关于java:Java-多线程上下文传递在复杂场景下的实践

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一、引言

海内商城从印度做起,缓缓的会有一些其余国家的诉求,这个时候须要咱们针对以后的商城做一个革新,能够撑持多个国家的商城,这里会波及多个问题,多语言,多国家,多时区,本地化等等。在多国家的状况下如何把辨认进去的国家信息传递上来,一层一层直到代码执行的最初一步。甚至还有一些多线程的场景须要解决。

二、背景技术

2.1 ThreadLocal

ThreadLocal 是最容易想到了,入口辨认到国家信息后,丢进 ThreadLocal,这样后续代码、redis、DB 等做国家辨别的时候都能应用到。

这里先简略介绍一下 ThreadLocal:

/**
 * Sets the current thread's copy of this thread-local variable
 * to the specified value.  Most subclasses will have no need to
 * override this method, relying solely on the {@link #initialValue}
 * method to set the values of thread-locals.
 *
 * @param value the value to be stored in the current thread's copy of
 *        this thread-local.
 */
public void set(T value) {Thread t = Thread.currentThread();
    ThreadLocalMap map = getMap(t);
    if (map != null)
        map.set(this, value);
    else
        createMap(t, value);
}
 
 
/**
 * Returns the value in the current thread's copy of this
 * thread-local variable.  If the variable has no value for the
 * current thread, it is first initialized to the value returned
 * by an invocation of the {@link #initialValue} method.
 *
 * @return the current thread's value of this thread-local
 */
public T get() {Thread t = Thread.currentThread();
    ThreadLocalMap map = getMap(t);
    if (map != null) {ThreadLocalMap.Entry e = map.getEntry(this);
        if (e != null) {@SuppressWarnings("unchecked")
            T result = (T)e.value;
            return result;
        }
    }
    return setInitialValue();}
 
 
/**
 * Get the map associated with a ThreadLocal. Overridden in
 * InheritableThreadLocal.
 *
 * @param  t the current thread
 * @return the map
 */
ThreadLocalMap getMap(Thread t) {return t.threadLocals;}
 
 
/**
 * Get the entry associated with key.  This method
 * itself handles only the fast path: a direct hit of existing
 * key. It otherwise relays to getEntryAfterMiss.  This is
 * designed to maximize performance for direct hits, in part
 * by making this method readily inlinable.
 *
 * @param  key the thread local object
 * @return the entry associated with key, or null if no such
 */
private Entry getEntry(ThreadLocal<?> key) {int i = key.threadLocalHashCode & (table.length - 1);
    Entry e = table[i];
    if (e != null && e.get() == key)
        return e;
    else
        return getEntryAfterMiss(key, i, e);
}
  • 每一个 Thread 线程都有属于本人的 threadLocals(ThreadLocalMap), 外面有一个弱援用的 Entry(ThreadLocal,Object)。
  • get 办法首先通过 Thread.currentThread 失去以后线程,而后拿到线程的 threadLocals(ThreadLocalMap),再从 Entry 中获得以后线程存储的 value。
  • set 值的时候更改以后线程的 threadLocals(ThreadLocalMap) 中 Entry 对应的 value 值。

理论应用中除了同步办法之外,还有起异步线程解决的场景,这个时候就须要把 ThreadLocal 的内容从父线程传递给子线程,这个怎么办呢?

不急,Java 还有 InheritableThreadLocal 来帮咱们解决这个问题。

2.2 InheritableThreadLoca


public class InheritableThreadLocal<T> extends ThreadLocal<T> {
    /**
     * Computes the child's initial value for this inheritable thread-local
     * variable as a function of the parent's value at the time the child
     * thread is created.  This method is called from within the parent
     * thread before the child is started.
     * <p>
     * This method merely returns its input argument, and should be overridden
     * if a different behavior is desired.
     *
     * @param parentValue the parent thread's value
     * @return the child thread's initial value
     */
    protected T childValue(T parentValue) {return parentValue;}
 
    /**
     * Get the map associated with a ThreadLocal.
     *
     * @param t the current thread
     */
    ThreadLocalMap getMap(Thread t) {return t.inheritableThreadLocals;}
 
