Example On Spring Autowiring byName

In this case, spring framework attempts to find out a bean in the configuration file, whose id is matching with the property name to be wired.  If a bean found with id as property name then that class object will be injected into that property by calling setter injection.  If no id is found then that property remains un-wired, but never throws any exception.

Example On Autowiring byName

public class MyBean
{
     private DemoBean db;
     public void setDb(DemoBean db)
     {
        this.db=db;
     }
}

In the xml file

<beans>
  <bean id="id1" class="MyBean" autowire="byName" />
  <bean id="db" class="DemoBean" />  
</beans>

Explanation:

See line number 3 in MyBean, our class depends on DemoBean class object right,  now see in the xml file line number 2 we have given autowire=”byName“, means when ever spring container notice autowire=”byName” then it will verifies whether the id in xml file is matching with the property name in the MyBean or not, if yes it will wired  automatically else unwired

Am giving one figure to make you understand better 🙂

Complete Example

Files required…

• Book.java
• Categories.java
• ClientLogic.java
• spconfig.xml

Book.java

package java4s;
public class Book {

	private String bookname;
	private int bookprice;

	public String getBookname() {
		return bookname;
	}
	public void setBookname(String bookname) {
		this.bookname = bookname;
	}
	public int getBookprice() {
		return bookprice;
	}
	public void setBookprice(int bookprice) {
		this.bookprice = bookprice;
	}	   

}

Categories.java

package java4s;
public class Categories {

	private String name;
	private Book bk;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Book getBk() {
		return bk;
	}

	public void setBk(Book bk) {
		this.bk = bk;
	}

	public void show()
	{
		System.out.println("Categories name :"+name);
		System.out.println("Book name :"+bk.getBookname()+" and Book Price :"+bk.getBookprice());
	}

}

ClientLogic.java

package java4s;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class ClientLogic {

	public static void main(String[] args)
	{
		Resource res = new ClassPathResource("spconfig.xml");
		BeanFactory factory = new XmlBeanFactory(res);

		Object o = factory.getBean("id1");
		Categories wb = (Categories)o;

		wb.show();

	}

}

spconfig.xml

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN"
"http://www.springframework.org/dtd/spring-beans-2.0.dtd">

<beans>
  <bean id="id1" class="java4s.Categories" autowire="byName">
        <property name="name" value="General Books" />
  </bean>
  <bean id="bk" class="java4s.Book">
        <property name="bookname" value="The Kids" />
        <property name="bookprice" value="300" />
  </bean>
</beans>

Notes: We called id1 from ClientLogic.java [line number 15], and in spconfig.xml we have written autowire=byName, so first it will checks for the class with id name bk [as we have written private Book bk in Categories.java ] and inserts bk class [ jaa4s.Book ] properties into that object and then injects value “General Books” into name property of Categories class.

Finally in ClientLogic.java we used to type cast to get our output.

Output

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::. About the Author .::
		Sivateja Kandula - Java/J2EE Full Stack Developer Founder of Java4s - Get It Yourself, A popular Java/J2EE Programming Blog, Love Java and UI frameworks. You can sign-up for the Email Newsletter for your daily dose of Java tutorials.