Java多種方式實現生產者消費者模式
實現需求:兩個線程交替打印1,0,打印10輪
java多線程口訣:
高內聚,低耦合 線程操作資源類 判斷干活通知 防止虛假喚醒方式一:使用synchronized和Object的wait和notifyAll方法
wait:使當前線程阻塞
notify,notifyAll喚醒當前線程
/** * 兩個線程交替打印1,0 打印10輪 * * @author Administrator * @version 1.0 2020年7月12日 * @see ProdConsumerDemo1 * @since 1.0 * */class ShareData1 { public int number = 0; public synchronized void increment() throws Exception { while (number != 0) { this.wait(); } number++; System.out.println(Thread.currentThread().getName() + ' ' + number); this.notifyAll(); } public synchronized void decrement() throws InterruptedException { while (number != 1) { this.wait(); } number--; System.out.println(Thread.currentThread().getName() + ' ' + number); this.notifyAll(); }} public class ProdConsumerDemo1 { public static void main(String[] args) { ShareData1 shareData = new ShareData1(); new Thread(() -> { for (int i = 0; i < 10; i++) {try { shareData.increment();} catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace();} } }, 'A').start(); new Thread(() -> { for (int i = 0; i < 10; i++) {try { shareData.decrement();} catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace();} } }, 'B').start(); }}
輸出結果
A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0
方式二:使用jdk1.8的Lock和Condition
class ShareData2 { private int number = 0; private Lock lock = new ReentrantLock(); private Condition condition = lock.newCondition(); public void increment() throws Exception { lock.lock(); try { while (number != 0) {condition.await(); } number++; System.out.println(Thread.currentThread().getName() + ' ' + number); condition.signalAll(); } finally { lock.unlock(); } } public void decrement() throws InterruptedException { lock.lock(); try { while (number != 1) {condition.await(); } number--; System.out.println(Thread.currentThread().getName() + ' ' + number); condition.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } }} public class ProdConsumerDemo2 { public static void main(String[] args) { ShareData2 shareData = new ShareData2(); new Thread(() -> { for (int i = 0; i < 10; i++) {try { shareData.increment();} catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace();} } }, 'A').start(); new Thread(() -> { for (int i = 0; i < 10; i++) {try { shareData.decrement();} catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace();} } }, 'B').start(); }}
輸出結果
A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0
主要是熟悉Lock和Condition的使用
Lock和Condition相比于synchronized,能夠精確喚醒
需求:三個線程A,B,C順序打印,A打印5次,B打印10次,C打印15次,10輪
class ShareData3 { private int number = 1; private Lock lock = new ReentrantLock(); private Condition c1 = lock.newCondition(); private Condition c2 = lock.newCondition(); private Condition c3 = lock.newCondition(); public void print5() throws Exception { lock.lock(); try { while (number != 1) {c1.await(); } number = 2; for (int i = 0; i < 5; i++) {System.out.println(Thread.currentThread().getName() + ' ' + i); } c2.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } } public void print10() throws InterruptedException { lock.lock(); try { while (number != 2) {c2.await(); } number=3; for (int i = 0; i < 10; i++) {System.out.println(Thread.currentThread().getName() + ' ' + i); } c3.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } } public void print15() throws InterruptedException { lock.lock(); try { while (number != 3) {c3.await(); } number = 1; for (int i = 0; i < 15; i++) {System.out.println(Thread.currentThread().getName() + ' ' + i); } c1.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } }} public class ProdConsumerDemo3 { public static void main(String[] args) { ShareData3 shareData3 = new ShareData3(); new Thread(() -> { try {for (int i = 0; i < 10; i++) { shareData3.print5();} } catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace(); } }, 'A').start(); new Thread(() -> { try {for (int i = 0; i < 10; i++) { shareData3.print10();} } catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace(); } }, 'B').start(); new Thread(() -> { try {for (int i = 0; i < 10; i++) { shareData3.print15();} } catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace(); } }, 'C').start(); }}
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