00,"shareUrl":"","sort":7,"unit":"条","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":6,"brandId":1001020,"brief":"浪漫毛线绣球，简约而不简单","categoryId":1008009,"counterPrice":319.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1022000","id":1022000,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"意式毛线绣球四件套","picUrl":"http://yanxuan.nosdn.127.net/5350e35e6f22165f38928f3c2c52ac57.png","retailPrice":299.00,"shareUrl":"","sort":18,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":32,"brandId":1001000,"brief":"柔软纱布，婴童可用","categoryId":1036000,"counterPrice":269.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1027004","id":1027004,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"色织六层纱布夏凉被","picUrl":"http://yanxuan.nosdn.127.net/6252f53aaf36c072b6678f3d8c635132.png","retailPrice":249.00,"shareUrl":"","sort":3,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":32,"brandId":0,"brief":"原生苦荞，健康护颈","categoryId":1008008,"counterPrice":119.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1036002","id":1036002,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"高山苦荞麦枕","picUrl":"http://yanxuan.nosdn.127.net/ffd7efe9d5225dff9f36d5110b027caa.png","retailPrice":99.00,"shareUrl":"","sort":5,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10},{"actualSales":32,"brandId":0,"brief":"5cm记忆绵的亲密包裹","categoryId":1008008,"counterPrice":619.00,"createTime":"2018-02-01 00:00:00","delFlag":false,"goodsSn":"1037011","id":1037011,"isHot":true,"isNew":false,"isOnSale":true,"keywords":"","name":"安睡慢回弹记忆绵床垫","picUrl":"http://yanxuan.nosdn.127.net/a03ea6f4509439acdafcb7ceba1debe0.png","retailPrice":599.00,"shareUrl":"","sort":22,"unit":"件","updateTime":"2018-02-01 00:00:00","virtualSales":10}]}]
    2022-11-27 21:29:48.336 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage_mpCount:137 debug - ==>  Preparing: SELECT COUNT(*) AS total FROM shop_goods WHERE del_flag = 0 AND is_on_sale = 1
    2022-11-27 21:29:48.387 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage_mpCount:137 debug - ==> Parameters: 
    2022-11-27 21:29:48.426 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage_mpCount:137 debug - <==      Total: 1
    2022-11-27 21:29:48.430 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage:137 debug - ==>  Preparing: select id, goods_sn, name, pic_url, counter_price, retail_price, actual_sales, virtual_sales from shop_goods WHERE del_flag = 0 and is_on_sale = 1 order by create_time desc LIMIT ?
    2022-11-27 21:29:48.452 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage:137 debug - ==> Parameters: 6(Long)
    2022-11-27 21:29:48.476 [9d919fb6d33c4652ba28ff87ae210809_12] [http-nio-82-exec-3] [DEBUG] c.w.c.c.m.s.G.selectGoodsListPage:137 debug - <==      Total: 6
    复制代码

最后分析上诉日志：通过`86c76336100c414dbe9217aeb099ccd5`实现接口调用追踪，通过`12`用户ID，实现用户调用追踪

## 七. alibaba excel导出时自定义格式转换优雅实现 ##

官网介绍：`EasyExcel` 是一个基于Java的简单、省内存的读写Excel的开源项目。在尽可能节约内存的情况下支持读写百M的Excel。

`EasyExcel` 是 `alibaba` 出的一个基于 `java poi` 得excel通用处理类库，他的优势在于内存消耗。对比 `easypoi` 方案，`EasyExcel` 在内存消耗、知名度（大厂光环）上更出众些。

博主在使用过程中发现导出excel，官网对自定义格式字段提供了 `converter` 接口，但只简单提供了`CustomStringStringConverter` 类代码，达不到博主想要得优雅要求，如下：

public class CustomStringStringConverter implements Converter<String> {
        @Override
        public Class<?> supportJavaTypeKey() {
            return String.class;
        }
    
        @Override
        public CellDataTypeEnum supportExcelTypeKey() {
            return CellDataTypeEnum.STRING;
        }
    
        /**
         * 这里读的时候会调用
         *
         * @param context
         * @return
         */
        @Override
        public String convertToJavaData(ReadConverterContext<?> context) {
            return "自定义：" + context.getReadCellData().getStringValue();
        }
    
        /**
         * 这里是写的时候会调用 不用管
         *
         * @return
         */
        @Override
        public WriteCellData<?> convertToExcelData(WriteConverterContext<String> context) {
            return new WriteCellData<>(context.getValue());
        }
    
    }
    复制代码

在以上代码中，打个比方想要实现性别字段得自定义格式转换，就需要在convertToExcelData方法中，添加如下代码

@Override
    public WriteCellData<?> convertToExcelData(WriteConverterContext<String> context) {
        String value = context.getValue();
        if ("man".equals(value)) {
            return new WriteCellData<>("男");
        } else {
            return new WriteCellData<>("女");
        }
    }
    复制代码

