Java 中的 Java.util.concurrent.Phaser 类，带示例
原文:https://www . geesforgeks . org/Java-util-concurrent-phaser-class-in-Java-with-examples/
Phaser 的主要目的是实现代表一个或多个活动阶段的线程同步。它允许我们定义一个同步对象，等待一个特定的阶段完成。然后进入下一阶段，直到该阶段结束。它还可以用于同步单个相位，在这方面，它的作用很像 CyclicBarrier。
等级体系
java.lang.Object
? java.util.concurrent
? Class Phaser
语法
public class Phaser
extends Object
施工人员:
- 移相器()–这将创建一个最初注册方为零的移相器。一个线程只能在注册后使用这个相位器。
public Phaser()
- 相位器(int parties)–这创建了一个相位器，需要 parties 数量的线程才能前进到下一个阶段。
public Phaser(int parties)
throws IllegalArgumentException
- 相位器(相位器父级)–这将为新对象指定父级相位器。注册方的数量设置为零。
public Phaser(Phaser parent)
- 相位器(相位器父级，inter parties)–这将为新创建的对象指定一个父级相位器，以及进入下一阶段所需的参与方数量。
public Phaser(Phaser parent, int parties)
throws IllegalArgumentException
示例 1:
注意:输出可能会随着每次运行而变化。
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to show Phaser Class
import java.util.concurrent.Phaser;
// A thread of execution that uses a phaser.
class MyThread implements Runnable {
Phaser phaser;
String title;
public MyThread(Phaser phaser, String title)
{
this.phaser = phaser;
this.title = title;
phaser.register();
new Thread(this).start();
}
@Override public void run()
{
System.out.println("Thread: " + title
+ " Phase Zero Started");
phaser.arriveAndAwaitAdvance();
// Stop execution to prevent jumbled output
try {
Thread.sleep(10);
}
catch (InterruptedException e) {
System.out.println(e);
}
System.out.println("Thread: " + title
+ " Phase One Started");
phaser.arriveAndAwaitAdvance();
// Stop execution to prevent jumbled output
try {
Thread.sleep(10);
}
catch (InterruptedException e) {
System.out.println(e);
}
System.out.println("Thread: " + title
+ " Phase Two Started");
phaser.arriveAndDeregister();
}
}
public class PhaserExample {
public static void main(String[] args)
{
Phaser phaser = new Phaser();
phaser.register();
int currentPhase;
System.out.println("Starting");
new MyThread(phaser, "A");
new MyThread(phaser, "B");
new MyThread(phaser, "C");
// Wait for all threads to complete phase Zero.
currentPhase = phaser.getPhase();
phaser.arriveAndAwaitAdvance();
System.out.println("Phase " + currentPhase
+ " Complete");
System.out.println("Phase Zero Ended");
// Wait for all threads to complete phase One.
currentPhase = phaser.getPhase();
phaser.arriveAndAwaitAdvance();
System.out.println("Phase " + currentPhase
+ " Complete");
System.out.println("Phase One Ended");
currentPhase = phaser.getPhase();
phaser.arriveAndAwaitAdvance();
System.out.println("Phase " + currentPhase
+ " Complete");
System.out.println("Phase Two Ended");
// Deregister the main thread.
phaser.arriveAndDeregister();
if (phaser.isTerminated()) {
System.out.println("Phaser is terminated");
}
}
}
Output
Starting
Thread: B Phase Zero Started
Thread: A Phase Zero Started
Thread: C Phase Zero Started
Thread: A Phase One Started
Thread: B Phase One Started
Thread: C Phase One Started
Phase 0 Complete
Phase Zero Ended
Phase 1 Complete
Phase One Ended
Thread: C Phase Two Started
Thread: A Phase Two Started
Thread: B Phase Two Started
Phase 2 Complete
Phase Two Ended
Phaser is terminated
示例 2:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to show Phaser Class
import java.util.concurrent.Phaser;
// A thread of execution that uses a phaser.
class MyThread implements Runnable {
Phaser phaser;
String title;
public MyThread(Phaser phaser, String title)
{
this.phaser = phaser;
this.title = title;
phaser.register();
new Thread(this).start();
}
@Override public void run()
{
System.out.println("Thread: " + title
+ " Phase Zero Started");
phaser.arriveAndAwaitAdvance();
// Stop execution to prevent jumbled output
try {
Thread.sleep(10);
}
catch (InterruptedException e) {
System.out.println(e);
}
System.out.println("Thread: " + title
+ " Phase One Started");
phaser.arriveAndAwaitAdvance();
// Stop execution to prevent jumbled output
try {
Thread.sleep(10);
}
catch (InterruptedException e) {
System.out.println(e);
}
System.out.println("Thread: " + title
+ " Phase Two Started");
phaser.arriveAndDeregister();
}
}
public class PhaserExample {
public static void main(String[] args)
{
Phaser phaser = new Phaser();
phaser.register();
int currentPhase;
System.out.println("Starting");
new MyThread(phaser, "A");
new MyThread(phaser, "B");
new MyThread(phaser, "C");
// Wait for all threads to complete phase Zero.
