反射-注解-Java

package com.foreign;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

/**
 * Created with IDEA
 * author:foreign
 * Date:2019/9/30
 * Time:15:33
 */
public class ReflectionFk {
    public static void main(String[] args) throws NoSuchMethodException, NoSuchFieldException {
        Class clazz = PersonFk.class;
        //1 获取类上所有的注解
        Annotation[] annotations = clazz.getAnnotations();
        for (Annotation annotation : annotations) {
            if (annotation instanceof ClassAnnotation) {
                ClassAnnotation classAnnotation = (ClassAnnotation) annotation;
                System.out.println("类注解的name：" + classAnnotation.name());
                System.out.println("类注解的value：" + classAnnotation.value());
            }
        }
        //1.1 指定某个类上具体的注解
        Annotation annotation = clazz.getAnnotation(ClassAnnotation.class);
        if (annotation instanceof ClassAnnotation) {
            ClassAnnotation classAnnotation = (ClassAnnotation) annotation;
            System.out.println("类注解的name：" + classAnnotation.name());
            System.out.println("类注解的value：" + classAnnotation.value());
        }

        //2 获取方法上所有的注解
        Method getName = clazz.getMethod("getName");
        Annotation[] annotations1 = getName.getAnnotations();
        for (Annotation anno : annotations1) {
            if (anno instanceof MethodAnnotation) {
                MethodAnnotation methodAnnotation = (MethodAnnotation) anno;
                System.out.println("方法注解的name：" + methodAnnotation.name());
                System.out.println("方法注解的value：" + methodAnnotation.value());
            }
        }
        //2.1 指定某个方法上具体的注解
        Annotation annotation1 = getName.getAnnotation(MethodAnnotation.class);
        if (annotation1 instanceof MethodAnnotation) {
            MethodAnnotation methodAnnotation = (MethodAnnotation) annotation1;
            System.out.println("方法注解的name：" + methodAnnotation.name());
            System.out.println("方法注解的value：" + methodAnnotation.value());
        }

        //3 参数注解
        Method method = clazz.getMethod("setName", String.class);
        Annotation[][] parameterAnnotations = method.getParameterAnnotations();
        Class<?>[] parameterTypes = method.getParameterTypes();
        int i = 0;
        for (Annotation[] para : parameterAnnotations) {
            Class<?> parameterType = parameterTypes[i++];
            for (Annotation annotation2 : para) {
                if(annotation2 instanceof ParaAnnotation) {
                    ParaAnnotation paraAnnotation = (ParaAnnotation) annotation2;
                    System.out.println("方法参数注解的type：" + parameterType);
                    System.out.println("方法参数注解的name：" + paraAnnotation.name());
                    System.out.println("方法参数注解的value：" + paraAnnotation.value());
                }
            }
        }

        //4 变量注解
        Field name = clazz.getDeclaredField("name");
        Annotation[] annotations2 = name.getAnnotations();
        for (Annotation field : annotations2) {
            if(field instanceof FieldAnnotation) {
                FieldAnnotation fieldAnnotation = (FieldAnnotation) field;
                System.out.println("字段注解的name：" + fieldAnnotation.name());
                System.out.println("字段注解的value：" + fieldAnnotation.value());
            }
        }
    }
}

package com.foreign;

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

/**
 * Created with IDEA
 * author:foreign
 * Date:2019/9/30
 * Time:15:30
 */
//表示在运行时允许通过反射访问
@Retention(RetentionPolicy.RUNTIME)
//表示可以用在类，接口，枚举类型上
@Target(ElementType.TYPE)
public @interface ClassAnnotation {
    public String name();

    public String value();
}

package com.foreign;

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

/**
 * Created with IDEA
 * author:foreign
 * Date:2019/9/30
 * Time:16:00
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface FieldAnnotation {
    public String name();

    public String value();
}

package com.foreign;

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

/**
 * Created with IDEA
 * author:foreign
 * Date:2019/9/30
 * Time:15:43
 */
@Retention(RetentionPolicy.RUNTIME)
//表示可以用在方法上
@Target(ElementType.METHOD)
public @interface MethodAnnotation {
    public String name();

    public String value();
}

package com.foreign;

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

/**
 * Created with IDEA
 * author:foreign
 * Date:2019/9/30
 * Time:15:54
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface ParaAnnotation {
    public String name();

    public String value();
}

package com.foreign;

/**
 * Created with IDEA
 * author:foreign
 * Date:2019/9/30
 * Time:15:29
 */
@ClassAnnotation(name = "foreignClass", value = "foreignAnnotation")
public class PersonFk {
    @FieldAnnotation(name = "foreignField", value = "foreignAnnotation")
    private String name;
    private Integer age;
    private Boolean gender;
    public String desc;
    private String departmentId;

    public PersonFk(String name, Integer age, Boolean gender, String desc, String departmentId) {
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.desc = desc;
        this.departmentId = departmentId;
    }

    public PersonFk(String departmentId) {
        this.departmentId = departmentId;
    }

    public PersonFk() {
    }

    @MethodAnnotation(name = "foreignMethod", value = "foreignAnnotation")
    public String getName() {
        return name;
    }

    public void setName(@ParaAnnotation(name = "foreignPara", value = "foreignAnnotation") String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Boolean getGender() {
        return gender;
    }

    public void setGender(Boolean gender) {
        this.gender = gender;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    private String getDepartmentId() {
        return departmentId;
    }

    public void setDepartmentId(String departmentId) {
        this.departmentId = departmentId;
    }
}