我创建了 2 个简单的类。一个类的构造函数被注释为@Autowired。它接受另一个类的对象。但是这段代码失败了。
类:- 1)SimpleBean.java
@Configuration
public class SimpleBean {
InnerBean prop1;
public InnerBean getProp1() {
return prop1;
}
public void setProp1( InnerBean prop1) {
System.out.println("inside setProp1 input inner's property is "
+ prop1.getSimpleProp1());
this.prop1 = prop1;
}
@Autowired(required=true)
public SimpleBean(InnerBean prop1) {
super();
System.out.println("inside SimpleBean constructor inner's property is "
+ prop1.getSimpleProp1());
this.prop1 = prop1;
}
}
2) 内部.java
@Configuration
public class InnerBean {
String simpleProp1;
public String getSimpleProp1() {
return simpleProp1;
}
public void setSimpleProp1(String simpleProp1) {
this.simpleProp1 = simpleProp1;
}
}
当我尝试加载 ApplicationConext
ApplicationContext acnxt = new AnnotationConfigApplicationContext("com.domain");
它给出以下错误:-
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'simpleBean' defined in file [C:\Users\owner\Documents\Java Project\MyWorkSpace\springMVCSecond\WebContent\WEB-INF\classes\com\domain\SimpleBean.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.domain.SimpleBean$$EnhancerByCGLIB$$4bc418be]: No default constructor found; nested exception is java.lang.NoSuchMethodException: com.domain.SimpleBean$$EnhancerByCGLIB$$4bc418be.<init>()
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:965)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:911)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init>(AnnotationConfigApplicationContext.java:75)
at com.test.SpringAnnotationTest.main(SpringAnnotationTest.java:12)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.domain.SimpleBean$$EnhancerByCGLIB$$4bc418be]: No default constructor found; nested exception is java.lang.NoSuchMethodException: com.domain.SimpleBean$$EnhancerByCGLIB$$4bc418be.<init>()
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:70)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:958)
... 12 more
Caused by: java.lang.NoSuchMethodException: com.domain.SimpleBean$$EnhancerByCGLIB$$4bc418be.<init>()
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.getDeclaredConstructor(Unknown Source)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:65)
... 13 more
如果我在 SimpleBean 类中引入无参数构造函数。它不会给出错误。但这并没有给我 SimpleBean 的预填充对象(如在 XML 配置中使用 <constructor-arg > )。那么在使用注解时,是否必须有无参数构造函数?什么是合适的出路?