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Java 反射机制的缺点有哪些


反射的用途 Uses of Reflection

Reflection is commonly used by programs which require the ability to examine or modify the
runtime behavior of applications running in the Java virtual machine. This is a relatively advanced
feature and should be used only by developers who have a strong grasp of the fundamentals of the language. With that caveat in mind, reflection is a powerful technique and can enable applications to perform operations which would otherwise be impossible.

反射的缺点 Drawbacks of Reflection

Reflection is powerful, but should not be used indiscriminately. If it is possible to perform an
operation without using reflection, then it is preferable to avoid using it. The following concerns
should be kept in mind when accessing code via reflection.

性能第一 Performance Overhead

Because reflection involves types that are dynamically resolved, certain Java virtual machine
optimizations can not be performed. Consequently, reflective operations have slower performance
than their non-reflective counterparts, and should be avoided in sections of code which are called
frequently in performance-sensitive applications.
反射包括了一些动态类型,所以 JVM 无法对这些代码进行优化。因此,反射操作的效
率要比那些非反射操作低得多。我们应该避免在经常被 执行的代码或对性能要求很高的程

安全限制 Security Restrictions

Reflection requires a runtime permission which may not be present when running under a
security manager. This is in an important consideration for code which has to run in a restricted
security context, such as in an Applet.
安全限制的环境中运行,如 Applet,那么这就是个问题了。

内部暴露 Exposure of Internals

Since reflection allows code to perform operations that would be illegal in non-reflective
code, such as accessing private fields and methods, the use of reflection can result in
unexpected side-effects, which may render code dysfunctional and may destroy portability.
Reflective code breaks abstractions and therefore may change behavior with upgrades of the