Spring - what's wrong with my Autowiring?
I have this main spring application where the value of my field @Autowired
is zero in the output. What's wrong here?
package com.spring;
import org.springframework.beans.factory.annotation.Autowired;
public class HelloWorld {
private String message;
@Autowired
private Double pi;
public HelloWorld(String message){
this.message = message;
}
public void setMessage(String message){
this.message = message;
}
public void getMessage(){
System.out.println("Your Message : " + message);
System.out.println("autowired: "+pi);
}
}
spring.xml config file.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="pi" name="pi" class="java.lang.Double" autowire="byName">
<constructor-arg value="3.14"/>
</bean>
<bean id="helloWorld" class="com.spring.HelloWorld">
<constructor-arg ref="msg" />
</bean>
<bean id="msg" class="java.lang.String" >
<constructor-arg value="Hello World"/>
</bean>
</beans>
The class for the APP execution:
package com.tutorialspoint;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
HelloWorld hw = context.getBean(HelloWorld.class);
hw.getMessage();
System.out.println(context.getBean("msg"));
}
}
Output:
Your Message Hello World
autowired: null
Hello World
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3 answers
You need to add <context:annotation-config/>
to your spring.xml file that will validate spring annotations in your java files. Hope this helps.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:annotation-config />
<bean id="pi" name="pi" class="java.lang.Double">
<constructor-arg value="3.14" />
</bean>
<bean id="helloWorld" class="com.clsa.test.HelloWorld">
<constructor-arg ref="msg" />
</bean>
<bean id="msg" class="java.lang.String">
<constructor-arg value="Hello World" />
</bean>
</beans>
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