caught NullPointerException in AutowiredAnnotationBeanPostProcessor.determineRequiredStatus [SPR-9316]

[spring-projects-issues]

Philippe Marschall opened SPR-9316 and commented

AutowiredAnnotationBeanPostProcessor.determineRequiredStatus uses ReflectionUtils.findMethod to look up a method named "required". If there is no such method then ReflectionUtils.findMethod returns null. However AutowiredAnnotationBeanPostProcessor.determineRequiredStatus never checks for null instead it directly passes the method to ReflectionUtils.invokeMethod which throws a NullPointerException which is then caught in a catch (Exception ex) block in AutowiredAnnotationBeanPostProcessor.determineRequiredStatus.

Annoations that don't have a method named "required" include @Inject @Value @Resource.

This is not so nice for several reasons:

• when you debug one of your own NullPointerExceptions and set an exception breakpoint on NullPointerException you end up in Spring code
• it uses NullPointerExceptions and catching them as part of normal control flow
• filling in the stack trace of an exception is slow

---

Affects: 3.1.1

Issue Links:

• AutowiredAnnotationBeanPostProcessor.determineRequiredStatus(Annotation) throws NullPointerException if method wasnt found. [SPR-9364] #14001 AutowiredAnnotationBeanPostProcessor.determineRequiredStatus(Annotation) throws NullPointerException if method wasnt found. ("is duplicated by")

Referenced from: commits 26ee0c4, 2624b90, 46bdb2d

[spring-projects-issues]

Philippe Marschall commented

Pull request is there #64

[spring-projects-issues]

Chris Beams commented

commit 2624b909060e0967e16771de7a35261decd5a4a9 (SPR-9316)
Author: Philippe Marschall <philippe.marschall@gmail.com>
Date:   Mon Apr 9 13:00:32 2012 +0200

    Avoid NPE in AutowiredAnnotationBeanPostProcessor
    
    Prior to this change, AABPP#determineRequiredStatus never checked the
    return value of ReflectionUtils#findMethod when searching for a
    '#required' attribute. This call returns null for annotations such as
    @Inject, @Value and @Resource, and subsequently causes a
    NullPointerException to be thrown when ReflectionUtils#invokeMethod is
    called. The NPE is caught immediately and #determineRequiredStatus
    returns defaulting to true, but this this approach is inefficient. It
    is also problematic for users who have set breakpoints on NPE -- they
    end up debugging into Spring internals, which is a false positive.
    
    This commit checks the return value of of ReflectionUtils#findMethod,
    and in the case of null, eagerly returns true.  There is no change to
    external behavior, simply a more efficient and debugging-friendly
    implementation.
    
    Existing test cases already cover this change, given that it is purely
    a refactoring.
    
    Issue: SPR-9316