注解的使用

[java]代码库

//显示所有注释类和方法
import java.lang.annotation.*;
import java.lang.reflect.*;
  
@Retention(RetentionPolicy.RUNTIME)
@interface MyAnno {
  String str();
  int val();
}
  
@Retention(RetentionPolicy.RUNTIME)
@interface What {
  String description();
}
  
@What(description = "An annotation test class")
@MyAnno(str = "Meta2", val = 99)
class Meta2 {
  
  @What(description = "An annotation test method")
  @MyAnno(str = "Testing", val = 100)
 
  public static void myMeth() {
    Meta2 ob = new Meta2();
  
    try {
      Annotation annos[] = ob.getClass().getAnnotations();
  
      // Display all annotations for Meta2.
      System.out.println("All annotations for Meta2:");
      for(Annotation a : annos)
        System.out.println(a);
  
      System.out.println();
  
    // Display all annotations for myMeth.
    Method m = ob.getClass( ).getMethod("myMeth");
    annos = m.getAnnotations();
  
    System.out.println("All annotations for myMeth:");
    for(Annotation a : annos)
      System.out.println(a);
    } catch (NoSuchMethodException exc) {
       System.out.println("Method Not Found.");
    }
  }
  
  public static void main(String args[]) {
    myMeth();
  }
}