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<car>{ 
   
  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：

<bean id="car" class="com.myapp.core.factorybean.mycarfactorybean"> 
  <property name="make" value="makeing car"/> 
  <property name="year" value="123"/> 
</bean> 
 
<bean id="person" class="com.myapp.core.factorybean.person"> 
 
<property name="car" ref="car"/> 
 
</bean> 

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