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Add Stage3 Lesson 4
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15 files changed

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‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-2/lesson-4/src/main/java/com/segmentfault/deep/in/java/collection/algorithm/QuickSort.java

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package com.segmentfault.deep.in.java.collection.algorithm;
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import java.util.Arrays;
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import java.util.stream.Stream;
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public class QuickSort<T extends Comparable<T>> implements Sort<T> {
@@ -82,9 +83,9 @@ int partition(T[] values, int low, int high) {
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}
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public static void main(String[] args) {
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Integer[] values = Sort.of(3, 1, 2, 5, 4);
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Integer[] values = Sort.of(2, 5, 6, 7, 8, 8, 9, 2, 1, 6, 7, 5, 6, 11, 23);
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Sort<Integer> sort = new QuickSort<>(); // Java 7 Diamond 语法
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sort.sort(values);
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Stream.of(values).forEach(System.out::println);
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System.out.println(Arrays.asList(values));
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/pom.xml

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<module>stage-3-lesson-1</module>
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<module>stage-3-lesson-2</module>
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<module>stage-3-lesson-3</module>
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<module>stage-3-lesson-4</module>
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</modules>
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<packaging>pom</packaging>
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‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/pom.xml

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<parent>
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<artifactId>stage-3</artifactId>
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<groupId>com.segmentfault</groupId>
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<version>1.0-SNAPSHOT</version>
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</parent>
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<modelVersion>4.0.0</modelVersion>
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<artifactId>stage-3-lesson-4</artifactId>
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<name>「一入 Java 深似海 」系列 :: 第三期 :: 第四节</name>
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<url>https://segmentfault.com/ls/1650000018320970/l/1500000018320681</url>
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</project>

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueConcurrentDemo.java

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package com.segmentfault.deep.in.java.concurrency;
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import java.util.concurrent.*;
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import java.util.concurrent.atomic.AtomicInteger;
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public class ArrayBlockingQueueConcurrentDemo {
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public static void main(String[] args) throws InterruptedException {
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// 最大允许添加 2 个元素
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BlockingQueue<Integer> queue = new ArrayBlockingQueue<>(2, true);
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// 申请 2 个大小的线程池
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ExecutorService executorService = Executors.newFixedThreadPool(2);
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for (AtomicInteger i = new AtomicInteger(1); i.get() < 100; i.incrementAndGet()) {
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executorService.submit(() -> { // 写线程（1）
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try {
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queue.put(i.get());
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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});
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executorService.submit(() -> { // 读线程（1）
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try {
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System.out.println(queue.take());
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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});
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}
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// executorService.submit(() -> { // 写线程（2）
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// queue.put(2);
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// });
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executorService.awaitTermination(10, TimeUnit.SECONDS);
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// 关闭线程池
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executorService.shutdown();
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ArrayBlockingQueueDemo.java

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package com.segmentfault.deep.in.java.concurrency;
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import java.util.concurrent.ArrayBlockingQueue;
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import java.util.concurrent.BlockingQueue;
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public class ArrayBlockingQueueDemo {
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public static void main(String[] args) throws InterruptedException {
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// ArrayBlockingQueue 是有限队列
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ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue(3);
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// Queue 添加操作中 offer 安全性高于 add 方法
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// demoOfferMethod(queue);
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// demoAddMethod(queue);
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demoPutMethod(queue);
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// BlockingQueue 要使用 put 方法多于 offer 方法
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System.out.println(queue);
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}
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private static void demoPutMethod(BlockingQueue<Integer> queue) throws InterruptedException {
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queue.put(1);
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queue.put(2);
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queue.put(3);
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// 如果超过了 capacity，？
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queue.put(4);
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}
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private static void demoAddMethod(BlockingQueue<Integer> queue) {
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queue.add(1);
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queue.add(2);
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queue.add(3);
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// 如果超过了 capacity，throw new IllegalStateException("Queue full")
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// queue.add(4);
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}
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private static void demoOfferMethod(BlockingQueue<Integer> queue) {
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queue.offer(1);
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queue.offer(2);
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queue.offer(3);
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// 如果超过了 capacity，后面的offer 会被忽略
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queue.offer(4);
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CompletableFutureDemo.java

