/**
 * jdk1.8之前的Future
 * 
 * @author Administrator
 *
 */
public class JavaFuture {
	public static void main(String[] args) throws Throwable, ExecutionException {
		ExecutorService executor = Executors.newFixedThreadPool(1);
		// Future代表了線程執(zhí)行完以后的結(jié)果，可以通過future獲得執(zhí)行的結(jié)果
		// 但是jdk1.8之前的Future有點雞肋，并不能實現(xiàn)真正的異步，需要阻塞的獲取結(jié)果，或者不斷的輪詢
		// 通常我們希望當(dāng)線程執(zhí)行完一些耗時的任務(wù)后，能夠自動的通知我們結(jié)果，很遺憾這在原生jdk1.8之前
		// 是不支持的，但是我們可以通過第三方的庫實現(xiàn)真正的異步回調(diào)
		Future<String> f = executor.submit(new Callable<String>() {
 
			@Override
			public String call() throws Exception {
				System.out.println("task started!");
				Thread.sleep(3000);
				System.out.println("task finished!");
				return "hello";
			}
		});
 
		//此處阻塞main線程
		System.out.println(f.get());
		System.out.println("main thread is blocked");
	}
}

package guava;
 
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
 
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
 
/**
 * Guava中的Future
 * 
 * @author Administrator
 *
 */
public class GuavaFuture {
	public static void main(String[] args) {
		ExecutorService executor = Executors.newFixedThreadPool(1);
 
		// 使用guava提供的MoreExecutors工具類包裝原始的線程池
		ListeningExecutorService listeningExecutor = MoreExecutors.listeningDecorator(executor);
		//向線程池中提交一個任務(wù)后，將會返回一個可監(jiān)聽的Future，該Future由Guava框架提供
		ListenableFuture<String> lf = listeningExecutor.submit(new Callable<String>() {
 
			@Override
			public String call() throws Exception {
				System.out.println("task started!");
				//模擬耗時操作
				Thread.sleep(3000);
				System.out.println("task finished!");
				return "hello";
			}
		});
		//添加回調(diào)，回調(diào)由executor中的線程觸發(fā)，但也可以指定一個新的線程
		Futures.addCallback(lf, new FutureCallback<String>() {
 
			//耗時任務(wù)執(zhí)行失敗后回調(diào)該方法
			@Override
			public void onFailure(Throwable t) {
				System.out.println("failure");
			}
			
			//耗時任務(wù)執(zhí)行成功后回調(diào)該方法
			@Override
			public void onSuccess(String s) {
				System.out.println("success " + s);
			}
		});
		
		//主線程可以繼續(xù)做其他的工作
		System.out.println("main thread is running");
	}
}

package netty_promise;
 
import io.netty.util.concurrent.DefaultEventExecutorGroup;
import io.netty.util.concurrent.EventExecutorGroup;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.FutureListener;
 
/**
 * netty中的promise
 * 
 * @author Administrator
 *
 */
public class PromiseTest {
	@SuppressWarnings({ "unchecked", "rawtypes" })
	public static void main(String[] args) throws Throwable {
		//線程池
		EventExecutorGroup group = new DefaultEventExecutorGroup(1);
		//向線程池中提交任務(wù)，并返回Future，該Future是netty自己實現(xiàn)的future
		//位于io.netty.util.concurrent包下，此處運(yùn)行時的類型為PromiseTask
		Future<?> f = group.submit(new Runnable() {
			
			@Override
			public void run() {
				System.out.println("任務(wù)正在執(zhí)行");
				//模擬耗時操作，比如IO操作
				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				System.out.println("任務(wù)執(zhí)行完畢");
			}
		});
		//增加監(jiān)聽
		f.addListener( new FutureListener() {
			@Override
			public void operationComplete(Future arg0) throws Exception {
				System.out.println("ok!!!");
			}
		});
		System.out.println("main thread is running.");
	}
}

package netty_promise;
 
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.function.Supplier;
 
/**
 * 基于jdk1.8實現(xiàn)任務(wù)異步處理
 * 
 * @author Administrator
 *
 */
public class JavaPromise {
	public static void main(String[] args) throws Throwable, ExecutionException {
		// 兩個線程的線程池
		ExecutorService executor = Executors.newFixedThreadPool(2);
		//jdk1.8之前的實現(xiàn)方式
		CompletableFuture<String> future = CompletableFuture.supplyAsync(new Supplier<String>() {
			@Override
			public String get() {
				System.out.println("task started!");
				try {
					//模擬耗時操作
					Thread.sleep(2000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				return "task finished!";
			}
		}, executor);
 
		//采用lambada的實現(xiàn)方式
		future.thenAccept(e -> System.out.println(e + " ok"));
		
		System.out.println("main thread is running");
	}
}