Java注解（二）

Demo目录结构：

image.png

代码：

package annotationdemotwo;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @author Sandy
 * @version ClassInfo.java, v 0.1 2018-04-26 下午6:25
 */

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface ClassInfo {
    String value();
}

package annotationdemotwo;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @author Sandy
 * @version MethodInfo.java, v 0.1 2018-04-26
 */

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface MethodInfo {
    String name() default "long";
    String data();
    int age() default 27;
}

package annotationdemotwo;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @author Sandy
 * @version FieldInfo.java, v 0.1 2018-04-26
 */

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface FieldInfo {
    int[] value();
}

package annotationdemotwo;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;

/**
 * @author Sandy
 * @version TestRuntimeAnnotation.java, v 0.1 2018-04-26
 */

@ClassInfo("Test Class")
public class TestRuntimeAnnotation {

    @FieldInfo(value = {1,2})
    public  String filedInfo = "FieldInfo";

    @FieldInfo(value = {10086})
    public int i = 100;

    @MethodInfo(name = "Monica", data = "Big")
    public static String getMethodInfo(){
        return TestRuntimeAnnotation.class.getSimpleName();
    }

    public static void main(String[] args) {

        StringBuilder stringBuilder = new StringBuilder();

        Class clazz = TestRuntimeAnnotation.class;
        Method[] methods = clazz.getDeclaredMethods();
        Field[] fields = clazz.getFields();
        Constructor[] constructor = clazz.getConstructors();

        //获取Class类型注解
        stringBuilder.append("Class注解：").append("\n");
        Annotation[] annotations = clazz.getAnnotations();
        if (annotations != null)
        {
            stringBuilder.append(Modifier.toString(clazz.getModifiers())).append(" ")
                    .append(clazz.getSimpleName()).append("\n");
            stringBuilder.append("注解值：").append(Arrays.toString(annotations)).append("\n\n");
        }

        //获取Method类型的注解
        stringBuilder.append("Method注解：").append("\n");
        for(Method method : methods){
            annotations = method.getDeclaredAnnotations();
            if (annotations != null){
                stringBuilder.append(Modifier.toString(method.getModifiers())).append(" ")
                        .append(method.getReturnType().getSimpleName()).append(" ")
                        .append(method.getName()).append("\n");
                stringBuilder.append("注解值：").append(Arrays.toString(annotations)).append("\n\n");
            }
        }

        //获取Field类型的注解
        stringBuilder.append("Field注解：").append("\n");
        for(Field field : fields){
            annotations = field.getDeclaredAnnotations();
            if (annotations != null){
                stringBuilder.append(Modifier.toString(field.getModifiers())).append(" ")
                        .append(field.getType().getSimpleName()).append(" ")
                        .append(field.getName()).append("\n");
                stringBuilder.append("注解值：").append(Arrays.toString(annotations)).append("\n\n");
            }
        }

        System.out.println(stringBuilder.toString());
    }
}

输出：

image.png