Java多线程的实现方式
继承Thread ，实现Runnable， 实现Callable
callable有返回值
Thread
public class Test1_Thread {
public static void main(String[] args) {
new Test1_thread().start();
System.out.println("任务1已启动 ");
new Test1_thread().start();
System.out.println("任务2已启动 ");
}
static class Test1_thread extends Thread {
@Override
public void run() {
for (int j = 0; j < 5; j++) {
Autil.w1s(1);
Autil.printCurrent(j);
}
}
}
}Runnable
public class Test2_Runnable {
public static void main(String[] args) {
new Thread(new Test2_myRunnable()).start();
System.out.println("任务1已启动 ");
new Thread(new Test2_myRunnable()).start();
System.out.println("任务2已启动 ");
}
static class Test2_myRunnable implements Runnable {
@Override
public void run() {
for (int j = 0; j < 5; j++) {
Autil.w1s(1);
Autil.printCurrent(j);
}
}
}
}Callable
public class Test3_Callable {
/**
* 需要将任务交给线程池
*/
public static void main(String[] args) throws Exception {
// 1. 创建线程池
ExecutorService pool = Executors.newCachedThreadPool();
// 2. 向线程池提交任务
Future<Integer> future1 = pool.submit(new Test3_myCallable());
System.out.println("任务1已提交 ");
// 3. 获取线程的返回值
System.out.println("------------------开始查询所有子线程的返回值 ");
// --3.1 获取方式一： 阻塞方式等待返回值
// Integer j = future1.get();
int flag = 10;
// --3.2 获取方式二，不停的询问线程任务是否执行完成了
while (10 == flag) {
if (future1.isDone()) {
flag = 6;
System.out.println(" ");
System.out.println(flag + "返回值为 " + future1.get());
} else {
System.out.print("任务尚未完成 ");
Thread.sleep(50);
}
}
// 线程池运行结束后关闭
pool.shutdown();
System.out.println("运行结束 " + Thread.activeCount());
}
static class Test3_myCallable implements Callable<Integer> {
@Override
public Integer call() throws Exception {
Autil.w1s(1);
Autil.printCurrentTimes(3);
return 33;
}
}
}
jdk1.7: fork_join
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;
/**
* 当工作量大时，对任务进行水平拆分。
*/
public class Test9_fork {
public static void main(String[] args) throws Exception {
ForkJoinPool fjp = new ForkJoinPool();
Sum sum = new Sum(1, 1_0);
ForkJoinTask<Long> task = fjp.submit(sum);
System.out.println("提交完毕");
Long result = task.get();
System.out.println("输出结果" + result);
}
static class Sum extends RecursiveTask<Long> {
private final long from;
private final long to;
Sum(long from, long to) {
this.from = from;
this.to = to;
}
static boolean tooBiger(long from, long to) {
return (to - from) > 3 ? true : false;
}
static long sum(long from, long to) {
long sum = 0;
for (; from < to; from++) {
sum += from;
}
return sum;
}
@Override
protected Long compute() {
if (tooBiger(from, to)) {
// 任务量太大
long middle = (to + from) / 2;
Sum sum1 = new Sum(from, middle);
Sum sum2 = new Sum(middle, to);
sum1.fork();
sum2.fork();
long sum = 0;
sum = sum1.join() + sum2.join();
System.out.println(sum + " " + from + " > " + middle + " > " + to);
return sum;
} else {
long sum = sum(from, to);
System.out.println(sum + " == " + from + " > " + to);
return sum;
}
}
}
}