可以看到，非常得不优雅，对于这种类型字段，博主习惯使用枚举类来定义字段所有类型，然后将枚举类转换为 `map(value,desc)` 结构，就可以优雅得实现这个自定义格式得需求

/**
     * 一、先定义int字段抽象转换类，实现通用转换逻辑
     */
    public abstract class AbstractIntConverter implements Converter<Integer> {
        abstract List<ConverterDTO> getArr();
    
        public WriteCellData<?> convertToExcelData(Integer value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration) {
            List<ConverterDTO> values = getArr();
            Map<Integer, String> map = values.stream().collect(toMap(ConverterDTO::getType, ConverterDTO::getDesc));
            String result = map.getOrDefault(value, "");
            return new WriteCellData<>(result);
        }
    
        static class ConverterDTO {
            private Integer type;
            private String desc;
    
            public Integer getType() {
                return type;
            }
    
            public void setType(Integer type) {
                this.type = type;
            }
    
            public String getDesc() {
                return desc;
            }
    
            public void setDesc(String desc) {
                this.desc = desc;
            }
    
            public ConverterDTO(Integer type, String desc) {
                this.type = type;
                this.desc = desc;
            }
        }
    }
    
    /**
     * 二、定义通用状态字段转换类
     */
    public class StatusConverter extends AbstractIntConverter {
    
        @Override
        List<ConverterDTO> getArr() {
            StatusEnum[] values = StatusEnum.values();
            return Arrays.stream(values).map(sexEnum -> new ConverterDTO(sexEnum.getType(), sexEnum.getDesc())).toList();
        }
    
        /**
         * 状态枚举
         */
        enum StatusEnum {
            MAN(0, "启用"),
            WOMAN(1, "禁用");
    
            private Integer type;
            private String desc;
    
            StatusEnum(Integer type, String desc) {
                this.type = type;
                this.desc = desc;
            }
            public Integer getType() {
                return type;
            }
            public String getDesc() {
                return desc;
            }
        }
    }
    复制代码

最后再导出 `ExcelProperty` 中甜腻加 `StatusConverter` ，就优雅得实现了自定义格式得需求

public class User extends BaseEntity {
        ...
        /**
         * 用户状态 0 启用 1 禁用
         */
        @ExcelProperty(value = "用户状态", converter = StatusConverter.class)
        private Integer userStatus;
        ...
    
    }
    复制代码

## 八. Springboot 默认redis客户端lettuce经常连接超时解决方案 ##

不知道大家有没有遇到这种情况，线上项目使用 `lettuce` 客户端，当操作 `redis` 得接口一段时间没有调用后（比如30分钟），再次调用 `redis` 操作后，就会遇到连接超时得问题，导致接口异常。博主直接给出分析过程：

1.  通过wireshark抓包工具，发现项目中 `redis` 连接创建后，一段时间未传输数据后，客户端发送 `psh` 包，未收到服务端 `ack` 包，触发tcp得超时重传机制，在重传次数重试完后，最终客户端主动关闭了连接。

到这里我们就知道这个问题，主要原因在于服务端没有回复客户端（比如tcp参数设置、防火墙主动关闭等，都是针对一段时间内没有数据传输得tcp连接会做关闭处理），造成了客户端得连接超时

面对这个问题有三种解决方案：

*  redis操作异常后进行重试，这篇文章有介绍 [生产环境Redis连接，长时间无响应被服务器断开问题][Redis]
 *  启用一个心跳定时任务，定时访问 `redis`，保持 `redis` 连接不被关闭，简而言之，就是写一个定时任务，定时调用 `redis`得 `get` 命令，进而保活 `redis` 连接
 *  基于Springboot 提供得 `LettuceClientConfigurationBuilderCustomizer` 自定义客户端配置，博主这里主要针对第三种自定义客户端配置来讲解一种优雅得方式

`Springboot` 项目中关于 `lettuce` 客户端得自动配置是没有启用保活配置得，要启用得话代码如下：

/**
     * 自定义lettuce客户端配置
     *
     * @return LettuceClientConfigurationBuilderCustomizer
     */
    @Bean
    public LettuceClientConfigurationBuilderCustomizer lettuceClientConfigurationBuilderCustomizer() {
        return clientConfigurationBuilder -> {
            LettuceClientConfiguration clientConfiguration = clientConfigurationBuilder.build();
            ClientOptions clientOptions = clientConfiguration.getClientOptions().orElseGet(ClientOptions::create);
            ClientOptions build = clientOptions.mutate().build();
            SocketOptions.KeepAliveOptions.Builder builder = build.getSocketOptions().getKeepAlive().mutate();
            // 保活配置
            builder.enable(true);
            builder.idle(Duration.ofSeconds(30));
            SocketOptions.Builder socketOptionsBuilder = clientOptions.getSocketOptions().mutate();
            SocketOptions.KeepAliveOptions keepAliveOptions = builder.build();
            socketOptionsBuilder.keepAlive(keepAliveOptions);
            SocketOptions socketOptions = socketOptionsBuilder.build();
            ClientOptions clientOptions1 = ClientOptions.builder().socketOptions(socketOptions).build();
            clientConfigurationBuilder.clientOptions(clientOptions1);
        };
    }
    复制代码

