자바(Java) Reflect 예제

ReflectMethod.java

package reflect;

public class ReflectMethod {
 
   //field
   public String field;
 
   //constructor
   public ReflectMethod() {}

   public ReflectMethod(String field) {
      this.field = field;
   }
 
   //method
   public String getField() {
      System.out.println("call field : " + this.field);
      return this.field;
   }
   public void methodA() {
      System.out.println("call method A");
   }
   public void methodB(String str) {
      System.out.println("call method B : " + str);
   }
   public String methodC() {
      System.out.println("call method C");
      return "method C";
   }
}

ReflectMain.java

package reflect;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class ReflectMain {
   public static void main(String[] arguments) throws
                                         ClassNotFoundException, 
                                         InstantiationException, 
                                         IllegalAccessException, 
                                         SecurityException, 
                                         NoSuchMethodException, 
                                         IllegalArgumentException, 
                                         InvocationTargetException, 
                                         NoSuchFieldException {
  
  /* 
   * 원시형 클래스 타입
   * char : Character.TYPE
   * byte : Byte.TYPE
   * short : Short.TYPE
   * int : Integer.TYPE
   * long : Long.TYPE
   * float : Float.TYPE
   * double : Double.TYPE
   */
  
      //클래스 가져오기
      Class getClass1 = Class.forName("reflect.ReflectMethod");
      Class getClass2 = ReflectMethod.class;
      Class getClass3 = new ReflectMethod().getClass();
  
      //클래스 객체를 이용한 객체 생성

      //생성자에 인자가 없는 경우
      Object object1 = getClass1.newInstance();
      //생성자에 인자가 있을 경우
      Class[] constructorParamClass = new Class[] {String.class};
      Object[] constructorParamObject = new Object[] {"Reflect Test!!!"};
      Constructor constructor = getClass1.getConstructor(constructorParamClass);
      Object object2 = constructor.newInstance(constructorParamObject);

      //필드 값 가져오기
      Field field = getClass1.getField("field");
      Object fieldObject = field.get(object2);
  
      System.out.println(fieldObject);
  
      //메소드 호출
  
      //메소드에 인자가 없는 경우
      Method method1 = getClass1.getMethod("methodA");
      method1.invoke(object1);
      //메소드에 인자가 있을 경우
      Class[] methodParamClass = new Class[] {String.class};
      Object[] methodParamObject = new Object[] {"1 parameter"};
      Method method2 = getClass1.getMethod("methodB", methodParamClass);
      method2.invoke(object1, methodParamObject);
      //메소드에 리턴값이 있을 경우
      Method method3 = getClass1.getMethod("methodC");
      Object returnObject = method3.invoke(object1);
  
      System.out.println("methodC return value : " + returnObject);
   }
}

콘솔출력결과
Reflect Test!!!
call method A
call method B : 1 parameter
call method C
methodC return value : method C