Reflection

 

1. 클래스 얻기

 

• Object.getClass()

UserVo vo = new UserVo();
System.out.println(vo.getClass());

• .class

System.out.println(UserVo.class);

• Class.forName("")

try {
	System.out.println(Class.forName("vo.UserVo"));
} catch (ClassNotFoundException e) {
	e.printStackTrace();
}

 

 

2. private field 셋팅

public class UserVo {

    private String name;

    public String getName() {
        return name;
    }

}

public static void main(String[] args) {
    
    try {
        
        Class clazz = Class.forName("UserVo");
        Field field = clazz.getDeclaredField("name");
        field.setAccessible(true);

        UserVo vo = (UserVo) clazz.newInstance();
        field.set(vo, "TEST");

        String value = (String) vo.getName();
        System.out.println(value);

    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (InstantiationException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    }
    
}

 

    

3. private method 호출

public class UserVo {

    private String getName() {
        return "TEST";
    }

}

public static void main(String[] args) {
    try {

        Class clazz = Class.forName("UserVo");
        Method method = clazz.getDeclaredMethod("getName");
        method.setAccessible(true);

        UserVo vo = (UserVo) clazz.newInstance();
        String value = (String) method.invoke(vo);
        System.out.println(value);

    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (InstantiationException e) {
        e.printStackTrace();
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        e.printStackTrace();
    }
}

 

 

4. private constructor 인스턴스 만들기

public class UserVo {
    
    private UserVo() {
    }
    
}​

public static void main(String[] args) {
    try {

        Class clazz = Class.forName("UserVo");
        Constructor constructor = clazz.getDeclaredConstructor();
        constructor.setAccessible(true);
        UserVo vo = (UserVo)constructor.newInstance();
        System.out.println(vo);

    } catch (Exception e) {
        e.printStackTrace();
    }
}