013.多线程-ThreadLocal
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为每一个线程提供一个局部变量。
code of demo:
- 创建三个线程，分别打印递增的IDS
错误demo
package cn.qbz.thread;
/**
* @Author: 花生米
* @Date: 2018/11/16 18:15
*/
public class ThreadLocalTest {
public static void main(String[] args) {
//创建三个线程，每个线程均获得其IDS
Ids ids = new Ids();
GetIds t1 = new GetIds(ids);
GetIds t2 = new GetIds(ids);
GetIds t3 = new GetIds(ids);
t1.start();
t2.start();
t3.start();
}
}
class GetIds extends Thread {
private Ids ids;
public GetIds(Ids ids) {
this.ids = ids;
}
@Override
public void run() {
for (int i = 0; i < 3; i++) {
System.out.println(getName() + "..." + ids.nextId());
}
}
}
class Ids {
private int id = 0;
public int nextId() {
return id++;
}
}
通过创建多个被执行对象来解决
package cn.qbz.thread;
/**
* @Author: 花生米
* @Date: 2018/11/16 18:15
*/
public class ThreadLocalTest {
public static void main(String[] args) {
//创建三个线程，每个线程均获得其IDS
Ids ids1 = new Ids();
Ids ids2 = new Ids();
Ids ids3 = new Ids();
GetIds t1 = new GetIds(ids1);
GetIds t2 = new GetIds(ids2);
GetIds t3 = new GetIds(ids3);
t1.start();
t2.start();
t3.start();
}
}
class GetIds extends Thread {
private Ids ids;
public GetIds(Ids ids) {
this.ids = ids;
}
@Override
public void run() {
for (int i = 0; i < 3; i++) {
System.out.println(getName() + "..." + ids.nextId());
}
}
}
class Ids {
private int id = 0;
public int nextId() {
return id++;
}
}
使用Thread Local包装Ids
package cn.qbz.thread;
/**
* @Author: 花生米
* @Date: 2018/11/16 18:15
*/
public class ThreadLocalTest {
public static void main(String[] args) {
//创建三个线程，每个线程均获得其IDS
Ids ids = new Ids();
GetIds t1 = new GetIds(ids);
GetIds t2 = new GetIds(ids);
GetIds t3 = new GetIds(ids);
t1.start();
t2.start();
t3.start();
}
}
class GetIds extends Thread {
private Ids ids;
public GetIds(Ids ids) {
this.ids = ids;
}
@Override
public void run() {
for (int i = 0; i < 3; i++) {
System.out.println(getName() + "..." + ids.nextId());
}
}
}
class Ids {
ThreadLocal<Integer> threadLocal = ThreadLocal.withInitial(() -> 0);
public int nextId() {
threadLocal.set(threadLocal.get() + 1);
return threadLocal.get();
}
}
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原始发表：2018年11月16日，如有侵权请联系 cloudcommunity@tencent.com 删除
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