公平锁与非公平锁

src/main/java/thread_demo/demo43/MyService.java

@@ -0,0 +1,26 @@
+package thread_demo.demo43;
+
+import java.util.concurrent.locks.ReentrantLock;
+
+public class MyService {
+
+    private ReentrantLock lock;
+
+    public MyService(boolean isFair) {
+        this.lock = new ReentrantLock(isFair);
+    }
+
+    public void method1() {
+        System.out.println("thread name : " + Thread.currentThread().getName() + " 尝试获取锁, at " + System.currentTimeMillis());
+        lock.lock();
+        System.out.println("thread name : " + Thread.currentThread().getName() + " 获取到了锁");
+        lock.unlock();
+    }
+
+    public void method2() throws InterruptedException {
+        lock.lock();
+        Thread.sleep(5000);
+        System.out.println("method2 释放锁");
+        lock.unlock();
+    }
+}

src/main/java/thread_demo/demo43/MyThread.java

@@ -0,0 +1,15 @@
+package thread_demo.demo43;
+
+public class MyThread extends Thread {
+
+    private MyService service;
+
+    public MyThread(MyService service) {
+        this.service = service;
+    }
+
+    @Override
+    public void run() {
+        service.method1();
+    }
+}

src/main/java/thread_demo/demo43/Run.java

@@ -0,0 +1,43 @@
+package thread_demo.demo43;
+
+/**
+ *公平锁与非公平锁 :
+ *      公平锁 : 线程获取锁的顺序是按照线程加载锁的顺序来的(FIFO的顺序)
+ *      非公平锁 : 线程获取锁的顺序是随机的，和线程加载锁的顺序没有关系
+ *
+ * new ReentrantLock(true) : 公平锁； new ReentrantLock(false) : 非公平锁
+ */
+public class Run {
+
+    public static void main(String[] args) throws InterruptedException {
+
+        final MyService service = new MyService(true);
+        //TODO
+        //好像都是公平锁，为什么没有效果？
+//        final MyService service = new MyService(false);
+
+        Thread[] threads = new Thread[40];
+        for (int i = 0; i < threads.length; i++) {
+            threads[i] = new MyThread(service);
+        }
+
+        new Thread() {
+            @Override
+            public void run() {
+                try {
+                    service.method2();
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            }
+        }.start();
+
+        Thread.sleep(100);
+
+        for (int i = 0; i < threads.length; i++) {
+            threads[i].start();
+            Thread.sleep(100);
+        }
+    }
+
+}

src/main/java/thread_demo/description.md

@@ -51,4 +51,6 @@ demo40 : InheritableThreadLocal使用。
 
 demo41 : ReentrantLock使用。
 
-demo42 : Condition调用await、signal方法进行等待、唤醒。
+demo42 : Condition调用await、signal方法进行等待、唤醒。
+
+demo43 : new ReentrantLock(true) : 公平锁；new ReentrantLock(false) : 非公平锁。