Java中的类 getAnnotations() 方法和示例
Java.lang.Class 类的getAnnotations()方法用于获取此类中存在的注解。该方法返回一个存在的注释数组。
句法:
public Annotation[] getAnnotations()
参数:此方法不接受任何参数。
返回值:此方法返回存在的注释数组。
下面的程序演示了 getAnnotations() 方法。
示例 1:
// Java program to demonstrate
// getAnnotations() method
import java.util.*;
import java.lang.annotation.*;
@Deprecated
public class Test {
public Object obj;
public static void main(String[] args)
throws ClassNotFoundException
{
try {
// returns the Class object for this class
Class myClass = Test.class;
System.out.println(
"Class represented by myClass: "
+ myClass.toString());
// Get the annotation
// using getAnnotations() method
System.out.println(
"Annotation of myClass: "
+ Arrays.toString(
myClass.getAnnotations()));
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出:
Class represented by myClass: class Test
Annotation of myClass: [@java.lang.Deprecated()]
示例 2:
// Java program to demonstrate
// getAnnotations() method
import java.util.*;
import java.lang.annotation.*;
// create a custom Annotation
@Retention(RetentionPolicy.RUNTIME)
@interface Annotation {
// This annotation has two attributes.
public String key();
public String value();
}
// call Annotation for method
// and pass values for annotation
@Annotation(key = "GFG", value = "GeeksForGeeks")
public class Test {
public Object obj;
public static void main(String[] args)
throws ClassNotFoundException
{
// returns the Class object for this class
Class myClass = Test.class;
System.out.println(
"Class represented by myClass: "
+ myClass.toString());
// Get the annotation
// using getAnnotations() method
System.out.println(
"Annotation of myClass: "
+ Arrays.toString(
myClass.getAnnotations()));
}
}
输出:
Class represented by myClass: class Test
Annotation of myClass: [@Annotation(key=GFG, value=GeeksForGeeks)]
参考: https://docs.oracle.com/javase/9/docs/api/ Java/lang/Class.html#getAnnotations–