public class Main {
private static final String KEY = "requestId";
private static final Logger logger = LoggerFactory.getLogger(Main.class);
public static void main(String[] args) {
// 入口传入请求ID
MDC.put(KEY, UUID.randomUUID().toString());
// 打印日志
logger.debug("log in main thread 1");
logger.debug("log in main thread 2");
logger.debug("log in main thread 3");
// 出口移除请求ID
MDC.remove(KEY);
}
}
public class MDCRunnable implements Runnable {
private final Runnable runnable;
private final Map<String, String> map;
public MDCRunnable(Runnable runnable) {
this.runnable = runnable;
// 保存当前线程的MDC值
this.map = MDC.getCopyOfContextMap();
}
@Override
public void run() {
// 传入已保存的MDC值
for (Map.Entry<String, String> entry : map.entrySet()) {
MDC.put(entry.getKey(), entry.getValue());
}
// 装饰器模式，执行run方法
runnable.run();
// 移除已保存的MDC值
for (Map.Entry<String, String> entry : map.entrySet()) {
MDC.remove(entry.getKey());
}
}
}
接着，我们需要对main函数里创建的Runnable实现类进行装饰：
java复制代码
public class Main {
private static final String KEY = "requestId";
private static final Logger logger = LoggerFactory.getLogger(Main.class);
private static final ExecutorService EXECUTOR = Executors.newSingleThreadExecutor();
public static void main(String[] args) {
// 入口传入请求ID
MDC.put(KEY, UUID.randomUUID().toString());
// 主线程打印<font style="color: #1e6bb8;word-wrap: break-word;font-weight: bold;border-bottom: 1px solid">日志</font>
logger.debug("log in main thread");
// 异步线程打印<font style="color: #1e6bb8;word-wrap: break-word;font-weight: bold;border-bottom: 1px solid">日志</font>，用MDCRunnable装饰Runnable
new Thread(new MDCRunnable(new Runnable() {
@Override
public void run() {
logger.debug("log in other thread");
}
})).start();
// 异步线程池打印日志，用MDCRunnable装饰Runnable
EXECUTOR.execute(new MDCRunnable(new Runnable() {
@Override
public void run() {
logger.debug("log in other thread pool");
}
}));
EXECUTOR.shutdown();
// 出口移除请求ID
MDC.remove(KEY);
}
}
执行main函数，将会输出以下日志 ：
java复制代码
2018-03-04 23:44:05.343 {requestId=5ee2a117-e090-41d8-977b-cef5dea09d34} [main] DEBUG cn.wudashan.Main - log in main thread
2018-03-04 23:44:05.346 {requestId=5ee2a117-e090-41d8-977b-cef5dea09d34} [Thread-1] DEBUG cn.wudashan.Main - log in other thread
2018-03-04 23:44:05.347 {requestId=5ee2a117-e090-41d8-977b-cef5dea09d34} [pool-2-thread-1] DEBUG cn.wudashan.Main - log in other thread pool
