設(shè)計(jì)模式

工廠模式生成bean

工廠模式分為靜態(tài)工廠和實(shí)例工廠

靜態(tài)工廠：

#靜態(tài)工廠通過(guò)靜態(tài)方法獲取實(shí)例，實(shí)例為靜態(tài)方法和類初始化一起

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

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

    // 靜態(tài)方法
    public static ClientService createInstance() {
        return clientService;
    }
}

實(shí)例工廠

# 實(shí)例工廠有專門(mén)的工廠類，根據(jù)不同工廠方法獲取不同的實(shí)例類型
# DefaultServiceLocator 為實(shí)例工廠類
<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();

    public ClientService createClientServiceInstance() {
        return clientService;
    }

    public AccountService createAccountServiceInstance() {
        return accountService;
    }
}