关于java:十二条后端开发经验分享纯干货

本文是博主从事后端开发以来，对公司、集体我的项目的经验总结，蕴含代码编写、性能举荐、第三方库应用及优雅配置等，心愿大家看到都能有所播种

博主 github 地址: https://github.com/wayn111

在 Java 开发中，线程池的应用必不可少，应用无返回值 execute() 办法时，线程执行产生异样的话，须要记录日志，不便回溯，个别做法是在线程执行办法内 try/catch 解决，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;
        }
    });
}

然而当线程池调用办法很多时，那么每个线程执行办法内都要 try/catch 解决，这就不优雅了，其实 ThreadPoolExecutor 类还反对传入 ThreadFactory 参数，自定义线程工厂，在创立 thread 时，指定 setUncaughtExceptionHandler 异样解决办法，这样就能够做到全局解决异样了，代码如下：

ThreadFactory threadFactory = r -> {Thread thread = new Thread(r);
    thread.setUncaughtExceptionHandler((t, e) -> {
        // 记录线程异样
        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;
});

先介绍下线程池得四种决绝策略

AbortPolicy：抛弃工作并抛出 RejectedExecutionException 异样，这是线程池默认的回绝策略
DiscardPolicy：抛弃工作，然而不抛出异样。如果线程队列已满，则后续提交的工作都会被抛弃，且是静默抛弃。
应用此策略，可能会使咱们无奈发现零碎的异样状态。倡议是一些无关紧要的业务采纳此策略
DiscardOldestPolicy：抛弃队列最后面的工作，而后从新提交被回绝的工作。此回绝策略，是一种喜新厌旧的回绝策略。是否要采纳此种回绝策略，还得依据理论业务是否容许抛弃老工作来认真掂量。
CallerRunsPolicy：由调用线程解决该工作

如下是一个线上业务接口应用得线程池配置，决绝策略采纳 CallerRunsPolicy

// 某个线上线程池配置如下
ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
                50, // 最小外围线程数
                50, // 最大线程数，当队列满时，能创立的最大线程数
                60L, TimeUnit.SECONDS, // 闲暇线程超过外围线程时，回收该线程的最大等待时间
                new LinkedBlockingQueue<>(5000), // 阻塞队列大小, 当外围线程应用满时，新的线程会放进队列
            new CustomizableThreadFactory("task"), // 自定义线程名
                new ThreadPoolExecutor.CallerRunsPolicy() // 线程执行的回绝策略);

在某些状况下，子线程工作调用第三方接口超时，导致外围线程数、最大线程数占满、阻塞队列占满的状况下执行回绝策略时，因为应用 CallerRunsPolicy 策略，导致业务线程执行子工作时持续超时，进而导致接口执行异样，这种状况下，思考到子线程工作得重要性，不是很重要得话，能够应用 DiscardPolicy 策略，要是很重要，能够发送到音讯队列中长久化子线程工作数据待后续解决

博主举荐通过动态外部类实现单例模式，并实现懒加载成果，代码如下

// 应用动态外部类实现单例模式封装，防止线程平安问题，防止反复初始化成员属性  
@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  
    {  
    
        // 在代码块中实现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 汇合中  
            IoUtil.readUtf8Lines(resourceAsStream, strings);  
        } catch (IOException e) {log.error(e.getMessage(), e);  
        }  
    }  
  
    public static FilterIpUtil getInstance() {return InnerClassInstance.instance;}  
    // 应用外部类实现单例模式，由 jvm 保障线程平安  
    private static class InnerClassInstance {private static final FilterIpUtil instance = new FilterIpUtil();  
    }  
  
    // 判断汇合中是否蕴含指标参数  
    public boolean isFilter(String arg) {return strings.contains(arg);  
    }  
  
}

在博主之前公司得我的项目中，ip 解析是调用淘宝 IP 还有聚合 IP 接口获取后果，通常耗时 200 毫秒左右，并且接口不稳固时而会挂。都会影响业务接口耗时，起初在 github 上理解到 ip2region 这个我的项目，应用本地 ip 库查问，查问速度微秒级别，精准度能达到 90%，然而 ip 库还是有少部分 ip 信息不准，倡议数据库中把申请 ip 地址保留下来。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 微秒级别的查问效率，提供了泛滥支流编程语言的 xdb 数据生成和查问客户端实现基于 xdb 文件的查问，上面是一个 Spring 我的项目中 ip2region 帮忙类来实现 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、查问
        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、敞开资源 - 该 searcher 对象能够平安用于并发，等整个服务敞开的时候再敞开 searcher
        // searcher.close();

        // 备注：并发应用，用整个 xdb 数据缓存创立的查问对象能够平安的用于并发，也就是你能够把这个 searcher 对象做成全局对象去跨线程拜访。return null;
    }
}

要留神得就是 ip2region v2.0 版本应用的 xdb 文件不倡议放在我的项目 resources 下一起打包，存在编码格局问题，倡议通过指定门路加载得形式独自放在服务器目录下

