标签：style default public div policy use end 如何 pen
如何通过注解值得到对应成员变量？
自定义注解
@Inherited @Target(ElementType.FIELD) @Retention(RetentionPolicy.RUNTIME) public @interface Index { String name() default ""; }
定义User类
import lombok.Getter; import lombok.Setter; @Setter @Getter public class User { @Index(name = "userNo") private int userId; @Index(name = "Name") private String userName; }
其中lombok的依赖配置为
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.2</version>
</dependency>
测试注解
public class UserTest { private void test1() { Class<User> clazz = User.class; Field[] fields = clazz.getDeclaredFields(); List<Field> result = new ArrayList<>(); for (Field field : fields){ if(field.getAnnotation(Index.class)!=null) { result.add(field); } } for(Field list:result){ System.out.println("被注解的字段为:" + list.getName()); } } private void test2() { Class<User> clazz = User.class; Field[] fields = clazz.getDeclaredFields(); List<String> result = new ArrayList<>(); for (Field field : fields){ if(field.getAnnotation(Index.class)!=null) { result.add(field.getAnnotation(Index.class).name()); } } for(String list:result){ System.out.println("注解的字段为:" + list); } } public static void main(String[] args) { UserTest userTest = new UserTest(); userTest.test1(); userTest.test2(); } }
结果
被注解的字段为:userId 被注解的字段为:userName 注解的字段为:userNo 注解的字段为:Name
private void test3() { Map<String, String> annotation2Field = new HashMap<>(); Class<User> clazz = User.class; Field[] fields = clazz.getDeclaredFields(); List<String> result = new ArrayList<>(); for (Field field : fields){ if(field.getAnnotation(Index.class)!=null) { result.add(field.getAnnotation(Index.class).name()); annotation2Field.put(field.getAnnotation(Index.class).name(), field.getName()); } } annotation2Field.forEach((k, v)-> System.out.println(k + ":" + v)); }
标签：style default public div policy use end 如何 pen
原文地址：https://www.cnblogs.com/kaituorensheng/p/9813664.html
