spring学习（官网）——使用工厂方法实例化对象

1：使用静态工厂方法实例化bean：在spring配置文件中注册bean，class属性是包含静态的类，

factory-method

指定类对应的工厂方法名

<bean id="clientService"
class="examples.ClientService"
factory-method="createInstance"/>

public class ClientService {
private static ClientService clientService = new ClientService();
private ClientService() {}

public static ClientService createInstance() {
return clientService;
}
}

2：使用工厂方法是实例实例化对象：
<!-- the factory bean, which contains a method called createInstance() -->
<bean id="serviceLocator" class="examples.DefaultServiceLocator">
<!-- inject any dependencies required by this locator bean -->
</bean>

<!-- the bean to be created via the factory bean -->
<bean id="clientService"
factory-bean="serviceLocator"
factory-method="createClientServiceInstance"/>

public class DefaultServiceLocator {

private static ClientService clientService = new ClientServiceImpl();
private DefaultServiceLocator() {}

public ClientService createClientServiceInstance() {
return clientService;
}
}

<bean id="serviceLocator" class="examples.DefaultServiceLocator">
<!-- inject any dependencies required by this locator bean -->
</bean>

<bean id="clientService"
factory-bean="serviceLocator"
factory-method="createClientServiceInstance"/>

<bean id="accountService"
factory-bean="serviceLocator"
factory-method="createAccountServiceInstance"/>

public class DefaultServiceLocator {

private static ClientService clientService = new ClientServiceImpl();
private static AccountService accountService = new AccountServiceImpl();

private DefaultServiceLocator() {}

public ClientService createClientServiceInstance() {
return clientService;
}

public AccountService createAccountServiceInstance() {
return accountService;
}

}