Using properties file for defining class dependency

[Tai Kings]

Hi All,

I am new to Spring, and following the examples of Spring book, but have problem about BeanFactory using Properties file. Please help
- Posted 3 files (complete code) and 1 screen capture about error message.
- Environment : J2SE 6 , spring-framework-3.0.5.RELEASE, Eclipse Java EE IDE for Web Developers.
- FYI, in previous lab example, can successfully use xml configuration file for definiting class dependency, but failed when using property file (non-xml file)

File1 : PropertiesDemo.java

package onlyfun.caterpillar; 

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.support.PropertiesBeanDefinitionReader; 
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class PropertiesDemo { 
    public static void main(String[] args) { 
        
    	BeanDefinitionRegistry reg = 
            new DefaultListableBeanFactory(); 
        PropertiesBeanDefinitionReader reader = 
            new PropertiesBeanDefinitionReader(reg); 
        reader.loadBeanDefinitions(
                new ClassPathResource("beans-config.properties")); 
        
        BeanFactory factory = (BeanFactory) reg; 
        System.out.println(factory.containsBean("helloBean"));
        System.out.println(factory.toString());
        H2 hello = (H2) factory.getBean("helloBean");
        		      
         
    } 
}

File 2 : H2.java

package onlyfun.caterpillar; 

public class H2 { 
    private String helloWord;
    
    public H2() {
    }
    
    public void setHelloWord(String helloWord) { 
        this.helloWord = helloWord;
    } 
    public String getHelloWord() { 
        return helloWord; 
    }
}

File 3 : beans-config.properties

helloBean.class=onlyfun.caterpillar.H2
helloBean.helloWord=Welcome!

Screen capture

true
org.springframework.beans.factory.support.DefaultListableBeanFactory@b09e89: defining beans [helloBean]; root of factory hierarchy
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloBean': Instantiation of bean failed; nested exception is java.lang.IllegalStateException: No bean class specified on bean definition
	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:291)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
	at onlyfun.caterpillar.PropertiesDemo.main(PropertiesDemo.java:23)
Caused by: java.lang.IllegalStateException: No bean class specified on bean definition
	at org.springframework.beans.factory.support.AbstractBeanDefinition.getBeanClass(AbstractBeanDefinition.java:372)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:52)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:958)
	... 8 more

Many Many Thanks!

TaiKS

[Mark Spritzler]

If you are using Spring 3.0.5, why are you using the older BeanFactory class instead of using ApplicationContext?

Mark

[Tommy Delson]

If looked the error message carefully and pay attention to error you'll see that it tell
you clearly that you didn't specified the class name on the bean definition.

For instance,

"Caused by: java.lang.IllegalStateException: No bean class specified on bean definition"

Based on this I error I can tell what' wrong with the code simply in the "beans-config.properties"
file you didn't configure it correctly.

Problems:
File 3 : beans-config.properties
helloBean.class=onlyfun.caterpillar.H2 //The problem is here...you specified the wrong bean name.
helloBean.helloWord=Welcome!

Solutions:

"H2" is what you need instead of the whole package name prefix the class name.

helloBean.class = H2 //bean is of class H2

Make a change, test it, and let us know if that fix the problem. I can't confirm
100% that will fix the problem unless it being tested.