    /**
     * Create the map associated with a ThreadLocal.
     *
     * @param t the current thread
     * @param firstValue value for the initial entry of the table.
     */
    void createMap(Thread t, T firstValue) {t.inheritableThreadLocals = new ThreadLocalMap(this, firstValue);
    }
}
  • java.lang.Thread#init(java.lang.ThreadGroup, java.lang.Runnable, java.lang.String, long, java.security.AccessControlContext, boolean)
if (inheritThreadLocals && parent.inheritableThreadLocals != null)
    this.inheritableThreadLocals =
        ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);
  • InheritableThreadLocal 操作的是 inheritableThreadLocals 这个变量,而不是 ThreadLocal 操作的 threadLocals 变量。
  • 创立新线程的时候会查看父线程中 parent.inheritableThreadLocals 变量是否为 null,如果不为 null 则复制一份 parent.inheritableThreadLocals 的数据到子线程的 this.inheritableThreadLocals 中去。
  • 因为复写了 getMap(Thread) 和 CreateMap() 办法间接操作 inheritableThreadLocals,这样就实现了在子线程中获取父线程 ThreadLocal 值。

当初在应用多线程的时候,都是通过线程池来做的,这个时候用 InheritableThreadLocal 能够吗?会有什么问题吗?先看下上面的代码的执行状况:

  • test
static InheritableThreadLocal<String> inheritableThreadLocal = new InheritableThreadLocal<>();
 
public static void main(String[] args) throws InterruptedException {ExecutorService executorService = Executors.newFixedThreadPool(1);
 
    inheritableThreadLocal.set("i am a inherit parent");
    executorService.execute(new Runnable() {
        @Override
        public void run() {System.out.println(inheritableThreadLocal.get());
        }
    });
 
    TimeUnit.SECONDS.sleep(1);
    inheritableThreadLocal.set("i am a new inherit parent");// 设置新的值
 
    executorService.execute(new Runnable() {
        @Override
        public void run() {System.out.println(inheritableThreadLocal.get());
        }
    });
}
 
 
i am a inherit parent
i am a inherit parent
 
 
public static void main(String[] args) throws InterruptedException {ExecutorService executorService = Executors.newFixedThreadPool(1);
 
    inheritableThreadLocal.set("i am a inherit parent");
    executorService.execute(new Runnable() {
        @Override
        public void run() {System.out.println(inheritableThreadLocal.get());
            inheritableThreadLocal.set("i am a old inherit parent");// 子线程中设置新的值
 
 
        }
    });
 
    TimeUnit.SECONDS.sleep(1);
    inheritableThreadLocal.set("i am a new inherit parent");// 主线程设置新的值
 
    executorService.execute(new Runnable() {
        @Override
        public void run() {System.out.println(inheritableThreadLocal.get());
        }
    });
}
 
 
i am a inherit parent
i am a old inherit parent

这里看第一个执行后果,发现主线程第二次设置的值,没有改掉,还是第一次设置的值“i am a inherit parent”,这是什么起因呢?

再看第二个例子的执行后果,发现在第一个工作中设置的“i am a old inherit parent” 的值,在第二个工作中打印进去了。这又是什么起因呢?

回过头来看看下面的源码,在线程池的状况下,第一次创立线程的时候会从父线程中 copy inheritableThreadLocals 中的数据,所以第一个工作胜利拿到了父线程设置的”i am a inherit parent“,第二个工作执行的时候复用了第一个工作的线程,并不会触发复制父线程中的 inheritableThreadLocals 操作,所以即便在主线程中设置了新的值,也会不失效。同时 get() 办法是间接操作 inheritableThreadLocals 这个变量的,所以就间接拿到了第一个工作设置的值。

那遇到线程池应该怎么办呢?

2.3 TransmittableThreadLocal

TransmittableThreadLocal(TTL)这个时候就派上用场了。这是阿里开源的一个组件,咱们来看看它怎么解决线程池的问题,先来一段代码,在下面的根底上批改一下,应用 TransmittableThreadLocal。


static TransmittableThreadLocal<String> transmittableThreadLocal = new TransmittableThreadLocal<>();// 应用 TransmittableThreadLocal
 
 
public static void main(String[] args) throws InterruptedException {ExecutorService executorService = Executors.newFixedThreadPool(1);
    executorService = TtlExecutors.getTtlExecutorService(executorService); // 用 TtlExecutors 装璜线程池
 
    transmittableThreadLocal.set("i am a transmittable parent");
    executorService.execute(new Runnable() {
        @Override
        public void run() {System.out.println(transmittableThreadLocal.get());
            transmittableThreadLocal.set("i am a old transmittable parent");// 子线程设置新的值
 
