package testannotation;import java.lang.annotation.Documented;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;import java.lang.reflect.Field;import java.lang.reflect.Method;/** * @Target说明了Annotation所修饰的对象范围 * @Retention定义了该Annotation被保留的时间长短 * @Documented用于描述其它类型的annotation应该被作为被标注的程序成员的公共API */@Documented@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.TYPE)@interface TypeAnnotation {    String value() default "DefaultTypeAnnotation";}@Documented@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.METHOD)@interface MethodAnnotation {    String name() default "Default Annotation Name";    String url() default "default.com";}@Documented@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.FIELD)@interface FieldAnnotation {    String value() default "DefaultFieldAnnotation";}@TypeAnnotation("Test the use of TypeAnnotation")class UseAnnotion {    @FieldAnnotation(value="FieldAnnotation with value")    private String field;        @FieldAnnotation    private String fieldWithDefault;        @MethodAnnotation()    public void testMethodAnnotation() {        System.out.println("UseAnnotion->testMethodAnnotation");    }        @MethodAnnotation(name="唯品会",url="vip.com")    public void testMethodAnnotationWithValue() {        System.out.println("UseAnnotion->testMethodAnnotationWithValue");    }}public class TestAnnotation {    public static void main(String[] args) throws ClassNotFoundException {        Class anno = Class.forName("testannotation.UseAnnotion");        Method[] method = anno.getMethods();        boolean flag = anno.isAnnotationPresent(TypeAnnotation.class);        if (flag) {            TypeAnnotation first = (TypeAnnotation) anno.getAnnotation(TypeAnnotation.class);            System.out.println("类型注解值:" + first.value());        }        for (Method m : method) {            MethodAnnotation methodAnno = m                    .getAnnotation(MethodAnnotation.class);            if (methodAnno == null)                continue;            System.out.println("获取方法注解\nname:\t"                    + methodAnno.name() + "\nurl:\t" + methodAnno.url());        }        Field []field = anno.getDeclaredFields();        for(Field f : field) {            FieldAnnotation fieldAnnotation = (FieldAnnotation)f.getAnnotation(FieldAnnotation.class);            System.out.println("获取域注解:"+fieldAnnotation.value());        }    }}