上一篇我们共同认识了并发问题,那么本篇我们将一起来学习Callable接口实现多线程。
上篇内容我们通过实现Runnable实现多线程,本篇我们将学习如何继承java中的Callable来实现多线程。
操作步骤:
代码如下(示例):
TestCallable类
public class TestCallable implements Callable<Boolean> {
private String url;
private String name;
public TestCallable(String url, String name) {
this.url = url;
this.name = name;
}
@Override
public Boolean call() {
WebDownLoader03 webDownLoader = new WebDownLoader03();
webDownLoader.downloader(url,name);
System.out.println("下载的文件名:"+name);
return true;
}
public static void main(String[] args) throws ExecutionException, InterruptedException {
TestCallable t1 = new TestCallable("https://up.tt98.com/uploadfile/sjbz/2020-11-11/c57c4f2e092bf23ec0c8e940664d6572.jpg","1.jpg");
TestCallable t2 = new TestCallable("https://up.tt98.com/uploadfile/sjbz/2020-11-11/c57c4f2e092bf23ec0c8e940664d6572.jpg","2.jpg");
TestCallable t3 = new TestCallable("https://up.tt98.com/uploadfile/sjbz/2020-11-11/c57c4f2e092bf23ec0c8e940664d6572.jpg","3.jpg");
//创建执行服务
ExecutorService ser = Executors.newFixedThreadPool(3);
//提交执行
Future<Boolean> r1 = ser.submit(t1);
Future<Boolean> r2 = ser.submit(t2);
Future<Boolean> r3 = ser.submit(t3);
//获取结果
boolean rs1 = r1.get();
boolean rs2 = r2.get();
boolean rs3 = r3.get();
//关闭服务
ser.shutdownNow();
}
}
WebDownLoader03类
//下载器
class WebDownLoader03{
//下载方法
public void downloader(String url,String name){
try {
FileUtils.copyURLToFile(new URL(url),new File(name));
}catch (IOException e){
e.printStackTrace();
System.out.println("IO异常,downloader方法出现异常。");
}
}
}
运行结果: