如何使用@Component 扫描注释扫描多个路径？

我正在使用 Spring 3.1，并使用 @Configuration和 @ComponentScan属性引导一个应用程序。

实际的开始已经完成了

new AnnotationConfigApplicationContext(MyRootConfigurationClass.class);

此 Configuration 类使用

@Configuration
@ComponentScan("com.my.package")
public class MyRootConfigurationClass

这个工作很好。不过我想更具体的包，我扫描，所以我尝试。

@Configuration
@ComponentScan("com.my.package.first,com.my.package.second")
public class MyRootConfigurationClass

但是这种方法失败了，错误告诉我它无法找到使用 @Component注释指定的组件。

我追求的正确方式是什么？

谢谢

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最佳答案

@ComponentScan uses string array, like this:

@ComponentScan({"com.my.package.first","com.my.package.second"})

When you provide multiple package names in only one string, Spring interprets this as one package name, and thus can't find it.

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Provide your package name separately, it requires a String[] for package names.

Instead of this:

@ComponentScan("com.my.package.first,com.my.package.second")

Use this:

@ComponentScan({"com.my.package.first","com.my.package.second"})
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There is another type-safe alternative to specifying a base-package location as a String. See the API here, but I've also illustrated below:

@ComponentScan(basePackageClasses = {ExampleController.class, ExampleModel.class, ExmapleView.class})

Using the basePackageClasses specifier with your class references will tell Spring to scan those packages (just like the mentioned alternatives), but this method is both type-safe and adds IDE support for future refactoring -- a huge plus in my book.

Reading from the API, Spring suggests creating a no-op marker class or interface in each package you wish to scan that serves no other purpose than to be used as a reference for/by this attribute.

IMO, I don't like the marker-classes (but then again, they are pretty much just like the package-info classes) but the type safety, IDE support, and drastically reducing the number of base packages needed to include for this scan is, with out a doubt, a far better option.

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Another way of doing this is using the basePackages field; which is a field inside ComponentScan annotation.

@ComponentScan(basePackages={"com.firstpackage","com.secondpackage"})

If you look into the ComponentScan annotation .class from the jar file you will see a basePackages field that takes in an array of Strings

public @interface ComponentScan {
String[] basePackages() default {};
}

Or you can mention the classes explicitly. Which takes in array of classes

Class<?>[]  basePackageClasses
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You use ComponentScan to scan multiple packages using

@ComponentScan({"com.my.package.first","com.my.package.second"})

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make sure you have added this dependency in your pom.xml

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
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You can also use @ComponentScans annotation:

@ComponentScans(value = { @ComponentScan("com.my.package.first"),
@ComponentScan("com.my.package.second") })
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I use:

@ComponentScan(basePackages = {"com.package1","com.package2","com.package3", "com.packagen"})

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