代码如下
package com.loubin;import java.lang.annotation.*; import java.lang.reflect.Constructor; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method;public class Main {public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {User user = new User("张三", 18);Class c = user.getClass();UserTable userTable = (UserTable) c.getAnnotation(UserTable.class);String tableName = userTable.tableName();System.out.println(tableName);Field fieldName = c.getDeclaredField("name");UserColumn userColumn = fieldName.getAnnotation(UserColumn.class);System.out.println(userColumn.columnName());System.out.println(userColumn.columnType());System.out.println(userColumn.columnLength());// Class c = User.class; // String name = c.getName(); // System.out.println(name); // System.out.println("获取所有属性-------------------------------"); // Field[] fields = c.getDeclaredFields(); // for (Field field : fields) { // System.out.println(field.getName()); // } // System.out.println("获取指定属性-----------------------------------"); // Field field = c.getDeclaredField("name"); // System.out.println(field.getName()); // System.out.println("获取所有方法----------------------------------"); // Method[] methods = c.getDeclaredMethods(); // for (Method method : methods) { // System.out.println(method.getName()); // } // System.out.println("获取指定方法----------------------------------"); // Method method = c.getDeclaredMethod("getName"); // System.out.println(method.getName()); // System.out.println("获取无参构造器------------------------------------"); // Constructor constructor = c.getDeclaredConstructor(); // System.out.println(constructor.getName()); // System.out.println("获取有参构造器-----------------------------------"); // Constructor constructor1 = c.getDeclaredConstructor(String.class, int.class); } }@UserTable(tableName = "db_user") class User{@UserColumn(columnName = "db_name", columnType = "string", columnLength = 20)String name;@UserColumn(columnName = "db_age", columnType = "int", columnLength = 20)int age;public User() {}public User(String name, int age) {this.name = name;this.age = age;}public void shout(String name){System.out.println("是谁叫了一下" + name);}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;}}@Target(value = ElementType.TYPE) @Retention(value = RetentionPolicy.RUNTIME) @Documented @Inherited @interface UserTable{String tableName(); }@Target(value = ElementType.FIELD) @Retention(value = RetentionPolicy.RUNTIME) @interface UserColumn{String columnName();String columnType();int columnLength(); }
测试结果如下
