版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/zxd1435513775/article/details/83033622
一、引言
对于通过类名在配置文件中配置Bean是再普通不过的配置了,此处略过,主要介绍通过静态工厂方法和实例工厂方法从容器中获取Bean,下面直接上代码。
二、静态工厂方法
1、实体类
public class Car {
private String brand;
private String price;
public Car(String brand, String price) {
super();
this.brand = brand;
this.price = price;
}
public String getBrand() {
return brand;
}
public void setBrand(String brand) {
this.brand = brand;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
@Override
public String toString() {
return "Car [brand=" + brand + ", price=" + price + "]";
}
}
2、静态工厂类
public class StaticCarFactory {
private static Map<String, Car> cars = new HashMap<>();
static {
cars.put("audi", new Car("audi", "300000"));
cars.put("bens", new Car("bens", "400000"));
}
public static Car getCar(String name) {
return cars.get(name);
}
}
3、application.xml配置文件:
<bean id="car1" class="com.scorpios.spring.factory.StaticCarFactory" factory-method="getCar">
<constructor-arg value="bens"></constructor-arg>
</bean>
属性解释:
class属性:指向静态工厂方法的全类名;
factory-method: 指向静态工厂方法的名字;
constructor-arg: 如果工厂方法需要传入参数,则使用constructor-arg来配置参数;
注意:通过静态工厂方法来配置bean,注意不是配置静态工厂方法实例,而是配置bean实例
4、测试类:
public class Main {
public static void main(String[] args) {
ApplicationContext apx = new ClassPathXmlApplicationContext("bean-factory.xml");
Car car1 = (Car) apx.getBean("car1");
System.out.println(car1);
}
}
5、测试结果:
二、实例工厂方法
1、实体类同上:
2、实例工厂类:
public class InstanceCarFactory {
private Map<String, Car> cars = null;
public InstanceCarFactory() {
cars = new HashMap<>();
cars.put("BMW", new Car("BMW", "500000"));
cars.put("Audi", new Car("Audi", "300000"));
}
public Car getCar(String name) {
return cars.get(name);
}
}
3、application.xml配置文件:
<!-- 配置工厂方法 -->
<bean id="carFactory" class="com.xudong.spring.factory.InstanceCarFactory"></bean>
<!-- 通过实例工厂方法来配置bean -->
<bean id="car2" factory-bean="carFactory" factory-method="getCar">
<constructor-arg value="BMW"></constructor-arg>
</bean>
属性解释:
factory-bean 属性:指向实例工厂方法的bean
factory-method: 指向静态工厂方法的名字;
constructor-arg:如果工厂方法需要传入参数,则使用constructor-arg来配置参数;
注意:即先需要创建工厂本身,再调用工厂的实例方法来返回bean的实例
4、测试类:
public class Main {
public static void main(String[] args) {
ApplicationContext apx = new ClassPathXmlApplicationContext("bean-factory.xml");
Car car2 = (Car) apx.getBean("car2");
System.out.println(car2);
}
}