JDK7新特性

JDK7新特性... 1

Modularization 模块化... 1

Multi-Language Support 多语言支持... 2

Developer Productivity 开发者生产力... 2

Performance 性能... 2

 

Java Development Kit 7 (JDK 7) is the next major release of the Java SE platform. Through the OpenJDK project, JDK 7 has been a highly collaborative effort between Sun and volunteers from the Java developer community. Sun extends its gratitude to all who have contributed to this release.

Download the JDK 7 Early Access

Key Features

JDK7是OpenJDK项目下一次JavaSE平台的主要发布，JDK7得益于Sun公司和Java开发者社区的志愿者之间的高度合作。Sun公司也给感谢每一位致力过这一发布的人。

 

JDK 7 introduces several key features to improve performance, usability, and security of the Java platform. A detailed list of these features appears on the OpenJDK site.

JDK7引入了几个主要特性来改善Java平台的执行性能，可用性和安全性。有关这些特性的详细信息在OpenJDK网站上。

 

Based on the feedback from the developer community and Sun's customers, the JDK 7 features primarily focus on the following areas.

基于社区开发者和Sun的客户的反馈，JDK7新特性主要集中在下面这几个方面。

Modularization 模块化
A large-scale effort to refactor, or break up, the Java SE platform into smaller, separate, interdependent modules. Individual modules can then be downloaded as required by the Java virtual machine and/or Java applications. This effectively shrinks the size of the runtime on the user's machine.

此次发布中，花了很大的努力把JavaSE平台重构，打散成更小的，分开，独立的若干模块。各个独立的模块能够根据JavaVM或者Java应用的需要被分别下载。这极大的减小了用户机器上Java Runtime的大小。

 

One benefit of modularization is that the platform is a smaller download, potentially improving start-up performance. Having a smaller memory footprint also enables significant performance improvements, especially for desktop applications. A smaller platform also means it can now fit on devices with less memory.

模块化的另一个好处是JavaSE平台的下载更小了，这样就无形中加快了启动速度。更小的内存需求也使得执行性能得到极大的提高，特别是对桌面应用程序。一个更小的平台也意味着它现在可以适用在内存不多的设备上。

 

You can find more information about modularization on the OpenJDK site, on Mark Reinhold's blog , or on the Project Jigsaw site.

你能在OpenJDK网站上Mark Reinhold的博客里找到更多的有关模块化的信息，或者在Project Jigsaw网站上。

Multi-Language Support 多语言支持
Improves compatibility between Java and various dynamic languages, such as Ruby and Python, by providing better-than-native implementations of these languages on top of the Java Runtime Environment (JRE).

通过在JRE上提供比本地实现更好的实现，提高Java和多个动态语言之间的兼容性，如Ruby和Python。

 

Refer to JSR 292a>, also called “InvokeDynamic”. This JSR defines the elements critical for Ruby, Python, and other dynamic languages to be addressed for JDK 7.

 

You can find more information on the Da Vinci Machine project page or on the Sun wiki site.

Developer Productivity 开发者生产力
JDK 7 will also include several features to enhance developer productivity. One of Sun's goals is to make JDK 7, and other versions of the JDK, as developer-friendly as possible. Here are some features in JDK 7 to do just that:

Project Coin: Small language changes

Concurrency and Collections Updates

JSR 308: Type Annotations to improve static program checking

JSR 203: New I/O to define a true filesystem API

JDK7也包括一些提高开发者生产力的新特这。Sun开发JDK7和其他后继版本的目标之一是做到尽可能的对开发者友好。一下是这些新特性用以实现这个目标：

项目代价：小的语言改变

并发和Java Collection机制得到更新

JSR 308：类型注释加强静态程序检查

JSR 203：新IO定义真正的文件系统API

Performance 性能
Sun understands the need to improve the performance of the Java SE platform, and several features in JDK 7 address just that. Here are two such features slated for JDK 7:

Compressed 64-bit object pointers

G1 Garbage Collector

The new Garbage First (G1) Garbage Collector is a low pause, server-style garbage collector that will eventually replace the Concurrent Mark-Sweep (CMS) garbage collector. G1's primary advantage over CMS are incremental compaction, better predictability, and ease of use. You can find more information on the OpenJDK site or on Alex Miller's blog.

Sun理解改善JavaSE平台性能的需要，好几个JDK7的新特性搞好说明了这一点。这里是铺设在JDK7里的两个那样的新特性。

压缩的64位的对象指针

G1（Garbage First）垃圾回收器

新的G1是低暂停，服务器模式的垃圾回收器，它将最终代替CMS（Concurrent Mark-Sweep）垃圾回收器。相比CMS，G1的好处是高压缩，更好的可预言性和易用性。