        }
    });
    System.out.println(transmittableThreadLocal.get());
 
    TimeUnit.SECONDS.sleep(1);
    transmittableThreadLocal.set("i am a new transmittable parent");// 主线程设置新的值
 
    executorService.execute(new Runnable() {
        @Override
        public void run() {System.out.println(transmittableThreadLocal.get());
        }
    });
}
 
 
i am a transmittable parent
i am a transmittable parent
i am a new transmittable parent

执行代码后发现,应用 TransmittableThreadLocalTtlExecutors.getTtlExecutorService(executorService) 装璜线程池之后,在每次调用工作的时,都会将以后的主线程的 TransmittableThreadLocal 数据 copy 到子线程外面,执行实现后,再革除掉。同时子线程外面的批改回到主线程时其实并没有失效。这样能够保障每次工作执行的时候都是互不干涉的。这是怎么做到的呢?来看源码。

  • TtlExecutors 和 TransmittableThreadLocal 源码

private TtlRunnable(Runnable runnable, boolean releaseTtlValueReferenceAfterRun) {this.capturedRef = new AtomicReference<Object>(capture());
    this.runnable = runnable;
    this.releaseTtlValueReferenceAfterRun = releaseTtlValueReferenceAfterRun;
}
 
com.alibaba.ttl.TtlRunnable#run
/**
 * wrap method {@link Runnable#run()}.
 */
@Override
public void run() {Object captured = capturedRef.get();// 获取线程的 ThreadLocalMap
    if (captured == null || releaseTtlValueReferenceAfterRun && !capturedRef.compareAndSet(captured, null)) {throw new IllegalStateException("TTL value reference is released after run!");
    }
 
    Object backup = replay(captured);// 暂存以后子线程的 ThreadLocalMap 到 backup
    try {runnable.run();
    } finally {restore(backup);// 复原线程执行时被改版的 Threadlocal 对应的值
    }
}
 
 
com.alibaba.ttl.TransmittableThreadLocal.Transmitter#replay
 
 
/**
 * Replay the captured {@link TransmittableThreadLocal} values from {@link #capture()},
 * and return the backup {@link TransmittableThreadLocal} values in current thread before replay.
 *
 * @param captured captured {@link TransmittableThreadLocal} values from other thread from {@link #capture()}
 * @return the backup {@link TransmittableThreadLocal} values before replay
 * @see #capture()
 * @since 2.3.0
 */
public static Object replay(Object captured) {@SuppressWarnings("unchecked")
    Map<TransmittableThreadLocal<?>, Object> capturedMap = (Map<TransmittableThreadLocal<?>, Object>) captured;
    Map<TransmittableThreadLocal<?>, Object> backup = new HashMap<TransmittableThreadLocal<?>, Object>();
 
    for (Iterator<? extends Map.Entry<TransmittableThreadLocal<?>, ?>> iterator = holder.get().entrySet().iterator();
         iterator.hasNext();) {Map.Entry<TransmittableThreadLocal<?>, ?> next = iterator.next();
        TransmittableThreadLocal<?> threadLocal = next.getKey();
 
        // backup
        backup.put(threadLocal, threadLocal.get());
 
        // clear the TTL value only in captured
        // avoid extra TTL value in captured, when run task.
        if (!capturedMap.containsKey(threadLocal)) {iterator.remove();
            threadLocal.superRemove();}
    }
 
    // set value to captured TTL
    for (Map.Entry<TransmittableThreadLocal<?>, Object> entry : capturedMap.entrySet()) {@SuppressWarnings("unchecked")
        TransmittableThreadLocal<Object> threadLocal = (TransmittableThreadLocal<Object>) entry.getKey();
        threadLocal.set(entry.getValue());
    }
 
    // call beforeExecute callback
    doExecuteCallback(true);
 
    return backup;
}
 
 
 
com.alibaba.ttl.TransmittableThreadLocal.Transmitter#restore
 
/**
 * Restore the backup {@link TransmittableThreadLocal} values from {@link Transmitter#replay(Object)}.
 *
 * @param backup the backup {@link TransmittableThreadLocal} values from {@link Transmitter#replay(Object)}
 * @since 2.3.0
 */
public static void restore(Object backup) {@SuppressWarnings("unchecked")
    Map<TransmittableThreadLocal<?>, Object> backupMap = (Map<TransmittableThreadLocal<?>, Object>) backup;
    // call afterExecute callback
    doExecuteCallback(false);
 
    for (Iterator<? extends Map.Entry<TransmittableThreadLocal<?>, ?>> iterator = holder.get().entrySet().iterator();
         iterator.hasNext();) {Map.Entry<TransmittableThreadLocal<?>, ?> next = iterator.next();
        TransmittableThreadLocal<?> threadLocal = next.getKey();
 
