本文主要是介绍java 线程池中 execute 和 submit 方法的区别，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
ThreadPoolExecutor UML类图
execute 方法定义
public interface Executor {void execute(Runnable command);
}
submit 方法定义
public interface ExecutorService extends Executor {<T> Future<T> submit(Callable<T> task);<T> Future<T> submit(Runnable task, T result);Future<?> submit(Runnable task);
}
submit 方法具体实现
public abstract class AbstractExecutorService implements ExecutorService {public Future<?> submit(Runnable task) {if (task == null) throw new NullPointerException();RunnableFuture<Void> ftask = newTaskFor(task, null);execute(ftask);return ftask;}public <T> Future<T> submit(Runnable task, T result) {if (task == null) throw new NullPointerException();RunnableFuture<T> ftask = newTaskFor(task, result);execute(ftask);return ftask;}public <T> Future<T> submit(Callable<T> task) {if (task == null) throw new NullPointerException();RunnableFuture<T> ftask = newTaskFor(task);execute(ftask);return ftask;}
}
execute 方法具体实现
public class ThreadPoolExecutor extends AbstractExecutorService {public void execute(Runnable command) {// 具体实现}
}
程序验证
public class ExecuteVsSubmit {public static final SimpleDateFormat SDF = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");// 线程池核心线程最大线程数private static final int MAX_THREAD_SIZE = 10;public static void main(String[] args) throws Exception {// 模拟请求列表List<String> requests = Lists.newArrayList("A0001", "A0002", "A0003", "A0004", "A0005", "B0001", "B0002", "B0003", "B0004", "B0005");ExecutorService executor = Executors.newFixedThreadPool(requests.size() > MAX_THREAD_SIZE ? MAX_THREAD_SIZE : requests.size());// 只在 submit 方式-2 和 submit 方式-3 中用到List<Future<Response>> futures = new ArrayList<>();System.out.println(SDF.format(new Date()) + " 发送请求~~~");for (String request : requests) {// execute 方式 (第二个参数意义不大, 可以参考 `submit 方式-2-2` 的调用方式)
// executor.execute(new TaskRunnable(request, new Response()));// submit 方式-1 (第二个参数意义不大, 可以参考 `submit 方式-2-2` 的调用方式)
// executor.submit(new TaskRunnable(request, new Response()));// submit 方式-2-1
// Response response = new Response();
// Future<Response> future = executor.submit(new TaskRunnable(request, response), response);
// futures.add(future);// submit 方式-2-2Response response = new Response();Future<Response> future = executor.submit(() -> {System.out.println(String.format("%s 异步请求接口=[%s]",ExecuteVsSubmit.SDF.format(new Date()), request));try {Thread.sleep(5 * 1000);response.setMsg(request);} catch (InterruptedException e) {e.printStackTrace();}}, response);futures.add(future);// submit 方式-3
// Future<Response> future = executor.submit(new TaskCallable(request));
// futures.add(future);}// 获取异步结果for (Future<Response> future : futures) {System.out.println(SDF.format(new Date()) + " 结果=" + future.get().getMsg());}executor.shutdown();}}class TaskCallable implements Callable<Response> {private String request;public TaskCallable(String request) {this.request = request;}@Overridepublic Response call() throws Exception {System.out.println(String.format("%s 异步请求接口=[%s]",ExecuteVsSubmit.SDF.format(new Date()), this.request));try {Thread.sleep(5 * 1000);} catch (InterruptedException e) {e.printStackTrace();}return new Response(request);}
}class TaskRunnable implements Runnable {private String request;private Response response;public TaskRunnable(String request, Response response) {this.request = request;this.response = response;}@Overridepublic void run() {System.out.println(String.format("%s 异步请求接口=[%s]",ExecuteVsSubmit.SDF.format(new Date()), this.request));try {Thread.sleep(5 * 1000);response.setMsg(request);} catch (InterruptedException e) {e.printStackTrace();}}
}@Data
@NoArgsConstructor
@AllArgsConstructor
class Response {private String msg;
}
- execute和submit都属于线程池的方法，execute只能提交Runnable类型的任务，而submit既能提交Runnable类型任务也能提交Callable类型任务。
- execute会直接抛出任务执行时的异常，submit会吃掉异常，可通过Future的get方法将任务执行时的异常重新抛出。
- execute所属顶层接口是Executor,submit所属顶层接口是ExecutorService，实现类ThreadPoolExecutor重写了execute方法,抽象类AbstractExecutorService重写了submit方法。
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