Spring BeanUtils 属性拷贝遇 `IllegalArgumentException` 解决方案

Spring BeanUtils Copy Properties: Resolving IllegalArgumentException

Introduction

When working with Spring BeanUtils to copy properties between objects, you may encounter an IllegalArgumentException if the declaring class of a property differs between the source and target objects. This issue arises when the property is declared in a superclass in the source object but in a different class in the target object.

Causes and Resolution

The IllegalArgumentException occurs because BeanUtils uses reflection to copy properties. When the declaring class of a property changes, BeanUtils cannot find the setter method for the property in the target object. To resolve this issue, you can either:

• Move the property to the target class: Move the property declaration to the same class in both the source and target objects.
• Ensure property declaration consistency: Declare the property in the same class in both the source and target objects.

Additional Considerations

• Annotations: Ensure that both the source and target classes are properly annotated with @Data and @EqualsAndHashCode(callSuper = false) annotations.
• Default constructor: Verify that the target class has a default constructor.
• BeanUtils configuration: Check if the copyPropertyUtils bean is correctly configured and injected.

Alternative Approaches

• Different bean copy library: Consider using a different bean copy library, such as BeanUtils BeanUtils2 or Apache Commons BeanUtils.
• Bytecode inspection: Examine the bytecode of the target class to confirm that it is generated correctly and that the property is declared in the appropriate class.
• Stack trace analysis: Review the stack trace of the exception to identify any underlying issues.

Resources

• Spring BeanUtils BeanUtils2
• Apache Commons BeanUtils
• How to use BeanUtils in Spring Boot?

Conclusion

By understanding the causes and following the outlined resolution methods, you can effectively address the IllegalArgumentException when copying properties using Spring BeanUtils. Remember to verify class annotations, constructors, and BeanUtils configuration to ensure a seamless property copy process.

FAQs

1. Why does the IllegalArgumentException occur?
   It occurs when the property's declaring class differs between the source and target objects.

2. How can I resolve the exception?
   You can move the property to the target class or ensure the property is declared in the same class in both objects.

3. What are some alternative approaches?
   You can try using a different bean copy library or inspecting the bytecode of the target class.

4. Why is it important to have a default constructor in the target class?
   BeanUtils relies on reflection, which requires a default constructor to instantiate the target object.

5. Where can I find more information about BeanUtils?
   Refer to the provided resources for detailed documentation and examples.