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// 注解的格式

The Format of an Annotation

In its simplest form, an annotation looks like the following:

@Entity

// @这个标识符告诉编辑器这是一个注解，下面以重写（Override）这个注解为例

The at sign character (@) indicates to the compiler that what follows is an annotation. In the following example, the annotation's name is Override:

@Overridevoid mySuperMethod() { ... }

// 注解可以包括属性（elements），这些属性可以是已命名的也可以的未命名的，而且他们可以有自己的属性值（values）

The annotation can include elements, which can be named or unnamed, and there are values for those elements:

@Author(   name = "Benjamin Franklin",   date = "3/27/2003")class MyClass() { ... }

or

@SuppressWarnings(value = "unchecked")void myMethod() { ... }

// 如果注解只有一个属性，而且属性名为value，那么属性名可以省略，正像下面这个例子展示的那样

If there is just one element named value, then the name can be omitted, as in:

@SuppressWarnings("unchecked")void myMethod() { ... }

//  如果注解没有属性，那么括号也可以省略，比如前面@Override的例子

If the annotation has no elements, then the parentheses can be omitted, as shown in the previous @Override example.

// 同一个位置可以使用多个注解

It is also possible to use multiple annotations on the same declaration:

@Author(name = "Jane Doe")@EBookclass MyClass { ... }

// 如果是多个同类注解，这种情况被称作多重注解

If the annotations have the same type, then this is called a repeating annotation:

@Author(name = "Jane Doe")@Author(name = "John Smith")class MyClass { ... }

// Java SE 8 release 开始支持多重注解，想了解更多，请点击链接

Repeating annotations are supported as of the Java SE 8 release. For more information, see .

// 注解可以是Java SE API里面java.lang或者java.lang.annotation这些包里面已经定义的类型，比如前面提到的Override和SuppressWarnings都是

// java预定义注解。也可以是自定义类型，前面例子展示的Author和Ebook都是这一类。

The annotation type can be one of the types that are defined in the java.lang or java.lang.annotation packages of the Java SE API. In the previous examples,Override and SuppressWarnings are . It is also possible to define your own annotation type. The Author and Ebook annotations in the previous example are custom annotation types.

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