Example On Spring Autowiring byType

Let us see an application on Spring Autowiring with byType, let me clear this confusion about byType,byName…

Avoid byType – byName confusion

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

Example On Spring Autowiring byType

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="byType">
      <property name="name" value="General Books" />
  </bean>
  <bean id="SomeThing" 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=byType, so first spring container will checks for the bean with class attribute Book [as autowire=byType and we have written private Book bk in Categories.java  ] and then inserts Book class properties into Book class object [ jav4s.Book ] and gives this book class object to Categories then injects value “General Books” into name property of Categories class.  [ read slowly 2 or 3 times, nothing is there friends ]

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.