// 1线程同步
QFutureSynchronizer<void> synchronizer;
//2线程1
synchronizer.addFuture(QtConcurrent::run([=]() {
download(url);
}));
//3线程2
synchronizer.addFuture(QtConcurrent::run([=]() {
download(webpicurl);
}));
//4等待下载完成
synchronizer.waitForFinished();
//5ToSomeThing
二、qfuture和qfuturewatch