currentPhase = phaser.getPhase();
phaser.arriveAndAwaitAdvance();
System.out.println("Phase " + currentPhase
+ " Complete");
System.out.println("Phase Zero Ended");
// Wait for all threads to complete phase One.
currentPhase = phaser.getPhase();
phaser.arriveAndAwaitAdvance();
System.out.println("Phase " + currentPhase
+ " Complete");
System.out.println("Phase One Ended");
currentPhase = phaser.getPhase();
phaser.arriveAndAwaitAdvance();
System.out.println("Phase " + currentPhase
+ " Complete");
System.out.println("Phase Two Ended");
// Deregister the main thread.
phaser.arriveAndDeregister();
if (phaser.isTerminated()) {
System.out.println("Phaser is terminated");
}
}
}
Output
Starting
Thread: C Phase Zero Started
Thread: A Phase Zero Started
Thread: B Phase Zero Started
Thread: B Phase One Started
Thread: C Phase One Started
Thread: A Phase One Started
Phase 0 Complete
Phase Zero Ended
Phase 1 Complete
Phase One Ended
Thread: A Phase Two Started
Thread: C Phase Two Started
Thread: B Phase Two Started
Phase 2 Complete
Phase Two Ended
Phaser is terminated
方法:
- int register()–该方法用于在相位器构建完成后注册各方。它返回它注册到的阶段的阶段号。
public int register()
throws IllegalArgumentException
- int react()–这个方法表示一个线程已经完成了部分任务。它不会暂停调用线程的执行。如果相位器已经终止，它返回当前相位号或负值。
public int arrive()
throws IllegalStateException
- int arriveandunregulator()–该方法使一个线程能够到达某个阶段并注销自己，而无需等待其他线程到达。如果相位器已经终止，它返回当前相位号或负值。
public int arriveAndDeregister()
throws IllegalStateException
- int arriveandwaitadvance()–这个方法在某个阶段暂停线程的执行，等待其他线程。如果相位器已经终止，它返回当前相位号或负值。
public int arriveAndAwaitAdvance()
throws IllegalStateException
- final int getPhase()–该方法返回当前相数。如果调用阶段终止，则返回负值。
public final int getPhase()
- 布尔 onAdvance(int phase，int parties)–该方法有助于定义阶段推进应该如何发生。为此，用户必须重写此方法。要终止相位器，onAdvance()方法返回 true，否则返回 false
protected boolean onAdvance(int phase, int parties)
演示相位器类方法的示例–该方法被覆盖，因此相位器只执行指定数量的相位。
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// the methods of Phaser class
import java.util.concurrent.Phaser;
// Extend MyPhaser and override onAdvance()
// so that only specific number of phases
// are executed
class MyPhaser extends Phaser {
int numPhases;
MyPhaser(int parties, int phaseCount)
{
super(parties);
numPhases = phaseCount - 1;
}
@Override
protected boolean onAdvance(int phase,
int registeredParties)
{
System.out.println("Phase " + phase
+ " completed.\n");
// If all phases have completed, return true.
if (phase == numPhases || registeredParties == 0) {
return true;
}
// otherwise, return false
return false;
}
}
// A thread of execution that uses a phaser
class ModifiedThread implements Runnable {
Phaser phsr;
String name;
ModifiedThread(Phaser p, String n)
{
phsr = p;
name = n;
phsr.register();
new Thread(this).start();
}
@Override public void run()
{
while (!phsr.isTerminated()) {
System.out.println("Thread " + name
+ " Beginning Phase "
+ phsr.getPhase());
phsr.arriveAndAwaitAdvance();
try {
Thread.sleep(10);
}
catch (InterruptedException e) {
System.out.println(e);
}
}
}
}
public class PhaserExample2 {
public static void main(String[] args)
{
MyPhaser phsr = new MyPhaser(1, 4);
System.out.println("Starting");
new ModifiedThread(phsr, "A");
new ModifiedThread(phsr, "B");
new ModifiedThread(phsr, "C");
while (!phsr.isTerminated()) {
phsr.arriveAndAwaitAdvance();
}
System.out.println("The phaser is terminated\n");
}
}
Output
Starting
Thread B Beginning Phase 0
Thread C Beginning Phase 0
Thread A Beginning Phase 0
Phase 0 completed.
Thread A Beginning Phase 1
Thread B Beginning Phase 1
Thread C Beginning Phase 1
Phase 1 completed.
Thread C Beginning Phase 2
Thread A Beginning Phase 2
Thread B Beginning Phase 2
Phase 2 completed.
Thread A Beginning Phase 3
Thread B Beginning Phase 3
Thread C Beginning Phase 3
Phase 3 completed.
The phaser is terminated
参考:https://docs . Oracle . com/javase/9/docs/API/Java/util/concurrent/phaser . html
版权属于：月萌API www.moonapi.com，转载请注明出处
