Java Guice@提供了带有可选可空注入的函数,但该函数不起作用
代码优先:Java Guice@提供了带有可选可空注入的函数,但该函数不起作用,java,inversion-of-control,guice,Java,Inversion Of Control,Guice,代码优先: @Slf4j public class HelperModule extends AbstractModule { @Override protected void configure() { } @Provides @Named("plugin") @Singleton public Reflections getReflections(@Nullable @Named("plugin-scope") String
@Slf4j
public class HelperModule extends AbstractModule
{
@Override
protected void configure()
{
}
@Provides
@Named("plugin")
@Singleton
public Reflections getReflections(@Nullable @Named("plugin-scope") String pluginScope)
{
if (pluginScope == null)
{
pluginScope = "me.wener";
}
log.info("Create plugin scanner for '{}'", pluginScope);
return new Reflections(new ConfigurationBuilder()
.setUrls(ClasspathHelper.forPackage(pluginScope))
.addScanners(
new SubTypesScanner(),
new TypeAnnotationsScanner())
// .filterInputsBy(new FilterBuilder().include(".*\\.java").exclude(".*"))
);
}
}
我所期望的是,pluginScope
可以是空的和可选的,我按照说明进行操作,但这不起作用,我仍然得到了
No implementation for java.lang.String annotated with @com.google.inject.name.Named(value=plugin-scope) was bound
怎么了
编辑
顺便说一句,
@Nullable
是javax.annotation.Nullable
A@Nullable
注释意味着您可以绑定到返回null
的提供程序,而不是不存在绑定。您的@Nullable注释将允许以下操作:
bind(String.class).annotatedWith(Names.named("plugin-scope"))
.toProvider(Providers.<String>of(null));
bind(String.class).annotatedWith(name.named(“插件范围”))
.toProvider(提供者)(空);
您必须显式绑定到
null
的提供程序,而不是toInstance(null)
,根据。关于@Inject(optional=true)
?@MilanBaran已尝试,但仍不正确