CODEWITHSUNDEEP
javaspring
ovod
ovod

Reputation: 1178

Spring autowiring behaviour

I have the next simple application(class Message has only one method which prints incoming message and has no interest for the question):

package messager.spring;

public class User {
    private Messenger misiger;
    private String name;

    public User(String name) {
        this.name = name;
    }

    public void setMessenger(Messenger messinger) {
        this.misiger = messinger;
    }

    public void send(String mess) {
        String message = name + " sent message " + "'" + mess + "'";
        misiger.send(message);
    }

//  public String getname() {
//      return name;
//  }
}

Main class:

package messager.spring;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {
    public static void main(String[] args) {
          ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

          User user = (User) context.getBean("user");

          user.send("testing3...");
       }
}

Spring configuration 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-2.5.xsd">

    <bean id="user" class="messager.spring.User" autowire="byName">
        <constructor-arg type="java.lang.String" value="Vova2"/>
   </bean>

   <bean id="messenger" class="messager.spring.MobileMessenger"/>
</beans>

I used autowiring for class User autowiring Messanger class. According to documentation :

When ByName is used, it then tries to match and wire its properties with the beans defined by the same names in the configuration file. If matches are found, it will inject those beans otherwise, it will throw exceptions.

This configuration works but I dont understand why((( I dont have property with name messenger inside User class((( I changed it on purpose to misiger. And it still works. It seems that bean id directly depends not on property name, but on setter name!!! Is it so?

Upvotes: 1

Views: 163

Answers (2)

Milos Gregor
Milos Gregor

Reputation: 950

YES, you are right. As described here :

Spring will lowercase the first letter after “set” in the method name and use the rest of the method name as-is for deducing the property name.

So not the member variable but the setter defines the property name.

Upvotes: 3

Dave Newton
Dave Newton

Reputation: 160191

That's how JavaBeans work, by looking at naming conventions.

The underlying reference isn't necessarily relevant.

The name of your property is messenger because there's a getter called that.

Upvotes: 1

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