添加 `lettuce` 客户端的自定义配置，在 `KeepAliveOptions` 中启用 `enable` ，这样 `lettuce` 客户端就会在tcp协议规范上启用 `keep alive` 机制自动发送心跳包

## 九. redis客户端lettuce启用epoll ##

直接给 [官网连接][Link 1]，配置很简单，添加一个 `netty-all` 得依赖，`lettuce` 会自动检测项目系统是否支持 `epoll`（`linux` 系统支持），并且是否有`netty-transport-native-epoll`依赖（ `netty-all` 包含 `netty-transport-native-epoll` ），都满足得话就会自动启用 `epoll` 事件循环，进一步提升系统性能

<dependency>
        <groupId>io.netty</groupId>
        <artifactId>netty-all</artifactId>
    </dependency>
    复制代码

## 十. Springboot web项目优雅停机 ##

web项目配置了优雅停机后，在重启jar包，或者容器时可以防止正在活动得线程被突然停止（ `kill -9` 无解，请不要使用这个参数杀线上进程，`docker compose` 项目尽量不要用 `docker-compose down` 命令关闭项目，使用 `docker-compose rm -svf` 可以触发优雅停机），造成用户请求失败，在此期间允许完成现有请求但不允许新请求，配置如下：

server: shutdown: "graceful"
    复制代码

## 十一. nginx配置通用请求后缀 ##

先说下这个配置产生得前提，博主公司pc客户项目是基于 `electron` 打包得网页项目，每次项目大版本更新时，为了做好兼容性，防止客户端网页缓存等，会使用一个新网页地址，打个比方：

老网页地址，`v1.1.0` 版本网页访问地址：[api.dev.com/pageV110][api.dev.com_pageV110]

新网页地址，`v1.2.0` 版本网页访问地址：[api.dev.com/pageV120][api.dev.com_pageV120]

那么项目得nginx配置则则需要新加一个 `v1.2.0` 得配置如下：

server {
       listen 80;
       server_name api.dev.com;
       client_max_body_size 10m;
    
       # 老网页v1.1.0配置
       location ~ ^/pageV110 {
                   alias  /home/wwwroot/api.dev.com/pageV110;
                   index  index.html index.htm;
           }
           
       # 新网页v1.2.0配置
       location ~ ^/pageV120 {
                   alias  /home/wwwroot/api.dev.com/pageV120;
                   index  index.html index.htm;
           }
    
    }
    复制代码

那么博主在每次项目发布得时候就需要配合前端发版，配置一个新网页，故产生了这个通用配置得需求，如下：

server {
       listen 80;
       server_name api.dev.com;
       client_max_body_size 10m;
    
       # 配置正则localtion
       location ~ ^/pageV(.*) {
                   set $s $1; # 定义后缀变量
                   alias  /home/wwwroot/api.dev.com/pageV$s;
                   index  index.html index.htm;
           }
    
    }
    复制代码

在 `nginx` 配置文件语法中，`location` 语句可以使用正则表达式，定义 `set $s $1` 变量，实现了通用配置

## 十二. 关于开发人员的自我提升和突破 ##

博主这里主要总结了四点：

1.  多和他人沟通，沟通能把复杂问题简单化，有时候开发阶段一个需求多问几句，可以减少因为个人理解差异导致的需求不一致问题，进而减少开发时间
2.  建立长短期目标，观看技术视频、书籍给自己充电，比如7天利用业余时间看完一本电子书，三十天从零开始一个新项目等
3.  善于总结，对于项目中的疑难bug，踩坑点要有记录，防止下次遇到再掉坑里
4.  敢于尝试、担责，对项目、代码里明确不合理的地方要敢于跟他人沟通，修改问题代码，达到优化目的。对于自己造成的问题要承担，不要推卸责任。对于线上问题要重视，优先解决线上问题。

[045025d22aec430d92262aa50ab972df.webp]: https://img-blog.csdnimg.cn/045025d22aec430d92262aa50ab972df.webp
[Redis]: https://juejin.cn/post/7084648654975270920
[Link 1]: https://link.juejin.cn?target=https%3A%2F%2Flettuce.io%2Fcore%2Frelease%2Freference%2F%23native-transports
[api.dev.com_pageV110]: https://link.juejin.cn?target=http%3A%2F%2Fapi.dev.com%2FpageV110
[api.dev.com_pageV120]: https://link.juejin.cn?target=http%3A%2F%2Fapi.dev.com%2FpageV120