Java并行编程：从并行任务集获取反馈

import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.ArrayList;
import java.util.List;

public class Concurrency2 {
	public static void main(String[] args) {
		try {
			ThreadPoolExecutor executor = new ThreadPoolExecutor(30, 30, 1,
					TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
			List<Future<Boolean>> futures = new ArrayList<Future<Boolean>>(9000);
			// 发送垃圾邮件, 用户名假设为4位数字
			for (int i = 1000; i < 10000; i++) {
				futures.add(executor.submit(new FictionalEmailSender(i
						+ "@sina.com", "Knock, knock, Neo",
						"The Matrix has you...")));
			}
			// 提交所有的任务后,关闭executor
			System.out.println("Starting shutdown...");
			executor.shutdown();

			// 每秒钟打印执行进度
			while (!executor.isTerminated()) {
				executor.awaitTermination(1, TimeUnit.SECONDS);
				int progress = Math
						.round((executor.getCompletedTaskCount() * 100)
								/ executor.getTaskCount());
				System.out.println(progress + "% done ("
						+ executor.getCompletedTaskCount()
						+ " emails have been sent).");
			}
			// 现在所有邮件已发送完, 检查futures, 看成功发送的邮件有多少
			int errorCount = 0;
			int successCount = 0;
			for (Future<Boolean> future : futures) {
				if (future.get()) {
					successCount++;
				} else {
					errorCount++;
				}
			}
			System.out.println(successCount
					+ " emails were successfully sent, but " + errorCount
					+ " failed.");
		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}
}

class FictionalEmailSender implements Callable<Boolean> {
	private String to;
	private String subject;
	private String body;

	public FictionalEmailSender(String to, String subject, String body) {
		this.setTo(to);
		this.setSubject(subject);
		this.setBody(body);
	}

	@Override
	public Boolean call() throws InterruptedException {
		// 在0~0.5秒间模拟发送邮件
		Thread.sleep(Math.round(Math.random() * 0.5 * 1000));
		// 假设我们有80%的几率成功发送邮件
		if (Math.random() > 0.2) {
			return true;
		} else {
			return false;
		}
	}

	public String getBody() {
		return body;
	}

	public void setBody(String body) {
		this.body = body;
	}

	public String getSubject() {
		return subject;
	}

	public void setSubject(String subject) {
		this.subject = subject;
	}

	public String getTo() {
		return to;
	}

	public void setTo(String to) {
		this.to = to;
	}

}