Lesson: Concurrency课程：并发性

Computer users take it for granted that their systems can do more than one thing at a time.计算机用户理所当然地认为他们的系统一次可以做不止一件事。They assume that they can continue to work in a word processor, while other applications download files, manage the print queue, and stream audio.他们假设他们可以继续在字处理器中工作，而其他应用程序可以下载文件、管理打印队列和流式播放音频。Even a single application is often expected to do more than one thing at a time.即使是单个应用程序，通常也希望一次完成多件事情。For example, that streaming audio application must simultaneously read the digital audio off the network, decompress it, manage playback, and update its display.例如，流式音频应用程序必须同时从网络读取数字音频、解压缩、管理播放和更新其显示。Even the word processor should always be ready to respond to keyboard and mouse events, no matter how busy it is reformatting text or updating the display.即使是文字处理器也应该随时准备响应键盘和鼠标事件，无论它如何忙于重新格式化文本或更新显示。Software that can do such things is known as concurrent software.能够做这些事情的软件称为并发软件。

The Java platform is designed from the ground up to support concurrent programming, with basic concurrency support in the Java programming language and the Java class libraries.Java平台从一开始就被设计为支持并发编程，Java编程语言和Java类库提供了基本的并发支持。Since version 5.0, the Java platform has also included high-level concurrency APIs.自5.0版以来，Java平台还包括高级并发API。This lesson introduces the platform's basic concurrency support and summarizes some of the high-level APIs in the java.util.concurrent packages.本课程介绍平台的基本并发支持，并总结java.util.concurrent包中的一些高级API。