Guice：Binder#bindConstant() 和 Binder#bind() 之间的区别 ... toInstance
我想问一下有什么区别
bindConstant().annotatedWith(Names.named("keepAliveInterval")).to(60);
，
bind(Integer.TYPE).annotatedWith(Names.named("keepAliveInterval")).toInstance(60);
我想用 Names.bindProperties(binder(), prop); 加载所有配置属性；在我的模块中，我发现它使用后一个来绑定属性。
谢谢，问候
马雷克
I would like to ask what's the difference between
bindConstant().annotatedWith(Names.named("keepAliveInterval")).to(60);
and
bind(Integer.TYPE).annotatedWith(Names.named("keepAliveInterval")).toInstance(60);
I would like to load all my configuration properties with Names.bindProperties(binder(), prop); in my module and I discovered that it uses the latter one for binding properties.
Thanks, regards
Marek
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我认为使用
bindConstant()的原因是：bindConstant().to(foo)。由于您绑定的类型是基元和 String，因此无注释绑定对它们中的任何一个都不太有意义。bindConstant()将int绑定到Integer.class而不是Integer.TYPE，不确定这是否重要）。我认为
Names.bindProperties不使用bindConstant只是因为它是内部代码，并且在进行绑定的过程中跳过一两个步骤就可以多一点代码。在您自己的模块中，我只使用bindConstant因为它简单且更清晰。I think reasons to use
bindConstant()are:bindConstant().to(foo). Since the types you bind with it are primitives andStrings, it's unlikely that an annotation-less binding would make sense for any of them.bindConstant()binds aninttoInteger.classrather thanInteger.TYPE, not sure if that matters).I think
Names.bindPropertiesdoesn't usebindConstantjust because it's internal code and a little more code is OK to skip a step or two in the process of making a binding. In your own modules, I'd just usebindConstantbecause it's easy and more clear.bindConstant()的好处是能够设置不同的原语，因为 Guice 本身预定义了TypeConverter实例。以下面的绑定定义为例：
bindContant().annotatedWith(@Names.named("c")).to("30");然后在你想要注入的类中：
@Inject @Named("c") int value;Guice 会将绑定的
String转换为int。如果不能的话，它会这样说。bindConstant()的好处是可以发生类型转换。显式绑定int并不会给您带来那种奢侈。bindConstant()has the benefit of being able to set different primitives because of predefinedTypeConverterinstances within Guice itself.Take the following binding definition as an example:
bindContant().annotatedWith(@Names.named("c")).to("30");Then in a class where you want the injection:
@Inject @Named("c") int value;Guice will convert the bound
Stringinto anintfor you. If it cannot, it will say so.The benefit of
bindConstant()is the type conversion that can happen. Explicitly binding anintdoes not give you that luxury.