用反射设置私有字段值 [英] Set private field value with reflection

问题描述

我有2个班级:Father和Child

public class Father implements Serializable, JSONInterface {

    private String a_field;

    //setter and getter here

}

public class Child extends Father {
    //empty class
}

通过反射，我想在Child类中设置a_field:

With reflection I want to set a_field in Child class:

Class<?> clazz = Class.forName("Child");
Object cc = clazz.newInstance();

Field f1 = cc.getClass().getField("a_field");
f1.set(cc, "reflecting on life");
String str1 = (String) f1.get(cc.getClass());
System.out.println("field: " + str1);

但我有一个例外:

线程"main"中的异常java.lang.NoSuchFieldException:a_field

Exception in thread "main" java.lang.NoSuchFieldException: a_field

但是，如果我尝试:

Child child = new Child();
child.setA_field("123");

有效.

使用setter方法，我有同样的问题:

Using setter method I have same problem:

method = cc.getClass().getMethod("setA_field");
method.invoke(cc, new Object[] { "aaaaaaaaaaaaaa" });

推荐答案

要访问私有字段，您需要将Field::setAccessible设置为true.您可以离开超类领域.这段代码有效:

To access a private field you need to set Field::setAccessible to true. You can pull the field off the super class. This code works:

Class<?> clazz = Child.class;
Object cc = clazz.newInstance();

Field f1 = cc.getClass().getSuperclass().getDeclaredField("a_field");
f1.setAccessible(true);
f1.set(cc, "reflecting on life");
String str1 = (String) f1.get(cc);
System.out.println("field: " + str1);

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