Example On Spring Autowiring by Constructor

Actually Spring Autowiring by constructor is similar to spring autowiring byType [ internally it will considers as byType only ]  but with little difference, in byType we used setter injection here we have to use constructor injection 🙂  nothing more than that.

Friends am using same application to show the difference between byName, byType, constructor, autodetect to avoid confusions [ Out put is same for all these 4 applications 😉 ]

Example On Spring Autowiring Constructor

Files required…

• Book.java
• ClientLogic.java
• Categories.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 Categories(Book bk)
    {
           this.bk=bk;
    }

    public String getName() {
        return name;
    }

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

    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="constructor">
      <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:  Friends am not explaining this program, as i told you earlier Spring Autowiring constructor is similar to Spring Autowiring byType but here we use constructor injection, please refer byType if you still have any doubts.

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.