获取注解信息

获取注解信息

package other;

import java.lang.annotation.*;
import java.lang.reflect.Field;

public class Test08 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException {
        Class c1 = Class.forName("other.Student2");

        //通过反射获得注解
        Annotation[] annotations = c1.getAnnotations();
        for (Annotation annotation : annotations) {
            System.out.println(annotation);
        }

        //获得注解的value的值
//        Tablexie tablexie = (Tablexie)c1.getAnnotations(Tablexie.class);
//        Tablexie.value();
//        System.out.println(value);

        //获得类指定的注解
        Field f = c1.getDeclaredField("name");
        Fieldxie annotation = f.getAnnotation(Fieldxie.class);
        System.out.println(annotation.columnName());
        System.out.println(annotation.length());
        System.out.println(annotation.type());
    }
}
@Tablexie("db_student")
class Student2{

    @Fieldxie(columnName = "db_id",type = "int",length = 10)
    private int id;
    @Fieldxie(columnName = "db_age",type = "int",length = 10)
    private int age;
    @Fieldxie(columnName = "db_name",type = "varchar",length = 3)
    private String name;

    public Student2() {
    }

    public Student2(int id, int age, String name) {
        this.id = id;
        this.age = age;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getAge() {
        return age;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

//类名的注解
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@interface Tablexie{
    String value();
}
//属性的注解
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@interface Fieldxie{
    String columnName();
    String type();
    int length();
}