Spring Autowiring only works with Interface

java spring autowired
Chaitanya picture Chaitanya · Jun 28, 2011 · Viewed 18.4k times · Source

I am quite new to spring framework and came across the following issue.

I have an interface ClassA, which is implemented by classed ClassA1 and ClassA2.

I have the following bean definition added to applicationContext.xml

<bean id="class1" class="com.abc.ClassA1" />
<bean id="class2" class="com.abc.ClassA2" />

I would like to Autowire both the implementation classes as below.

@Autowired
private ClassA1 classA1;

@Autowired
private ClassA2 classA2;

The above code is throwing error as

Could not autowrite to field: com.abc.ClassA1 com.abc.SomeClass.classA1; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.abc.ClassA1]

But, if I change the autowiring to interface as below:

@Autowired
ClassA classA1;

Then ClassA1 is autowired to the variable. I am clueless on how can I autowire a variable to ClassA2.

Answer

Tarlog picture Tarlog · Jun 28, 2011

For some reason your classes are proxied by Spring. There many reasons why this can happen. For example if you use JPA, or AOP the original class is proxied.

If a class implements an interface, proxy means Dynamic Proxy. So basically a new class is created in runtime that implements the interfaces but does not inherit from the original class. Therefore the autowiring to the original class doesn't work.

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