直接看代碼示例
package com.book.java7.concurrency;
import java.time.LocalDate;
import java.util.concurrent.TimeUnit;
/** *//**
* {@link InheritableThreadLocal}示例
*
* <pre>
* public class InheritableThreadLocal<T> extends ThreadLocal<T> {
* protected T childValue(T parentValue) {
* return parentValue;
* }
* </pre>
*
* <pre>
* childValue方法是在子線程初始化時(shí)調(diào)用的，可(Thread.dump).將【子線程-childValue】和date綁定.
* 子線程調(diào)用date.get時(shí)， 會取到子線程初始化時(shí)放到ThreadLocalMap的值.
* </pre>
*
* <p>
* landon認(rèn)為其實(shí)是用線程局部變量這個(gè)類更多的原因可能在于為了隱藏線程內(nèi)部的一些實(shí)現(xiàn)細(xì)節(jié)，使用戶外部調(diào)用更簡單，完全不必理會線程內(nèi)部的一些東西！
*
* @author landon
*
*/
public class InheritableThreadLocalExample 
{
private static class Task implements Runnable {
// InheritableThreadLocal局部變量
private static InheritableThreadLocal<LocalDate> date = new InheritableThreadLocal<LocalDate>() {
// 初始化
protected LocalDate initialValue() {
return LocalDate.now();
}
// 首先輸出繼承的值.然后改變子線程局部變量的值(加了一天)
protected LocalDate childValue(LocalDate parentValue) {
// Thread.dumpStack();
System.out.println(String.format("call childValue Thread:%s,parentValue:%s", Thread.currentThread()
.getName(), parentValue));
return parentValue.plusDays(1);
}
};
@Override
public void run() {
System.out.println(String.format("%s:task begin.date:%s", Thread.currentThread().getName(), date.get()));
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
// 創(chuàng)建一個(gè)子線程
// 從輸出可以看到:此時(shí)輸出的是childValue改變后的值
Thread subThread = new Thread(Thread.currentThread().getName() + "-sub") {
@Override
public void run() {
System.out.println(String.format("%s:task execute.date:%s", Thread.currentThread().getName(),
date.get()));
}
};
subThread.start();
System.out.println(String.format("%s:task end.date:%s", Thread.currentThread().getName(), date.get()));
}
}
public static void main(String[] args) throws Exception {
Task task = new Task();
for (int i = 0; i < 3; i++) {
Thread t = new Thread(task, "Main-Sub-" + i);
t.start();
Thread.sleep(1000);
}
}
}
posted on 2014-11-25 16:22
landon 閱讀(6148)
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