使用Java Annotation进行参数验证

Question

I understand, in Java we have parameters validation solution. I believe JAX-RS has various annotations both for validation and data extraction. My question is, if I want to implement my own parameter validation class for a standalone Java application, how would I make sure that a method is executed only when its parameters have been validated? I am using Reflection to spot parameters with @LowerCaseCheck and then performing validation on it, but not sure where to place this validation code.

public void print(@LowerCaseCheck String lowerCaseString) {
  ....
}

Answer 1

您需要更改方法的字节代码以执行检查（或调用执行检查的方法）最简单的方法可能是使用AspectJ等面向Aspect的库。

Answer 2

Look at gag for an example of a library that does what you're looking for. It uses the asm bytecode manipulation library to insert validation checks at the start of annotated methods.

Answer 3

Cant'you use Bean Validation (JSR-303) to solve your problem ? the @Pattern(regexp) annotation seems to do just what you need.

public void print(@Pattern(regexp = "^[a-z]*$") String lowerCaseString) {
  ....
}