Spring通过工厂方法配置bean

Bean 的配置方式：

基于XML的方式配置bean.

通过全类名（反射）
通过工厂方法（静态工厂方法 & 实例工厂方法）
FactoryBean 基于注解的方式配置bean.

工厂方法：

public class StaticFactory {

    private static Map<String,Person> persons = new HashMap<String,Person>();
    
    static{
        persons.put("tom", new Person("tom",12));
        persons.put("jack", new Person("jack",12));
    }
    
    //静态工厂方法。
    public static Person getPerson(String name){
        return persons.get(name);
    }
}


//实例工厂，需要创建工厂本身，再调用工厂的实例(对象)方法来返回需要的对象本身。
public class InstanceFactory {

    private Map<String,Person> persons = null;
    
    public InstanceFactory(){
        persons = new HashMap<String,Person>();
        persons.put("haha", new Person("haha",18));
        persons.put("xixi", new Person("xixi",18));
    }
    
    public Person getPerson(String name){
        return persons.get(name);
    }
}

通过静态工厂方法配置bean

<bean id="tom" 
    class="com.chai.lesson1.StaticFactory"
    factory-method="getPerson">
        <constructor-arg value="tom"></constructor-arg>
    </bean>

通过实例工厂方法配置bean

<!-- 配置工厂本身-->
    <bean id="instanceFactory" class="com.chai.lesson1.InstanceFactory">
    </bean>
    <!-- 配置需要的bean实例 factory-bean指向实例工厂的bean，  factory-method实例工厂的方法名。-->
    <bean id="xixi" factory-bean="instanceFactory" factory-method="getPerson">
        <constructor-arg value="xixi"></constructor-arg>
    </bean>

FactoryBean:通过factorybean 配置 bean的实例。property配置factorybean的属性值
XML文件：

<bean id="p1" class="com.chai.lesson1.PersonFactoryBean">
        <property name="name" value="beanfactory..."></property>
    </bean>

FactoryBean实现类：

public class PersonFactoryBean implements FactoryBean<Person> {

    private String name;

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public Person getObject() throws Exception {
        // TODO Auto-generated method stub
        return new Person(name,30);
    }

    @Override
    public Class<?> getObjectType() {
        // TODO Auto-generated method stub
        return Person.class;
    }


    @Override
    public boolean isSingleton() {
        // TODO Auto-generated method stub
        return true;
    }
}