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package com.segmentfault.deep.in.java.concurrency;
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import java.util.concurrent.CompletableFuture;
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public class CompletableFutureDemo {
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public static void main(String[] args) {
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// CompletableFuture
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CompletableFuture.supplyAsync(() -> {
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return 1;
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}).thenApply(String::valueOf)
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// 异常的方式结束
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.completeExceptionally(new RuntimeException())
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;
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/ConcurrentHashMapDemo.java

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package com.segmentfault.deep.in.java.concurrency;
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public class ConcurrentHashMapDemo {
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public static void main(String[] args) {
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// ConcurrentHashMap 读多写少场景
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// 1.6 读（部分锁） -> 1.7 无锁（Segment） -> 1.8 无锁（红黑树——更好地解决 Hash 冲突）
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// ConcurrentSkipListMap 读多写多场景（如果内存足够时）
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// ConcurrentHashMap
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// table 2^n ->
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// n = 1 -> size = 2
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// n = 2 -> size = 2^2 = 4
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// n = 3 -> size = 2^3 = 8 TREEIFY_THRESHOLD
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// log2(8) = 3
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// [0] -> [1] -> [2]
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// [0] -> [1]
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// -> [2]
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// n = 4 -> size = 2^4 = 16
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/CopyOnWriteArrayListDemo.java

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package com.segmentfault.deep.in.java.concurrency;
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import java.util.Iterator;
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import java.util.concurrent.CopyOnWriteArrayList;
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public class CopyOnWriteArrayListDemo {
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public static void main(String[] args) {
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CopyOnWriteArrayList<Integer> list = new CopyOnWriteArrayList<>(); // Diamond 语法
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// main 线程插入三条数据
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// 安装 Thread ID
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list.add(1);
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// 判断当前线程 ID == main.threadId
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list.add(2);
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list.add(3);
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// Copy
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// JDK 升级两大核心性能提升
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// 1. 数组
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// 2. String
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// ConcurrentModificationException
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int times = 0;
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Iterator iterator = list.iterator();
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while (iterator.hasNext() && times < 100) {
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iterator.next();
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list.add(2);
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times++;
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}
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/HashMapDemo.java

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package com.segmentfault.deep.in.java.concurrency;
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import java.util.HashMap;
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import java.util.Map;
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public class HashMapDemo {
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public static void main(String[] args) {
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String strValue = "Hello,World";
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Integer intValue = new Integer(strValue.hashCode());
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Map<Object, Object> map = new HashMap<>();
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map.put(strValue, 1);
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map.put(intValue, 2);
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}
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}

‎「一入 Java 深似海 」/代码/segmentfault/deep-in-java/stage-3/stage-3-lesson-4/src/main/java/com/segmentfault/deep/in/java/concurrency/Java9FlowDemo.java

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package com.segmentfault.deep.in.java.concurrency;
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import java.util.concurrent.*;
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public class Java9FlowDemo {
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public static void main(String[] args) throws InterruptedException {
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// Java 7 try-catch 语法
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try (SubmissionPublisher<String> publisher = new SubmissionPublisher<>()) {
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// 订阅
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publisher.subscribe(new Flow.Subscriber<String>() {
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private Flow.Subscription subscription;
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@Override
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public void onSubscribe(Flow.Subscription subscription) {
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this.subscription = subscription;
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println("已订阅");
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// 订阅无限(Long.MAX_VALUE)数据
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subscription.request(Long.MAX_VALUE);
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}
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@Override
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public void onNext(String item) {
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if ("exit".equalsIgnoreCase(item)) {
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// 取消订阅
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subscription.cancel();
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return;
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} else if ("exception".equalsIgnoreCase(item)) {
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throw new RuntimeException("Throw an exception...");
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}
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println("得到数据：" + item);
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}
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@Override
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public void onError(Throwable throwable) {
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println("得到异常：" + throwable);
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}
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@Override
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public void onComplete() {
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println("操作完成");
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}
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});
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// 发布者发布数据
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publisher.submit("Hello,World");
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publisher.submit("2019");
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// 故意抛出异常
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publisher.submit("exception");
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// exit 是退出命令
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publisher.submit("exit");
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// 当 exit 出现时，忽略后续提交
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publisher.submit("ABCDEFG");
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publisher.submit("HIGKLMN");
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ExecutorService executor = (ExecutorService) publisher.getExecutor();
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executor.awaitTermination(100, TimeUnit.MILLISECONDS);
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}
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}
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private static void println(Object object) {
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System.out.printf("[线程: %s] - %s\n", Thread.currentThread().getName(), object);
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}
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}

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