        // clear the TTL value only in backup
        // avoid the extra value of backup after restore
        if (!backupMap.containsKey(threadLocal)) {iterator.remove();
            threadLocal.superRemove();}
    }
 
    // restore TTL value
    for (Map.Entry<TransmittableThreadLocal<?>, Object> entry : backupMap.entrySet()) {@SuppressWarnings("unchecked")
        TransmittableThreadLocal<Object> threadLocal = (TransmittableThreadLocal<Object>) entry.getKey();
        threadLocal.set(entry.getValue());
    }
}

能够看下整个过程的残缺时序图:

OK,既然问题都解决了,来看看理论应用吧,有两种应用,先看第一种,波及 HTTP 申请、Dubbo 申请和 job,采纳的是数据级别的隔离。

三、TTL 在海内商城的理论利用

3.1 不分库,分数据行 + SpringMVC

用户 HTTP 申请,首先咱们要从 url 或者 cookie 中解析出国家编号,而后在 TransmittableThreadLocal 中寄存国家信息,在 MyBatis 的拦截器中读取国家数据,进行 sql 革新,最终操作指定的国家数据,多线程场景下用 TtlExecutors 包装原有自定义线程池,保障在应用线程池的时候可能正确将国家信息传递上来。

  •  HTTP 申请

public class ShopShardingHelperUtil {private static TransmittableThreadLocal<String> countrySet = new TransmittableThreadLocal<>();
 
    /**
     * 获取 threadLocal 中设置的国家标记
     * @return
     */
    public static String getCountry() {return countrySet.get();
    }
 
    /**
     * 设置 threadLocal 中设置的国家
     */
    public static void setCountry (String country) {countrySet.set(country.toLowerCase());
    }
 
 
    /**
     * 革除标记
     */
    public static void clear () {countrySet.remove();
    }
}
 
 
 
/** 拦截器对 cookie 和 url 综合判断国家信息,放入到 TransmittableThreadLocal 中 **/
// 设置线程中的国家标记
String country = localeContext.getLocale().getCountry().toLowerCase();
 
ShopShardingHelperUtil.setCountry(country);
 
 
/** 自定义线程池,用 TtlExecutors 包装原有自定义线程池 **/
public static Executor getExecutor() {if (executor == null) {synchronized (TransmittableExecutor.class) {if (executor == null) {executor = TtlExecutors.getTtlExecutor(initExecutor());// 用 TtlExecutors 装璜 Executor,联合 TransmittableThreadLocal 解决异步线程 threadlocal 传递问题
            }
        }
    }
 
    return executor;
}
 
 
/** 理论应用线程池的中央, 间接调用执行即可 **/
TransmittableExecutor.getExecutor().execute(new BatchExeRunnable(param1,param2));
 
 
 
/** mybatis 的 Interceptor 代码, 应用 TransmittableThreadLocal 的国家信息,革新原有 sql,加上国家参数,在增删改查 sql 中辨别国家数据 **/
public Object intercept(Invocation invocation) throws Throwable {StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
    BoundSql boundSql = statementHandler.getBoundSql();
 
    String originalSql = boundSql.getSql();
 
    Statement statement = (Statement) CCJSqlParserUtil.parse(originalSql);
 
    String threadCountry = ShopShardingHelperUtil.getCountry();
 
    // 线程中的国家不为空才进行解决
    if (StringUtils.isNotBlank(threadCountry)) {if (statement instanceof Select) {Select selectStatement = (Select) statement;
            VivoSelectVisitor vivoSelectVisitor = new VivoSelectVisitor(threadCountry);
            vivoSelectVisitor.init(selectStatement);
        } else if (statement instanceof Insert) {Insert insertStatement = (Insert) statement;
            VivoInsertVisitor vivoInsertVisitor = new VivoInsertVisitor(threadCountry);
            vivoInsertVisitor.init(insertStatement);
 
