java 处理一个 Spring bean/接口的多个实现
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Handling several implementations of one Spring bean/interface
提问by balteo
Say I need to rely on several implementationsof a Spring bean. I have one AccountServiceinterface and two implementations: DefaultAccountServiceImpland SpecializedAccountServiceImpl.
假设我需要依赖Spring bean 的几种实现。我有一个AccountService接口和两个实现：DefaultAccountServiceImpl和SpecializedAccountServiceImpl.
How is this possible (injecting one or the other implementation) in Spring?
Which implementation will the following injection use?
@Autowired private AccountService accountService;
这在 Spring 中怎么可能（注入一个或另一个实现）？
以下注入将使用哪种实现？
@Autowired private AccountService accountService;
回答by Tomasz Nurkiewicz
Ad. 1: you can use @Qualifierannotationor autowire using @Resourceas opposed to @Autowiredwhich defaults to field name rather than type.
广告。1：可以使用@Qualifier注释使用或自动装配@Resource，而不是@Autowired默认为字段名称，而不是类型。
Ad. 2: It will fail at runtime saying that two beans are implementing this interface. If one of your beans is additionally annotated with @Primary, it will be preferred when autowiring by type.
广告。2：它会在运行时失败，说两个 bean 正在实现这个接口。如果您的一个 bean 还附加了注释@Primary，则在按类型自动装配时将首选它。
回答by Rajeev Singla
@Autowired
@Qualifier("impl1")
BaseInterface impl1;
@Autowired
@Qualifier("impl2")
BaseInterface impl2;
@Component(value="impl1")
public class Implementation1 implements BaseInterface {
}
@Component(value = "impl2")
public class Implementation2 implements BaseInterface {
}
For full code: https://github.com/rsingla/springautowire/
