Autowiring : Example

Bean classes

class A {

  @Override

  public String toString() {

    return getClass().getName();

  }

}

class B {

  @Override

  public String toString() {

    return getClass().getName();

  }

}

class MyClass {

  private B B;

  private B B2;

  private A A;

  public MyClass() {

    System.out.println("MyClass()");

  }

  public MyClass(B B) {

    System.out.println("MyClass(B)");

    this.B = B;

  }

  public MyClass(B B, A A) {

    System.out.println("MyClass(B, A)");

    this.B = B;

    this.A = A;

  }

  public void setDependency(A A) {

    System.out.println("MyClass.setDependency(A)");

    this.A = A;

  }

  public void setB(B B) {

    System.out.println("MyClass.setB(B)");

    this.B = B;

  }

  public void setB2(B B2) {

    System.out.println("MyClass.setB2(B)");

    this.B2 = B2;

  }

  public void setA(A A) {

    System.out.println("MyClass.setA(A)");

    this.A = A;

  }

  @Override

  public String toString() {

    final StringBuilder sb = new StringBuilder();

    sb.append("MyClass");

    sb.append("{B=").append(B);

    sb.append(", B2=").append(B2);

    sb.append(", A=").append(A);

    sb.append('}');

    return sb.toString();

  }

}

Bean definition in Spring XML

<?xml version="1.0" encoding="UTF-8"?>

<beans ...>

    <bean id="a" class="A"/>

    <bean id="b" class="B"/>

    <bean id="byName" autowire="byName" class="MyClass"/>

    <bean id="byType" autowire="byType" class="MyClass"/>

    <bean id="constructor" autowire="constructor" class="MyClass"/>

    <bean id="autodetect" autowire="autodetect" class="MyClass"/>

</beans>

Write a main program to use beans

XmlBeanFactory bf = new XmlBeanFactory(

                       new ClassPathResource("context.xml"));

System.out.println("byName:");

System.out.println(bf.getBean("byName"));

System.out.println("byType:");

System.out.println(bf.getBean("byType"));

System.out.println("constructor:");

System.out.println(bf.getBean("constructor"));

System.out.println("autodetect:");

System.out.println(bf.getBean("autodetect"));