注解结合反射,天衣无缝
2022/7/23 23:24:08
本文主要是介绍注解结合反射,天衣无缝,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
请看示例代码
package com.xxd.modules.util; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import lombok.ToString; import java.lang.annotation.*; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; public class RefTest { public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException, NoSuchFieldException { Class aClass = Class.forName("com.xxd.modules.util.Student"); Student student = (Student) aClass.newInstance(); // 通过反射执行方法 Method method = aClass.getDeclaredMethod("setName", String.class); method.invoke(student, "润哥"); System.out.println(student); // 通过反射获取注解 Annotation[] annotations = aClass.getAnnotations(); for (Annotation annotation : annotations) { System.out.println(annotation); } // 获取指定注解的值 TableRun tableRun = (TableRun) aClass.getAnnotation(TableRun.class); String value = tableRun.value(); System.out.println(value); // 获取属性中指定的注解 Field field = aClass.getDeclaredField("name"); FieldRun fieldRun = field.getAnnotation(FieldRun.class); System.out.println(fieldRun.columnName()); System.out.println(fieldRun.type()); System.out.println(fieldRun.length()); } } @Data @AllArgsConstructor @NoArgsConstructor @ToString @TableRun("db_student") class Student { @FieldRun(columnName = "id", type = "int", length = 8) private int id; @FieldRun(columnName = "age", type = "int", length = 8) private int age; @FieldRun(columnName = "name", type = "varchar", length = 8) private String name; } // 类名的注解 @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @interface TableRun { String value(); } // 属性的注解 @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.FIELD) @Documented @interface FieldRun { String columnName(); String type(); int length(); }
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