Springboot + mybatis 得我的项目中个别通过 @MapperScan 注解配置 dao 层包目录，来实现 dao 层加强，其实我的项目中配置一个 @MapperScan 是指定一个数据源，配置两个@MapperScan 就能够指定两个数据源，通过不同得 dao 层包目录辨别，来实现不同数据源得拜访隔离。

比方上面代码中，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，这个形式比网上得基于 aop 加注解得形式更加简洁好用，也没有单个办法中应用不同数据源切换得问题，因而举荐这种写法

/**
 * 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 配置胜利");
        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 配置胜利");
        return sessionFactoryBean.getObject();}
}

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:

博主刚开始编码一、两年得时候一个我的项目中遇到了多数据源应用得问题，那时候题主便在网上搜寻 Spring 多数据源 得帖子，大多数都是基于 Spring 提供得AbstractRoutingDataSource + AOP + 注解 来做动静切换，包含当初风行得 Mybatis plus 官网得多数据源解决方案也是这种做法，这种做法解决了博主过后得多数据源应用问题，起初加了一个需要，在一个定时工作中，查问两个数据源得数据，才发现动静切换在单个办法中不好用了，最初应用得原生 jdbc 数据源解决。多年后，博主在另一家公司得我的项目中又遇到了多数据源问题，然而这次博主在网上搜寻得是Mybatis 多数据源，才发现了这个优雅得解决方案，进而举荐给大家

MDC 介绍

MDC(Mapped Diagnostic Context，映射调试上下文)是 log4j、logback 及 log4j2 提供的一种不便在多线程条件下记录日志的性能。MDC 能够看成是一个 与以后线程绑定的哈希表 ，能够往其中增加键值对。MDC 中蕴含的内容能够 被同一线程中执行的代码所拜访。以后线程的子线程会继承其父线程中的 MDC 的内容。当须要记录日志时，只须要从 MDC 中获取所需的信息即可。

尽管 MDC 可能不便得实现接口申请调用追踪性能，然而它在子线程中会失落父线程中增加得键值对信息，解决办法是通过父线程中调用线程池前调用 MDC.getCopyOfContextMap()，而后在子线程中第一个调用 MDC.setConextMap() 获取键值对信息，残缺实现代码如下：

/**
 * 自定义 Spring 线程池，解决子线程失落 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 帮忙类，增加 reqest_id
 */
public class ThreadMdcUtil {


    public static final String REQUEST_ID = "request_id";

    /**
     * 设置申请惟一 ID
     */
    public static void setTraceIdIfAbsent() {if (MDC.get(REQUEST_ID) == null) {MDC.put(REQUEST_ID, IdUtil.getUid());
        }
    }

    /**
     * 存在 userId 则增加到 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();
            }
        };
    }
}

在 Spring Security 中增加 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 {
            // 入口传入申请 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 {
            // 进口移除申请 ID
            ThreadMdcUtil.removeTraceId();}
    }

}

最初在 logback.xml 中增加 %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"/>

日志打印成果如下：

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, 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，记录生存","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":" 简洁知性记忆棉坐垫 ","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":" 宫廷豪华真丝四件套 ","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":"自在海军领摸索将来梦","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":"经典海魂纹自在海军领","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":"桌面整顿神器","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，清新柔滑","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，四季皆可应用","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":"共享密切 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":" 降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":"衰弱爱护枕","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":" 动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":"厚实舒服","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，简洁而不简略 ","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，衰弱护颈 ","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":"平地苦荞麦枕","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 记忆绵的密切包裹 ","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

最初剖析上诉日志：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

官网介绍：EasyExcel 是一个基于 Java 的简略、省内存的读写 Excel 的开源我的项目。在尽可能节约内存的状况下反对读写百 M 的 Excel。

EasyExcel 是 alibaba 出的一个基于 java poi 得 excel 通用解决类库，他的劣势在于内存耗费。比照 easypoi 计划，EasyExcel 在内存耗费、知名度（大厂光环）上更出众些。

博主在应用过程中发现导出 excel，官网对自定义格局字段提供了 converter 接口，但只简略提供了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 不必管
     *
     * @return
     */
    @Override
    public WriteCellData<?> convertToExcelData(WriteConverterContext<String> context) {return new WriteCellData<>(context.getValue());
    }

}

在以上代码中，打个比方想要实现性别字段得自定义格局转换，就须要在 convertToExcelData 办法中，增加如下代码

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

能够看到，十分得不优雅，对于这种类型字段，博主习惯应用枚举类来定义字段所有类型，而后将枚举类转换为 map(value,desc) 构造，就能够优雅得实现这个自定义格局得需要

/**
 * 一、先定义 int 字段形象转换类，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;}
    }
}

最初再导出 ExcelProperty 中甜腻加 StatusConverter，就优雅得实现了自定义格局得需要

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;
    ...

