Spring的執行個體工廠方法和靜态工廠方法

 靜态工廠方法：直接調用靜态方法可以傳回Bean的執行個體 package com.zhu.string.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(3000, "aodi"));

cars.put("fodo", new Car(3000, "aodi"));

}

//靜态工廠方法

public static Car getCar(String name){

return cars.get(name);

}

} 執行個體工廠方法。即調用工廠本身，再調用工廠的執行個體方法來傳回bean執行個體 package com.zhu.string.factory;

import java.util.HashMap;

import java.util.Map;

public class InstanceCarFactory {

private Map<String ,Car> cars=null;

public InstanceCarFactory() {

// TODO Auto-generated constructor stub

cars=new HashMap<String, Car>();

cars.put("audi", new Car(1000,"audi"));

cars.put("dffdas", new Car(2000,"audi"));

}

public Car getCar(String brand){

return cars.get(brand);

}

}

beans-factory.xml <?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 

xmlns:p="http://www.springframework.org/schema/p"

xsi:schemaLocation="http://www.springframework.org/schema/beans 

http://www.springframework.org/schema/beans/spring-beans.xsd">

<!-- 通過靜态方法來配置bean,注意不是配置靜态工廠方法執行個體，而是配置bean執行個體 

-->

<!--

class屬性：指向靜态方法的全類名 factory-method：指向靜态方法的名字

constructor-arg:如果工廠方法需要傳入參數，則使用constructor-arg來配置參數

-->

<bean id="car1" factory-method="getCar"

class="com.zhu.string.factory.StaticCarFactory">

<constructor-arg value="audi"></constructor-arg>

</bean>

<!-- 配置工廠的執行個體 -->

<bean id="carFactory" class="com.zhu.string.factory.InstanceCarFactory">

</bean>

<bean id="car2" factory-bean="carFactory" factory-method="getCar">

<constructor-arg value="audi"></constructor-arg>

</bean>

</beans>

Car.java實體類 package com.zhu.string.factory;

public class Car {

private double price;

private String brand;

public double getPrice() {

return price;

}

public void setPrice(double price) {

this.price = price;

}

public String getBrand() {

return brand;

}

public void setBrand(String brand) {

this.brand = brand;

}

@Override

public String toString() {

return "Car [brand=" + brand + ", price=" + price + "]";

}

public Car(){

System.out.println("cars....constructor");

}

public Car(double price, String brand) {

super();

this.price = price;

this.brand = brand;

}

}

Main.java package com.zhu.string.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  cx=new ClassPathXmlApplicationContext("beans-factory.xml");

Car car1=(Car) cx.getBean("car1");

System.out.println(car1);

Car car2=(Car) cx.getBean("car2");

System.out.println(car2);

}

}

運作結果：

Car [brand=aodi, price=3000.0]

Car [brand=audi, price=1000.0]