通过反射获取第一个父级的字段-解网

问：

我正在尝试获取对象的第一个父级的字段和值。我目前的代码是这样的：

Class<? extends Object> cls = obj.getClass();
Field[] fields = cls.getDeclaredFields();
for ( Field field : fields )
{
    String fieldName = field.getName();
    String fieldValue = field.get(obj);
}

我的类结构类似于：

class A
{
    int x;
}

class B extends A
{
    int y;
}

class C extends B
{
    int z;
}

现在，我将一个 C 对象传递给该方法，我想从 C 和 B 获取所有字段，而不是从 A 获取所有字段。有没有办法做到这一点（使用反射，我不想实现其他方法）？

Java 反射

public static void printFieldsFor(Class cls, Object obj) {
  Field[] fields = cls.getDeclaredFields();
  for ( Field field : fields ) {
    String fieldName = field.getName();
    String fieldValue = field.get(obj);
  }
}

printFieldsFor(object.getClass(), obj);
printFieldsFor(object.getClass().getSuperclass(), obj);

或使用循环

for(Class cls = object.getClass(); 
    cls!=null && cls!=A.class; 
    cls = cls.getSuperclass()) {
  for(Field field : cls.getDeclaredFields()) {
     String fieldName = field.getName();
     String fieldValue = field.get(obj);
     // do something with the field.
  }
}

28赞 DejanLekic 11/1/2011 #2

Luchian，请使用 getSuperclass（）方法获取对 Class 对象的引用，该对象表示相关对象的超类类型。之后，您将很容易像在示例中一样获取字段。

-4赞 Muhammad Suleman 4/24/2014 #3

您可以使用此代码从任何类中获取字段，而不管其父类或子类如何

for (Field field : YourClassName.class.getDeclaredFields()) {
  //fields
}

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * @author pablo.barbosa (2017-08-15)
 */
public class ReflectionUtil {

    /**
     * Hiding constructor. The methods are statics
     */
    private ReflectionUtil() {
        // Hiding constructor
    }

    public static List<Field> getInheritedDeclaredFields(Class<?> fromClass, Class<?> stopWhenClass) {
        if (stopWhenClass == null) {
            stopWhenClass = Object.class;
        }
        List<Field> fields = new ArrayList<>();
        List<Class<?>> classes = new ArrayList<>();

        Class<?> cls = fromClass;
        do {
            classes.add(cls);
            cls = cls.getSuperclass();
        } while (cls != null && !cls.equals(stopWhenClass));

        for (int i = classes.size() - 1; i >= 0; i--) {
            fields.addAll(Arrays.asList(classes.get(i).getDeclaredFields()));
        }

        return fields;
    }

    public static Field getInheritedDeclaredField(Class<?> fromClass, String fieldName, Class<?> stopWhenClass) throws NoSuchFieldException {
        if (stopWhenClass == null) {
            stopWhenClass = Object.class;
        }

        Class<?> cls = fromClass;
        do {
            Field field;
            try {
                field = cls.getDeclaredField(fieldName);
                if (field != null) {
                    return field;
                }
            } catch (NoSuchFieldException | SecurityException e) {
                // Nothing. We'll try to get field from superclass
            }
            cls = cls.getSuperclass();
        } while (cls != null && !cls.equals(stopWhenClass));

        // If we got here, we'll throw an exception
        throw new NoSuchFieldException(fieldName);
    }

    public static Object getInheritedDeclaredFieldValue(Object obj, String fieldName, Class<?> stopWhenClass) throws NoSuchFieldException, IllegalAccessException {
        Field field = getInheritedDeclaredField(obj.getClass(), fieldName, stopWhenClass);
        field.setAccessible(true);
        return field.get(obj);
    }

}

通过反射获取第一个父级的字段

Getting first parent's fields via reflection

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