        } else if (statement instanceof Update) {Update updateStatement = (Update) statement;
            VivoUpdateVisitor vivoUpdateVisitor = new VivoUpdateVisitor(threadCountry);
            vivoUpdateVisitor.init(updateStatement);
 
        } else if (statement instanceof Delete) {Delete deleteStatement = (Delete) statement;
            VivoDeleteVisitor vivoDeleteVisitor = new VivoDeleteVisitor(threadCountry);
            vivoDeleteVisitor.init(deleteStatement);
        }
 
 
        Field boundSqlField = BoundSql.class.getDeclaredField("sql");
        boundSqlField.setAccessible(true);
        boundSqlField.set(boundSql, statement.toString());
    } else {logger.error("----------- intercept not-add-country sql.... ---------" + statement.toString());
    }
 
    logger.info("----------- intercept query new sql.... ---------" + statement.toString());
    // 调用办法,实际上就是拦挡的办法
    Object result = invocation.proceed();
 
    return result;
}

对于 Dubbo 接口和无奈判断国家信息的 HTTP 接口,在入参局部减少国家信息参数,通过拦截器或者手动 set 国家信息到 TransmittableThreadLocal。

对于定时工作 job,因为所有国家都须要执行,所以会把所有国家进行遍历执行,这也能够通过简略的注解来解决。

这个版本的革新,点检测试也根本通过了,自动化脚本验证也是没问题的,不过因为业务倒退问题最终没上线。

3.2 分库 + SpringBoot

后续在建设新的国家商城的时候,分库分表计划调整为每个国家独立数据库,同时整体开发框架降级到 SpringBoot,咱们把这套计划做了降级,总体思路是一样的,只是在实现细节上略有不同。

SpringBoot 外面的异步个别通过 @Async 这个注解来实现,通过自定义线程池来包装,应用时在 HTTP 申请判断 locale 信息的写入国家信息,后续实现切 DB 的操作。

对于 Dubbo 接口和无奈判断国家信息的 HTTP 接口,在入参局部减少国家信息参数,通过拦截器或者手动 set 国家信息到 TransmittableThreadLocal。


@Bean
public ThreadPoolTaskExecutor threadPoolTaskExecutor(){return TtlThreadPoolExecutors.getAsyncExecutor();
}
 
 
public class TtlThreadPoolExecutors {
 
    private static final String COMMON_BUSINESS = "COMMON_EXECUTOR";
 
    public static final int QUEUE_CAPACITY = 20000;
 
    public static ExecutorService getExecutorService() {return TtlExecutorServiceMananger.getExecutorService(COMMON_BUSINESS);
    }
 
    public static ExecutorService getExecutorService(String threadGroupName) {return TtlExecutorServiceMananger.getExecutorService(threadGroupName);
    }
 
    public static ThreadPoolTaskExecutor getAsyncExecutor() {
        // 用 TtlExecutors 装璜 Executor,联合 TransmittableThreadLocal 解决异步线程 threadlocal 传递问题
        return getTtlThreadPoolTaskExecutor(initTaskExecutor());
    }
 
    private static ThreadPoolTaskExecutor initTaskExecutor () {return initTaskExecutor(TtlThreadPoolFactory.DEFAULT_CORE_SIZE, TtlThreadPoolFactory.DEFAULT_POOL_SIZE, QUEUE_CAPACITY);
    }
 
    private static ThreadPoolTaskExecutor initTaskExecutor (int coreSize, int poolSize, int executorQueueCapacity) {ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        taskExecutor.setCorePoolSize(coreSize);
        taskExecutor.setMaxPoolSize(poolSize);
        taskExecutor.setQueueCapacity(executorQueueCapacity);
        taskExecutor.setKeepAliveSeconds(120);
        taskExecutor.setAllowCoreThreadTimeOut(true);
        taskExecutor.setThreadNamePrefix("TaskExecutor-ttl");
        taskExecutor.initialize();
        return taskExecutor;
    }
 
    private static ThreadPoolTaskExecutor getTtlThreadPoolTaskExecutor(ThreadPoolTaskExecutor executor) {if (null == executor || executor instanceof ThreadPoolTaskExecutorWrapper) {return executor;}
        return new ThreadPoolTaskExecutorWrapper(executor);
    }
}
 
 
 
