In our example, both the getDeclaredField() method and the setAccessible() method contain an inner security check that will throw a SecurityException if called by a code that is not authorized by the securitymanager. By default code using reflection needs particular security permissions. The only way to prevent reflection is to use a securitymanager. However, an "evil" code can also use it to break the security of your application and access and modify any field and a lot more things (invoke any methods, list all class content, etc). Reflection is a very powerful feature and a lot of Java frameworks use it. The only include that is needed for this article codes is :
This is just a little part of the enormous possibilities of reflection, the goal here is to show that reflection can "break" classic keyword security. The classes allows you do do a lot more things than just access to class fields. Use reflection to modify any class/object field. This package provides objects that can be used to list any fields inside a class, invoke any class methods or access and modify any fields, and when I say any I mean all of them, even private ones. Reflection is a direct part of the Java language. Reflection is a Java feature that allows a code to examine itself dynamically and modify its references and properties at runtime. These examples shows that Java data access security is guaranteed by the language keywords, however this statement is not true because of Java "reflection". In this example the field "name" can only be accessed by another code in the same object, and it has the "final" keyword so it cannot be modified once it is set (a real Java constant has both the keywords "static" and "final"). The field called "state" is a class variable, with the given keywords, it should only be accessible by other instance objects of the same class. This work is licensed under a Creative Commons Attribution 4.0 International License.įor most Java developers, Java security comes from the use of keywords such as "private, protected, or final". License : Copyright Emeric Nasi, some rights reserved
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