java線程池框架解析方法
Java對象實(shí)例的鎖一共有四種狀態(tài)：無鎖，偏向鎖，輕量鎖和重量鎖。原始脫離框架的并發(fā)應(yīng)用大部分都需要手動(dòng)完成加鎖釋放，最直接的就是使用synchronized和volatile關(guān)鍵字對某個(gè)對象或者代碼塊加鎖從而限制每次訪問的次數(shù)，從對象之間的競爭也可以實(shí)現(xiàn)到對象之間的'協(xié)作。但是這樣手動(dòng)實(shí)現(xiàn)出來的應(yīng)用不僅耗費(fèi)時(shí)間而且性能表現(xiàn)往往又有待提升。
一、線程池結(jié)構(gòu)圖
二、示例
定義線程接口
6public class MyThread extends Thread {@Overridepublicvoid run() {System.out.println(Thread.currentThread().getName() + "正在執(zhí)行");}}
1：newSingleThreadExecutor
10ExecutorService pool = Executors. newSingleThreadExecutor();Thread t1 = new MyThread();Thread t2 = new MyThread();Thread t3 = new MyThread();//將線程放入池中進(jìn)行執(zhí)行pool.execute(t1);pool.execute(t2);pool.execute(t3);//關(guān)閉線程池pool.shutdown();
輸入結(jié)果：
3pool-1-thread-1正在執(zhí)行pool-1-thread-1正在執(zhí)行pool-1-thread-1正在執(zhí)行
2：newFixedThreadPool
13ExecutorService pool = Executors.newFixedThreadPool(3);Thread t1 = new MyThread();Thread t2 = new MyThread();Thread t3 = new MyThread();Thread t4 = new MyThread();Thread t5 = new MyThread();//將線程放入池中進(jìn)行執(zhí)行pool.execute(t1);pool.execute(t2);pool.execute(t3);pool.execute(t4);pool.execute(t5);pool.shutdown();
輸入結(jié)果：
4pool-1-thread-1正在執(zhí)行pool-1-thread-2正在執(zhí)行pool-1-thread-1正在執(zhí)行pool-1-thread-2正在執(zhí)行
3 :newCachedThreadPool
14ExecutorService pool = Executors.newCachedThreadPool();Thread t1 = new MyThread();Thread t2 = new MyThread();Thread t3 = new MyThread();Thread t4 = new MyThread();Thread t5 = new MyThread();//將線程放入池中進(jìn)行執(zhí)行pool.execute(t1);pool.execute(t2);pool.execute(t3);pool.execute(t4);pool.execute(t5);//關(guān)閉線程池pool.shutdown();
輸入結(jié)果：
5pool-1-thread-2正在執(zhí)行pool-1-thread-4正在執(zhí)行pool-1-thread-3正在執(zhí)行pool-1-thread-1正在執(zhí)行pool-1-thread-5正在執(zhí)行
4 :ScheduledThreadPoolExecutor
14ScheduledExecutorService pool = Executors.newScheduledThreadPool(2);pool.scheduleAtFixedRate(new Runnable() {//每隔一段時(shí)間就觸發(fā)異常 @Override public void run() { //throw new RuntimeException(); System.out.println("================"); }}, 1000, 2000, TimeUnit.MILLISECONDS);pool.scheduleAtFixedRate(new Runnable() {//每隔一段時(shí)間打印系統(tǒng)時(shí)間，證明兩者是互不影響的 @Override public void run() { System.out.println("+++++++++++++++++"); }}, 1000, 2000, TimeUnit.MILLISECONDS)
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