spring学习2之组件注册-@ComponentScan-自动扫描组件&指定扫描规则

曾经终败给现在 2022-05-13 14:54 188阅读 0赞

一，配置文件版

<table> 
 <tbody> 
  <tr> 
   <td> <pre>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;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.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"&gt;

&lt;!-- 扫包 加入此配置后，会自动扫描com。dream下面中带有@Controller，@Service，@Repository，@Component--&gt;
<span style="color:#f33b45;">    &lt;!--&lt;context:component-scan base-package="com.dream"&gt;&lt;/context:component-scan&gt;--&gt;</span>
    &lt;bean id="student" class="com.dream.bean.Student"&gt;
        &lt;property name="age" value="18"&gt;&lt;/property&gt;
        &lt;property name="name" value="lisi"&gt;&lt;/property&gt;
    &lt;/bean&gt;
&lt;/beans&gt;</pre> </td> 
  </tr> 
 </tbody> 
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在配置文件中加入<context:component-scan base-package="com.dream"></context:component-scan>，spring容器在启动的时候就会自动扫描com.dream包下面所有带@Controller，@Service，@Repository，@Component注解的类，并加载到容器。

二，注解版

1，在Config类中加入

@ComponentScan(value = "com.dream")

<table> 
 <tbody> 
  <tr> 
   <td> <pre>package com.dream.config;

import com.dream.bean.Student;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
//配置类（等价原来的配置文件）
@Configuration
@ComponentScan(value = "com.dream")
public class BeansConfig {

//给容器中注册一个bean；类型为返回值类型，id默认是方法名作为id
    @Bean
    public Student student(){
        return new Student("王五",28);
    }
}
</pre> </td> 
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2，添加下面三个类

<table> 
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  <tr> 
   <td> <pre>package com.dream.controller;

import org.springframework.stereotype.Controller;

@Controller
public class BookController {
}
</pre> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td> <pre>package com.dream.service;

import org.springframework.stereotype.Service;

@Service
public class BookService {
}
</pre> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td> <pre>package com.dream.dao;

import org.springframework.stereotype.Repository;

@Repository
public class BookDao {
}
</pre> </td> 
  </tr> 
 </tbody> 
</table>

3，在pom文件加入junit依赖

<table> 
 <tbody> 
  <tr> 
   <td> <pre>&lt;dependency&gt;
    &lt;groupId&gt;junit&lt;/groupId&gt;
    &lt;artifactId&gt;junit&lt;/artifactId&gt;
    &lt;version&gt;4.12&lt;/version&gt;
    &lt;scope&gt;test&lt;/scope&gt;
&lt;/dependency&gt;</pre> </td> 
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</table>

4，测试类

<table> 
 <tbody> 
  <tr> 
   <td> <pre>package com.dream;

import com.dream.config.BeansConfig;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class IOCTest {

@Test
    public void test1(){
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(BeansConfig.class);
        String[] beanDefinitionNames = applicationContext.getBeanDefinitionNames();

for(String bean:beanDefinitionNames){
            System.out.println(bean);
        }
    }
}
</pre> </td> 
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5，测试结果  红色字段代表我们自己注入容器的类，绿色部分是spring启动时，spring中需要注入的部分

<table> 
 <tbody> 
  <tr> 
   <td><span style="color:#86ca5e;">org.springframework.context.annotation.internalConfigurationAnnotationProcessor<br> org.springframework.context.annotation.internalAutowiredAnnotationProcessor<br> org.springframework.context.annotation.internalRequiredAnnotationProcessor<br> org.springframework.context.annotation.internalCommonAnnotationProcessor<br> org.springframework.context.event.internalEventListenerProcessor<br> org.springframework.context.event.internalEventListenerFactory</span><br><span style="color:#f33b45;">beansConfig<br> bookController<br> bookDao<br> bookService<br> student</span></td> 
  </tr> 
 </tbody> 
</table>

6，测试  excludeFilters，配置类如下

<table> 
 <tbody> 
  <tr> 
   <td> <pre>package com.dream.config;

import com.dream.bean.Student;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Service;

//配置类（等价原来的配置文件）
@Configuration
<span style="color:#f33b45;">@ComponentScan(value = "com.dream",excludeFilters = {
        @ComponentScan.Filter(type=FilterType.ANNOTATION,classes={Controller.class, Service.class})//排除Controller和Service以外的其他需要注入的类</span>
})
public class BeansConfig {

结果中没有带@Controller和@Service的类

<table> 
 <tbody> 
  <tr> 
   <td>org.springframework.context.annotation.internalConfigurationAnnotationProcessor<br> org.springframework.context.annotation.internalAutowiredAnnotationProcessor<br> org.springframework.context.annotation.internalRequiredAnnotationProcessor<br> org.springframework.context.annotation.internalCommonAnnotationProcessor<br> org.springframework.context.event.internalEventListenerProcessor<br> org.springframework.context.event.internalEventListenerFactory<br> beansConfig<br> bookDao<br> student</td> 
  </tr> 
 </tbody> 
</table>

7，测试  includeFilters，配置如下，使用includeFilters ，需要将useDefaultFilters 设置为false才生效

<table> 
 <tbody> 
  <tr> 
   <td> <pre>package com.dream.config;

import com.dream.bean.Student;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Service;

//配置类（等价原来的配置文件）
@Configuration
@ComponentScan(value = "com.dream",includeFilters = {
        @ComponentScan.Filter(type=FilterType.ANNOTATION,classes={Controller.class, Service.class})//排除Controller和Service以外的其他需要注入的类
},<span style="color:#f33b45;">useDefaultFilters = false)</span>
public class BeansConfig {

测试结果