类ThreadLocal的使用
主要解决的是每个线程绑定自己的值，可以将ThreadLocal类比喻成全局存放数据的盒子，盒子中可以存储每个线程私有数据。
类ThreadLocal解决的是变量在不同线程间的隔离线，也就是不同线程拥有自己的值，不同线程中的值是可以放入ThreadLocal类中进行保存的 方法get()与null 复制代码
package Third;
public class Run { public static ThreadLocal tl = new ThreadLocal();
public static void main(String[] args) {
if (tl.get() == null) {
System.out.println("从未放过值");
tl.set("我的值");
}
System.out.println(tl.get());
System.out.println(tl.get());
}
}
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验证线程变量的隔离性 复制代码
package Third;
public class ThreadA extends Thread {
@Override
public void run() {
try {
for (int i = 0; i < 100; i++) {
if (Tools.tl.get() == null) {
Tools.tl.set("ThreadA" + (i + 1));
} else {
System.out.println("ThreadA get Value=" + Tools.tl.get());
}
Thread.sleep(200);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
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package Third;
public class ThreadB extends Thread {
@Override
public void run() {
try {
for (int i = 0; i < 100; i++) {
if (Tools.tl.get() == null) {
Tools.tl.set("ThreadB" + (i + 1));
} else {
System.out.println("ThreadB get Value=" + Tools.tl.get());
}
Thread.sleep(200);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
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package Third;
public class Tools {
public static ThreadLocal tl = new ThreadLocal();
}
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package Third;
public class Run {
public static void main(String[] args) {
try {
ThreadA a = new ThreadA();
ThreadB b = new ThreadB();
a.start();
b.start();
for (int i = 0; i < 100; i++) {
if (Tools.tl.get() == null) {
Tools.tl.set("Main" + (i + 1));
} else {
System.out.println("Main get Value=" + Tools.tl.get());
}
Thread.sleep(200);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
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每个线程取出自己的数据 复制代码
package Third;
import java.util.Date;
public class ThreadA extends Thread {
@Override
public void run() {
try {
for (int i = 0; i < 20; i++) {
if (Tools.tl.get() == null) {
Tools.tl.set(new Date());
}
System.out.println("A " + Tools.tl.get().getTime());
Thread.sleep(100);
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
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package Third;
import java.util.Date;
public class ThreadB extends Thread {
@Override
public void run() {
try {
for (int i = 0; i < 20; i++) {
if (Tools.tl.get() == null) {
Tools.tl.set(new Date());
}
System.out.println("B " + Tools.tl.get().getTime());
Thread.sleep(100);
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
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package Third;
import java.util.Date;
public class Tools {
public static ThreadLocal<Date> tl = new ThreadLocal<Date>();
}
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package Third;
public class Run {
public static void main(String[] args) {
try {
ThreadA a = new ThreadA();
a.start();
Thread.sleep(1000);
ThreadB b = new ThreadB();
b.start();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
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package Third;
public class Tools { public static ThreadLocalExt tl = new ThreadLocalExt(); }
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package Third;
import java.util.Date;
public class ThreadLocalExt extends ThreadLocal { @Override protected Object initialValue() { return new Date().getTime(); } }
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package Third;
public class ThreadA extends Thread {
@Override
public void run() {
try {
for (int i = 0; i < 10; i++) {
System.out.println("在ThreadA线程中取值=" + Tools.tl.get());
Thread.sleep(100);
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
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package Third;
public class Run {
public static void main(String[] args) {
try {
for (int i = 0; i < 10; i++) {
System.out.println(" 在Main线程中取值=" + Tools.tl.get());
Thread.sleep(100);
}
Thread.sleep(5000);
ThreadA a = new ThreadA();
a.start();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
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