通过反射访问Java中的私有变量
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Accessing private variables in Java via reflection
提问by dcp
I'm trying to write a method that will get a private field in a class using reflection.
我正在尝试编写一个方法，该方法将使用反射在类中获取私有字段。
Here's my class (simplified for this example):
这是我的课程（针对此示例进行了简化）：
public class SomeClass {
private int myField;
public SomeClass() {
myField = 42;
}
public static Object getInstanceField(Object instance, String fieldName) throws Throwable {
Field field = instance.getClass().getDeclaredField(fieldName);
return field.get(instance);
}
}
So say I do this:
所以说我这样做：
SomeClass c = new SomeClass();
Object val = SomeClass.getInstanceField(c, "myField");
I'm getting an IllegalAccessExceptionbecause myFieldis private. Is there a way to get/set private variables using reflection? (I've done it in C#, but this is the first time I've tried it in Java). If you're wondering why there is the need to do such madness :), it's because sometimes during unit testing it's handy to set private variables to bogus values for failure testing, etc.
我得到一个IllegalAccessException因为myField是私人的。有没有办法使用反射来获取/设置私有变量？（我已经在 C# 中完成了它，但这是我第一次在 Java 中尝试它）。如果您想知道为什么需要这样做:)，那是因为有时在单元测试期间，将私有变量设置为用于故障测试等的虚假值很方便。
采纳答案by dcp
Figured it out. Need
弄清楚了。需要
field.setAccessible(true);
