027.2 반사 기술 동적 획득 필드 및 방법

String className = "cn.itcast.domain.Person";
Class clazz = Class.forName(className);

String fieldName = "age";

// age 。
//        Field field = clazz.getField(fieldName);// 。
Field field = clazz.getDeclaredField(fieldName);

//        getXXX: 。
//        getDeclaredXXX: 。
//        System.out.println(field);

// ， 。
Object obj = clazz.newInstance();


// AccessiableObject 。setAccessiable(true);
field.setAccessible(true);// ， 。 。
field.set(obj, 30);//IllegalAccessException:age 。

System.out.println(field.get(obj));

##Person.java
…
public void show(String name,int age){
    System.out.println("show run...name="+name+",age="+age);
}

public static void staticShow(){
    System.out.println("static show run");
}

...

##
public static void getMethodDemo2() throws Exception {
    String className = "cn.itcast.domain.Person";
    Class clazz = Class.forName(className);
    String methodName = "staticShow";
    
    Method method = clazz.getMethod(methodName, null);
    method.invoke(null, null);
}

public static void getMethodDemo() throws Exception {
    
    String className = "cn.itcast.domain.Person";
    Class clazz = Class.forName(className);
    
    String methodName = "show";
    
    Method method = clazz.getMethod(methodName, String.class,int.class);
    Object obj = clazz.newInstance();
    method.invoke(obj, "wangcai",20);
}