详解Spring中的FactoryBean

spring  FactoryBean 是创建 复杂的bean,一般的bean 直接用xml配置即可,如果一个bean的创建过程中涉及到很多其他的bean 和复杂的逻辑,用xml配置比较困难,这时可以考虑用FactoryBean

例子如下:

1:创建一个Car类(是为了简便)一般不能直接给出Car类,如果是这样直接注入就可以或者Car对象了,这里只是为了简便。

package com.myapp.core.factorybean; 
 
public class Car { 
 private String make; 
 private int year; 
  public String getMake() { 
    return make; 
  } 
  public void setMake(String make) { 
    this.make = make; 
  } 
  public int getYear() { 
    return year; 
  } 
  public void setYear(int year) { 
    this.year = year; 
  } 
    
}

2:一个FactoryBean的实现拥有创建car

package com.myapp.core.factorybean; 
 
import org.springframework.beans.factory.FactoryBean; 
 
public class MyCarFactoryBean implements FactoryBean{ 
   
  private String make; 
   
  private int year; 
 
  public void setMake(String make) { 
    this.make = make; 
  } 
 
  public void setYear(int year) { 
    this.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){ 
      car.setYear(this.year); 
    } 
     
    if("make".equals(make)){ 
      car.setMake("we are making bla bla bla"); 
    }else{ 
      car.setMake(this.make); 
    } 
     
    return car; 
  } 
 
  @Override 
  public Class getObjectType() { 
    // TODO Auto-generated method stub 
    return Car.class; 
  } 
 
  @Override 
  public boolean isSingleton() { 
    // TODO Auto-generated method stub 
    return false; 
  } 
 
} 

以上中创建car太简单了,如果太简单就没有必要用FactoryBean创建了,可以写的复杂些。

3:Person 引用一个car

package com.myapp.core.factorybean; 
 
public class Person { 
  
  private Car car; 
 
  public Car getCar() { 
    return car; 
  } 
 
  public void setCar(Car car) { 
    this.car = car; 
  } 
   
  public String toString(){ 
     
    return car.getMake()+"::::"+car.getYear(); 
  } 
} 

4:配置引用xml格式:

 
   
   
 
 
 
 
 
 
 

5:编写测试类测试:

package com.myapp.core.factorybean; 
 
import org.springframework.context.ApplicationContext; 
import org.springframework.context.support.ClassPathXmlApplicationContext; 
 
public class MainTest { 
 public static void main(String[] args) { 
   
   ApplicationContext context = new ClassPathXmlApplicationContext("resource/others.xml"); 
    
 Person person =  (Person)context.getBean("person"); 
    
   // Car car =  (Car)context.getBean("car"); 
    
  // System.out.println(car); 
  System.out.println(person); 
} 
} 

测试结果 makeing car::::123

利用FactoryBean创建car成功

只是为了说明思想。因为这个接口太重要了。在Spring中有很多类实现了该接口。

以上所述是小编给大家介绍的详解Spring中的FactoryBean,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持!

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