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Spring入门第十二课
Bean的配置方法
通过工厂方法(静态工厂方法&实例工厂方法),FactoryBean
通过调用静态工厂方法创建Bean
调用静态工厂方法创建Bean是将对象创建的过程封装到静态方法中,当客户端需要对象时,只需要简单的调用静态方法,而不用关心创建对象的细节。
要声明通过静态方法创建的Bean,需要在Bean的class属性里指定拥有该工厂的方法类,同时在factory-method属性里指定工厂方法的名称,最后,使用<constructor-arg>元素为该方法传递方法参数。
看代码
package logan.spring.study.factory; public class Car { private String brand; private int price; public String getBrand() { return brand; } public void setBrand(String brand) { this.brand = brand; } public int getPrice() { return price; } public void setPrice(int price) { this.price = price; } @Override public String toString() { return "Car [brand=" + brand + ", price=" + price + "]"; } public Car(String brand, int price) { super(); this.brand = brand; this.price = price; } }
package logan.spring.study.factory; import java.util.HashMap; import java.util.Map; public class StaticCarFactory { private static Map<String, Car> cars = new HashMap<String, Car>(); static{ cars.put("audi", new Car("audi",3000000)); cars.put("ford", new Car("ford", 4000000)); } public static Car getCar(String name){ return cars.get(name); } }
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <!-- 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 --> <bean id="car1" class="logan.spring.study.factory.StaticCarFactory" factory-method="getCar"> <constructor-arg value="audi"></constructor-arg> </bean> </beans>
package logan.spring.study.factory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { // TODO Auto-generated method stub ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-factory.xml"); Car car1 = (Car) ctx.getBean("car1"); System.out.println(car1); } }
下面是输出结果:
五月 21, 2017 11:21:42 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7aec35a: startup date [Sun May 21 11:21:42 CST 2017]; root of context hierarchy
五月 21, 2017 11:21:42 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-factory.xml]
Car [brand=audi, price=3000000]
下面看实例工厂方法:
实例工厂方法就是实例工厂的方法,
package logan.spring.study.factory; import java.util.HashMap; import java.util.Map; public class InstanceCarFactory { private Map<String, Car> cars = null; public InstanceCarFactory(){ cars = new HashMap<String,Car>(); cars.put("audi", new Car("audi",300000)); cars.put("ford", new Car("ford",500000)); } public Car getCar(String brand){ return cars.get(brand); } }
下面是配置文件:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <!-- 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 --> <bean id="car1" class="logan.spring.study.factory.StaticCarFactory" factory-method="getCar"> <constructor-arg value="audi"></constructor-arg> </bean> <!-- 配置工厂的实例 --> <bean id="carFactory" class="logan.spring.study.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="ford"></constructor-arg> </bean> </beans>
package logan.spring.study.factory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { // TODO Auto-generated method stub ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-factory.xml"); Car car1 = (Car) ctx.getBean("car1"); System.out.println(car1); Car car2 = (Car) ctx.getBean("car2"); System.out.println(car2); } }
下面是输出结果
五月 21, 2017 7:27:18 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh 信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7aec35a: startup date [Sun May 21 19:27:18 CST 2017]; root of context hierarchy 五月 21, 2017 7:27:18 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions 信息: Loading XML bean definitions from class path resource [beans-factory.xml] Car [brand=audi, price=3000000] Car [brand=ford, price=500000]
Spring入门第十二课
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