Spring注解解析之@ImportResource

一、ImportResource

1.1 定义包和类

首先定义一个不会被ComponentScan扫描到的包outpackage，如下：

在该包内创建一个类：

package outpackage;

import org.springframework.stereotype.Service;

@Service
public class HelloService1 {
    public void method1() {
        System.out.println("class:HelloService1__method:method1");
    }
}

1.2 定义配置文件

在资源目录添加配置文件applicationContext.xml：

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <!-- 开启注解模式 -->
    <context:annotation-config/>

    <!-- 基于注解自动注册spring bean -->
    <context:component-scan base-package="outpackage"/>
</beans>

1.3 定义Java Config类

在启动类平级目录或者是子目录添加java config类保证能够被springboot扫描到，引入xml配置，如下：

package dongshi.daddy;

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ImportResource;

@Configuration
@ImportResource({"classpath:applicationContext.xml"})
public class OuterPackageConfiguration {
}

1.4 测试代码

@SpringBootApplication
public class HelloWorldMainApplication {

    public static void main(String[] args) throws URISyntaxException, IOException {
        ConfigurableApplicationContext run = SpringApplication.run(HelloWorldMainApplication.class, args);
        // 获取通过配置文件定义而被扫描到的类
        HelloService1 bean = run.getBean(HelloService1.class);
        System.out.println(bean);
    }
}

二、运行

2021-05-19 17:52:52.896  INFO 16232 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8083 (http) with context path ''
...snip...
outpackage.HelloService1@1929425f

为了证明确实是xml配置文件在起作用，而不是springboot自己扫描注册，修改配置类，注释掉@ImportResource({"classpath:applicationContext.xml"})，如下：

package dongshi.daddy;

import org.springframework.context.annotation.Configuration;

@Configuration
//@ImportResource({"classpath:applicationContext.xml"})
public class OuterPackageConfiguration {
}

然后运行：

2021-05-19 18:01:10.522  INFO 18260 --- [           main] dongshi.daddy.HelloWorldMainApplication  : Started HelloWorldMainApplication in 0.944 seconds (JVM running for 1.355)
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'outpackage.HelloService1' available
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:351)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:342)
 at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1123)
 at dongshi.daddy.HelloWorldMainApplication.main(HelloWorldMainApplication.java:16)

可以看到就找不到对应的bean了。

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