Add ch17 code

Author: timerring

code/chapter17/.idea/.gitignore

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+<?xml version="1.0" encoding="UTF-8"?>
+<Diagram>
+  <ID>JAVA</ID>
+  <OriginalElement>java.lang.Thread</OriginalElement>
+  <nodes>
+    <node x="0.0" y="0.0">java.lang.FunctionalInterface</node>
+    <node x="88.5" y="190.0">java.lang.Thread</node>
+    <node x="75.0" y="95.0">java.lang.Runnable</node>
+  </nodes>
+  <notes />
+  <edges>
+    <edge source="java.lang.Runnable" target="java.lang.FunctionalInterface">
+      <point x="0.0" y="-22.5" />
+      <point x="0.0" y="22.5" />
+    </edge>
+    <edge source="java.lang.Thread" target="java.lang.Runnable">
+      <point x="0.0" y="-22.5" />
+      <point x="0.0" y="22.5" />
+    </edge>
+  </edges>
+  <settings layout="Hierarchic Group" zoom="1.0" x="160.0" y="117.5" />
+  <SelectedNodes>
+    <node>java.lang.Thread</node>
+    <node>java.lang.Runnable</node>
+  </SelectedNodes>
+  <Categories />
+  <SCOPE>All</SCOPE>
+  <VISIBILITY>private</VISIBILITY>
+</Diagram>
+

code/chapter17/.idea/misc.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

code/chapter17/.idea/modules.xml

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+package com.hspedu;
+
+
+public class CpuNum {
+    public static void main(String[] args) {
+
+        Runtime runtime = Runtime.getRuntime();
+        //获取当前电脑的cpu数量/核心数
+        int cpuNums = runtime.availableProcessors();
+        System.out.println("当前有cpu 个数=" + cpuNums);
+    }
+}

code/chapter17/.idea/uiDesigner.xml

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+package com.hspedu.exit_;
+
+public class ThreadExit_ {
+    public static void main(String[] args) throws InterruptedException {
+        T t1 = new T();
+        t1.start();
+
+        // 如果希望 main 线程去控制 t1 线程的终止, 必须可以修改 loop
+        // 让 t1 退出 run 方法，从而终止 t1 线程 -> 通知方式
+        // 让主线程休眠 10 秒，再通知 t1 线程退出
+        System.out.println("main线程休眠10s...");
+        Thread.sleep(10 * 1000);
+        t1.setLoop(false);
+    }
+}
+
+class T extends Thread {
+    private int count = 0;
+    // 设置一个控制变量
+    private boolean loop = true;
+    @Override
+    public void run() {
+        while (loop) {
+
+            try {
+                Thread.sleep(50);// 让当前线程休眠50ms
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+            System.out.println("T 运行中...." + (++count));
+        }
+    }
+    public void setLoop(boolean loop) {
+        this.loop = loop;
+    }
+}
+

code/chapter17/Thread.uml

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+package com.hspedu.homework;
+
+import java.util.Scanner;
+
+
+public class Homework01 {
+    public static void main(String[] args) {
+        A a = new A();
+        B b = new B(a);//一定要注意.
+        a.start();
+        b.start();
+    }
+}
+
+//创建A线程类
+class A extends Thread {
+    private boolean loop = true;
+
+    @Override
+    public void run() {
+        //输出1-100数字
+        while (loop) {
+            System.out.println((int)(Math.random() * 100 + 1));
+            //休眠
+            try {
+                Thread.sleep(1000);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+        System.out.println("a线程退出...");
+
+    }
+
+    public void setLoop(boolean loop) {//可以修改loop变量
+        this.loop = loop;
+    }
+}
+
+//直到第2个线程从键盘读取了“Q”命令
+class B extends Thread {
+    private A a;
+    private Scanner scanner = new Scanner(System.in);
+
+    public B(A a) {//构造器中，直接传入A类对象
+        this.a = a;
+    }
+
+    @Override
+    public void run() {
+        while (true) {
+            //接收到用户的输入
+            System.out.println("请输入你指令(Q)表示退出:");
+            char key = scanner.next().toUpperCase().charAt(0);
+            if(key == 'Q') {
+                //以通知的方式结束a线程
+                a.setLoop(false);
+                System.out.println("b线程退出.");
+                break;
+            }
+        }
+    }
+}

code/chapter17/chapter17.iml

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+package com.hspedu.homework;
+
+public class Homework02 {
+    public static void main(String[] args) {
+        T t = new T();
+        Thread thread1 = new Thread(t);
+        thread1.setName("t1");
+        Thread thread2 = new Thread(t);
+        thread2.setName("t2");
+        thread1.start();
+        thread2.start();
+    }
+}
+
+//1.因为这里涉及到多个线程共享资源，所以我们使用实现Runnable方式
+//2. 每次取出 1000
+class T implements  Runnable {
+    private int money = 10000;
+
+    @Override
+    public void run() {
+        while (true) {
+
+            //解读
+            //1. 这里使用 synchronized 实现了线程同步
+            //2. 当多个线程执行到这里时，就会去争夺 this对象锁
+            //3. 哪个线程争夺到(获取)this对象锁，就执行 synchronized 代码块, 执行完后，会释放this对象锁
+            //4. 争夺不到this对象锁，就blocked ，准备继续争夺
+            //5. this对象锁是非公平锁.
+
+            synchronized (this) {//
+                //判断余额是否够
+                if (money < 1000) {
+                    System.out.println("余额不足");
+                    break;
+                }
+
+                money -= 1000;
+                System.out.println(Thread.currentThread().getName() + " 取出了1000 当前余额=" + money);
+            }
+
+            //休眠1s
+            try {
+                Thread.sleep(1000);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}