从oracle的官方文档来学习annotations:
地址在: http://docs.oracle.com/javase/tutorial/java/javaOO/annotations.html
总结如下:
Annotations我理解就是程序的一些元数据,没有它程序也是ok的。它的主要用途体现在以下几个方面:
1. 替代以前简单的注释;
比如以前的注释可能是:
- /*
- author: Benjamin Franklin
- date: 3/27/2010
- */
/* author: Benjamin Franklin date: 3/27/2010 */
class My Class {}
用Annotations可以写成:
- @Author(
- name = "Benjamin Franklin",
- date = "3/27/2010"
- )
- class MyClass() { }
@Author( name = "Benjamin Franklin", date = "3/27/2010" ) class MyClass() { }
再复杂一点的注释:
- public class Generation3List extends Generation2List {
- // Author: John Doe
- // Date: 3/17/2002
- // Current revision: 6
- // Last modified: 4/12/2004
- // By: Jane Doe
- // Reviewers: Alice, Bill, Cindy
- // class code goes here
- }
public class Generation3List extends Generation2List { // Author: John Doe // Date: 3/17/2002 // Current revision: 6 // Last modified: 4/12/2004 // By: Jane Doe // Reviewers: Alice, Bill, Cindy // class code goes here }