Detailed explanation of FactoryBean in Spring

spring FactoryBean is to create complex beans. Generally, beans can be configured directly with xml. If a bean is created, it is difficult to configure with xml. At this time, you can consider using FactoryBean.

Examples are as follows:

1: Creating a Car class (for simplicity) generally cannot directly give the Car class. If so, it can be directly injected or a Car object. This is just for simplicity.

package ; 
 
public class Car { 
 private String make; 
 private int year; 
  public String getMake() { 
    return make; 
  } 
  public void setMake(String make) { 
     = make; 
  } 
  public int getYear() { 
    return year; 
  } 
  public void setYear(int year) { 
     = year; 
  } 
    
}

2: A FactoryBean implementation has created a car

package ; 
 
import ; 
 
public class MyCarFactoryBean implements FactoryBean<Car>{ 
   
  private String make; 
   
  private int year; 
 
  public void setMake(String make) { 
     = make; 
  } 
 
  public void setYear(int year) { 
     = year; 
  } 
 
  @Override 
  public Car getObject() throws Exception { 
    // TODO Auto-generated method stub 
     
    //Here is a complex car object created 
     // wouldn't be a very useful FactoryBean 
    // if we could simply instantiate the object! 
    Car car = new Car(); 
     
    if(year != 0){ 
      (); 
    } 
     
    if("make".equals(make)){ 
      ("we are making bla bla bla"); 
    }else{ 
      (); 
    } 
     
    return car; 
  } 
 
  @Override 
  public Class<?> getObjectType() { 
    // TODO Auto-generated method stub 
    return ; 
  } 
 
  @Override 
  public boolean isSingleton() { 
    // TODO Auto-generated method stub 
    return false; 
  } 
 
}

The above is too simple to create a car. If it is too simple, there is no need to create it with FactoryBean. It can be written more complicatedly.

3: Person quotes a car

package ; 
 
public class Person { 
  
  private Car car; 
 
  public Car getCar() { 
    return car; 
  } 
 
  public void setCar(Car car) { 
     = car; 
  } 
   
  public String toString(){ 
     
    return ()+"::::"+(); 
  } 
}

4: Configure the reference xml format:

<bean  class=""> 
  <property name="make" value="makeing car"/> 
  <property name="year" value="123"/> 
</bean> 
 
<bean  class=""> 
 
<property name="car" ref="car"/> 
 
</bean>

5: Write tests:

package ; 
 
import ; 
import ; 
 
public class MainTest { 
 public static void main(String[] args) { 
   
   ApplicationContext context = new ClassPathXmlApplicationContext("resource/"); 
    
 Person person =  (Person)("person"); 
    
   // Car car =  (Car)("car"); 
    
  // (car); 
  (person); 
} 
}

Test results making car::::123

Create a car successfully with FactoryBean

Just to illustrate the thought. Because this interface is too important. There are many classes in Spring that implement this interface.

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