线程池ExecutorService的submit和execute
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在Java5之后，并发线程这块发生了根本的变化，最重要的莫过于新的启动、调度、管理线程的一大堆API了。在Java5以后，通过 Executor来启动线程比用Thread的start()更好。在新特征中，可以很容易控制线程的启动、执行和关闭过程，还可以很容易使用线程池的特 性。
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??????? ExecutorService executorService = Executors.newCachedThreadPool();
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??????? ExecutorService executorService = Executors.newFixedThreadPool(3);
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??????? ExecutorService executorService = Executors.newSingleThreadExecutor();
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??? @Test
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??? publicvoid testDemo() throws Exception {
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?????? //单例线程，任意时间(同一时间)池中只能有一个线程
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?????? ExecutorService es = Executors.newSingleThreadExecutor();
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?????? es.execute(new Runnable() {
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?????????? @Override
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?????????? publicvoid run() {
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????????????? System.err.println("线程启动并运行"+Thread.currentThread().getName());
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?????????? }
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?????? });
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?????? es.execute(new Runnable() {
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?????????? @Override
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?????????? publicvoid run() {
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????????????? System.err.println("第二个也运行了"+Thread.currentThread().getName());
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?????????? }
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?????? });
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?????? //Thread.sleep(1000 * 60 * 60);
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线程启动并运行pool-1-thread-1
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??? @Test
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??? publicvoid testDemo3() throws Exception {
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?????? //声明一个线程池
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?????? ExecutorService ex = Executors.newCachedThreadPool();
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?????? for (int i = 0; i < 4; i++) {
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?????????? finalint a = i;
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?????????? //每一次execute方法，都是向池中放入一个对象
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?????????? ex.execute(new Runnable() {
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????????????? publicvoid run() {
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????????????????? while(true){
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???????????????????? System.err.println("测试...."+a+">"
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??????????????????????????? +Thread.currentThread().getName()+","
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??????????????????????????? +Thread.currentThread().isDaemon());
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???????????????????? try{
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???????????????????????? Thread.sleep(2000);
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???????????????????? }catch(Exception e){
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???????????????????????? e.printStackTrace();
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???????????????????? }
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????????????????? }
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????????????? }
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?????????? });
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?????? }
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?????? Thread.sleep(1000*60*60);
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测试....0>pool-1-thread-1,false
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测试....3>pool-1-thread-4,false
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测试....2>pool-1-thread-3,false
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测试....1>pool-1-thread-2,false
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测试....0>pool-1-thread-1,false
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测试....3>pool-1-thread-4,false
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测试....2>pool-1-thread-3,false
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测试....1>pool-1-thread-2,false
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测试....1>pool-1-thread-2,false
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测试....2>pool-1-thread-3,false
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测试....3>pool-1-thread-4,false
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测试....0>pool-1-thread-1,false
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??? publicvoid testCall() throws Exception{
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?????? //声明一个类，可以被调用，类似于线程，但它可以拥有返回值
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?????? class MyCall implements Callable<String>{
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?????????? privateintseq;
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?????????? public MyCall(int seq){
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????????????? this.seq=seq;
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?????????? }
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?????????? //抛出异常并可以拥有返回值
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?????????? public String call() throws Exception {
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????????????? System.err.println("执行"+seq+","+Thread.currentThread().getName());
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????????????? Thread.sleep(3000);
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????????????? System.err.println("Weak up "+seq);
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????????????? return"完成"+seq;//这是返回值
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?????????? }
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?????? }
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?????? ExecutorService es = Executors.newCachedThreadPool();//创建线程池对象
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?????? List<Future<String>> result =new ArrayList<Future<String>>();//放结果用的集合
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?????? for(int i=0;i<3;i++){
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?????????? Future<String> f=es.submit(new MyCall(i));//线程执行完成以后可以通过引用获取返回值
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?????????? result.add(f);
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?????? }
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?????? for(Future<String> f:result){
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?????????? System.err.println("返回值："+f.get());//输出返回的值
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?????? }
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?????? System.err.println("完成....");
??? }