}

不晓得大家有没有遇到这种状况，线上我的项目应用 lettuce 客户端，当操作 redis 得接口一段时间没有调用后（比方 30 分钟），再次调用 redis 操作后，就会遇到连贯超时得问题，导致接口异样。博主间接给出剖析过程：

通过 wireshark 抓包工具，发现我的项目中 redis 连贯创立后，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，最终客户端被动敞开了连贯。

到这里咱们就晓得这个问题，次要起因在于服务端没有回复客户端（比方 tcp 参数设置、防火墙被动敞开等，都是针对一段时间内没有数据传输得 tcp 连贯会做敞开解决），造成了客户端得连贯超时

面对这个问题有三种解决方案：

redis 操作异样后进行重试，这篇文章有介绍生产环境 Redis 连贯，长时间无响应被服务器断开问题
启用一个心跳定时工作，定时拜访 redis，放弃 redis 连贯不被敞开，简而言之，就是写一个定时工作，定时调用 redis得 get 命令，进而保活 redis 连贯
基于 Springboot 提供得 LettuceClientConfigurationBuilderCustomizer 自定义客户端配置，博主这里次要针对第三种自定义客户端配置来解说一种优雅得形式

Springboot 我的项目中对于 lettuce 客户端得主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);
    };
}

增加 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 协定标准上启用 keep alive 机制主动发送心跳包

间接给官网连贯，配置很简略，增加一个 netty-all 得依赖，lettuce 会自动检测我的项目零碎是否反对 epoll（linux 零碎反对），并且是否有 netty-transport-native-epoll 依赖（netty-all 蕴含 netty-transport-native-epoll），都满足得话就会主动启用 epoll 事件循环，进一步晋升零碎性能

<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
</dependency>

web 我的项目配置了优雅停机后，在重启 jar 包，或者容器时能够避免正在流动得线程被忽然进行（kill -9 无解，请不要应用这个参数杀线上过程，docker compose 我的项目尽量不要用 docker-compose down 命令敞开我的项目，应用 docker-compose rm -svf 能够触发优雅停机），造成用户申请失败，在此期间容许实现现有申请但不容许新申请，配置如下：

server: shutdown: "graceful"

先说下这个配置产生得前提，博主公司 pc 客户我的项目是基于 electron 打包得网页我的项目，每次我的项目大版本更新时，为了做好兼容性，避免客户端网页缓存等，会应用一个新网页地址，打个比方：

老网页地址，v1.1.0 版本网页拜访地址：http://api.dev.com/pageV110

新网页地址，v1.2.0 版本网页拜访地址：http://api.dev.com/pageV120

那么我的项目得 nginx 配置则则须要新加一个 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;
       }

}

那么博主在每次我的项目公布得时候就须要配合前端发版，配置一个新网页，故产生了这个通用配置得需要，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;
       }

}

在 nginx 配置文件语法中，location 语句能够应用正则表达式，定义 set $s $1 变量，实现了通用配置

博主这里次要总结了四点：

多和别人沟通，沟通能把简单问题简单化，有时候开发阶段一个需要多问几句，能够缩小因为集体了解差别导致的需要不统一问题，进而缩小开发工夫
建设长短期指标，观看技术视频、书籍给本人充电，比方 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我的项目等
长于总结，对于我的项目中的疑难 bug，踩坑点要有记录，避免下次遇到再掉坑里
敢于尝试、担责，对我的项目、代码里明确不合理的中央要敢于跟别人沟通，批改问题代码，达到优化目标。对于本人造成的问题要承当，不要推卸责任。对于线上问题要器重，优先解决线上问题。

关于java:十二条后端开发经验分享纯干货

前言

一. 优雅的进行线程池异样解决

二. 线程池决绝策略设置谬误导致业务接口执行超时

三. 优雅的单例模式懒加载帮忙类代码实现

四. 应用 ip2region 实现申请地址解析

五. 优雅得 Springboot + mybatis 配置多数据源形式

六. Spring Security 我的项目中，应用 MDC 实现接口申请调用追踪，以及用户 ID 记录

MDC 介绍

七. alibaba excel 导出时自定义格局转换优雅实现

八. Springboot 默认 redis 客户端 lettuce 常常连贯超时解决方案

九. redis 客户端 lettuce 启用 epoll

十. Springboot web 我的项目优雅停机

十一. nginx 配置通用申请后缀

十二. 对于开发人员的自我晋升和冲破

Just My Socks（注册教程内含优惠码）

关于java:十二条后端开发经验分享纯干货

前言

一. 优雅的进行线程池异样解决

二. 线程池决绝策略设置谬误导致业务接口执行超时

三. 优雅的单例模式懒加载帮忙类代码实现

四. 应用 ip2region 实现申请地址解析

五. 优雅得 Springboot + mybatis 配置多数据源形式

六. Spring Security 我的项目中，应用 MDC 实现接口申请调用追踪，以及用户 ID 记录

MDC 介绍

七. alibaba excel 导出时自定义格局转换优雅实现

八. Springboot 默认 redis 客户端 lettuce 常常连贯超时解决方案

九. redis 客户端 lettuce 启用 epoll

十. Springboot web 我的项目优雅停机

十一. nginx 配置通用申请后缀

十二. 对于开发人员的自我晋升和冲破

Just My Socks（注册教程 内含优惠码）

Just My Socks（注册教程内含优惠码）