 
/**
 * @ClassName : LocaleContextHolder
 * @Description : 本地化信息上下文 holder
 */
public class LocalizationContextHolder {private static TransmittableThreadLocal<LocalizationContext> localizationContextHolder = new TransmittableThreadLocal<>();
    private static LocalizationInfo defaultLocalizationInfo = new LocalizationInfo();
 
    private LocalizationContextHolder(){}
 
    public static LocalizationContext getLocalizationContext() {return localizationContextHolder.get();
    }
 
    public static void resetLocalizationContext () {localizationContextHolder.remove();
    }
 
    public static void setLocalizationContext (LocalizationContext localizationContext) {if(localizationContext == null) {resetLocalizationContext();
        } else {localizationContextHolder.set(localizationContext);
        }
    }
 
    public static void setLocalizationInfo (LocalizationInfo localizationInfo) {LocalizationContext localizationContext = getLocalizationContext();
        String brand = (localizationContext instanceof BrandLocalizationContext ?
                ((BrandLocalizationContext) localizationContext).getBrand() : null);
        if(StringUtils.isNotEmpty(brand)) {localizationContext = new SimpleBrandLocalizationContext(localizationInfo, brand);
        } else if(localizationInfo != null) {localizationContext = new SimpleLocalizationContext(localizationInfo);
        } else {localizationContext = null;}
        setLocalizationContext(localizationContext);
    }
 
    public static void setDefaultLocalizationInfo(@Nullable LocalizationInfo localizationInfo) {LocalizationContextHolder.defaultLocalizationInfo = localizationInfo;}
 
    public static LocalizationInfo getLocalizationInfo () {LocalizationContext localizationContext = getLocalizationContext();
        if(localizationContext != null) {LocalizationInfo localizationInfo = localizationContext.getLocalizationInfo();
            if(localizationInfo != null) {return localizationInfo;}
        }
        return defaultLocalizationInfo;
    }
 
    public static String getCountry(){return getLocalizationInfo().getCountry();}
 
    public static String getTimezone(){return getLocalizationInfo().getTimezone();}
 
    public static String getBrand(){return getBrand(getLocalizationContext());
    }
 
    public static String getBrand(LocalizationContext localizationContext) {if(localizationContext == null) {return null;}
        if(localizationContext instanceof BrandLocalizationContext) {return ((BrandLocalizationContext) localizationContext).getBrand();}
        throw new LocaleException("unsupported localizationContext type");
    }
}
    @Override
    public LocaleContext resolveLocaleContext(final HttpServletRequest request) {parseLocaleCookieIfNecessary(request);
        LocaleContext localeContext = new TimeZoneAwareLocaleContext() {
            @Override
            public Locale getLocale() {return (Locale) request.getAttribute(LOCALE_REQUEST_ATTRIBUTE_NAME);
            }
            @Override
            public TimeZone getTimeZone() {return (TimeZone) request.getAttribute(TIME_ZONE_REQUEST_ATTRIBUTE_NAME);
            }
        };
        // 设置线程中的国家标记
        setLocalizationInfo(request, localeContext.getLocale());
        return localeContext;
    }
 
    private void setLocalizationInfo(HttpServletRequest request, Locale locale) {String country = locale!=null?locale.getCountry():null;
        String language = locale!=null?(locale.getLanguage() + "_" + locale.getVariant()):null;
        LocaleRequestMessage localeRequestMessage = localeRequestParser.parse(request);
        final String countryStr = country;
        final String languageStr = language;
        final String brandStr = localeRequestMessage.getBrand();
        LocalizationContextHolder.setLocalizationContext(new BrandLocalizationContext() {
            @Override
            public String getBrand() {return brandStr;}
 
            @Override
            public LocalizationInfo getLocalizationInfo() {return LocalizationInfoAssembler.assemble(countryStr, languageStr);
            }
        });
    }

对于定时工作 job,因为所有国家都须要执行,所以会把所有国家进行遍历执行,这也能够通过简略的注解和 AOP 来解决。

四、总结

本文从业务拓展的角度论述了在简单业务场景下如何通过 ThreadLocal,过渡到 InheritableThreadLocal,再通过 TransmittableThreadLocal 解决理论业务问题。因为海内的业务在一直的摸索中后退,技术也在一直的摸索中演进,面对这种复杂多变的状况,咱们的应答策略是先做国际化,再做本地化,more global 能力 more local,多国家的隔离只是国际化最根本的终点,将来还有很多业务和技术等着咱们去挑战。

作者:vivo 官网商城开发团队

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