Spring入门第十四课

Posted 2020-09-19 alittlecomputer

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基于注解的方式配置bean（基于注解配置Bean，基于注解来装配Bean的属性）

在classpath中扫描组件

组件扫描（component scanning）：Spring能够从classpath下自动扫描，侦测和实例化具有特定注解的组件。

特定组件包括：

-@Component：基本注解，表示了一个受Spring管理的组件

-@Respository:标识持久层组件

-@Service：标识服务层组（业务层）件

-@Controller:标识表现层组件

对于扫描到的组件，Spring有默认的命名策略：使用非限定类名，第一个字母小写，也可以在注解中通过value属性值标识组件的名称。

当在组件类上使用了特定的注解之后，还需要在Spring的配置文件中声明<context:component-scan>:

-base-package属性指定一个需要扫描的基类包，Spring容器将会扫描这个基类包里面及其子包中的所有类。

-当需要扫描多个包时，可以使用逗号分隔。

-如果仅希望扫描特定的类而不非基包下的所有类，可以使用resource-pattern属性过滤特定的类，示例：

<context:component-scan
    base-package="com.logan.spring.beans"
    resource-pattern="autowire/*.class"/>

-<context:include-filter>子节点表示要包含的目标类

-<context:exclude-filter>子节点表示要排除在外的目标

-<context:component-scan>下可以拥有若干个<context:include-filter>和<context:exclude-filter>子节点。

看代码

package logan.spring.study.annotation;

import org.springframework.stereotype.Component;

@Component
public class TestObject {

}

package logan.spring.study.annotation.repository;

import org.springframework.stereotype.Repository;

@Repository("userRepository")
public class UserRepositoryImpl implements UserRepository {

    @Override
    public void save() {
        // TODO Auto-generated method stub
        System.out.println("UserRepository Save...");

    }

}

package logan.spring.study.annotation.service;

import org.springframework.stereotype.Service;

@Service
public class UserService {
    
    public void add(){
        System.out.println("UserService add...");
    }
}

package logan.spring.study.annotation.controller;

import org.springframework.stereotype.Controller;

@Controller
public class UserController {
    
    public void execute(){
        System.out.println("UserController execute...");
    }

}

配置文件

<?xml version="1.0" encoding="UTF-8"?>
<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-4.3.xsd">
    
    <context:component-scan base-package="logan.spring.study.annotation"></context:component-scan>

</beans>

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;
import logan.spring.study.annotation.repository.UserRepository;
import logan.spring.study.annotation.service.UserService;

public class Main {
    public static void main(String[] args) {
        System.out.println(1);
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");
        System.out.println(2);
        TestObject to = (TestObject) ctx.getBean("testObject");
        System.out.println(to);
        
        UserController userController = (UserController) ctx.getBean("userController");
        System.out.println(userController);
        
        UserService userService = (UserService) ctx.getBean("userService");
        System.out.println(userService);
        
        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");
        System.out.println(userRepository);
    }

}

package logan.spring.study.annotation.repository;

public interface UserRepository {
    
    void save();

}

返回的结果为

五月 24, 2017 10:25:12 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Wed May 24 22:25:11 CST 2017]; root of context hierarchy
五月 24, 2017 10:25:12 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-annotation.xml]
logan.spring.study.annotation.TestObject@78ac1102
logan.spring.study.annotation.controller.UserController@2de8284b
logan.spring.study.annotation.service.UserService@396e2f39
logan.spring.study.annotation.repository.UserRepositoryImpl@a74868d

这里使用的jar包有：

可以如下改规则：（通过resource-pattern指定扫描资源）

<?xml version="1.0" encoding="UTF-8"?>
<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-4.3.xsd">
    
    <context:component-scan 
    base-package="logan.spring.study.annotation" 
    resource-pattern="repository/*.class" ></context:component-scan>

</beans>

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;
import logan.spring.study.annotation.repository.UserRepository;
import logan.spring.study.annotation.service.UserService;

public class Main {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");
//        TestObject to = (TestObject) ctx.getBean("testObject");
//        System.out.println(to);
        
//        UserController userController = (UserController) ctx.getBean("userController");
//        System.out.println(userController);
        
//        UserService userService = (UserService) ctx.getBean("userService");
//        System.out.println(userService);
        
        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");
        System.out.println(userRepository);
    }

}

输出的结果为：

五月 24, 2017 10:30:25 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Wed May 24 22:30:25 CST 2017]; root of context hierarchy
五月 24, 2017 10:30:25 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-annotation.xml]
logan.spring.study.annotation.repository.UserRepositoryImpl@32eebfca

<context:include-filter>和<context:exclude-filter>子节点支持多种类型的过滤表达式：

类别	示例	说明
annotation	com.logan.XxxAnnotation	所有标注了XxxAnnotation的类，该类型采用目标类是否标注了某个注解进行过滤
assinable	com.logan.XxxService	所有继承或扩展XxxService的类，该类型采用目标类是否基层或扩展某个特定类型进行过滤
aspecct	com.logan.*Service+	所有类名以Service结束的类以及继承或者扩展它们的类，该类型采用AspectJ表达式进行过滤。
regex	com.logan.\\anno\\.*	所有com.logan.anno包下的类，该类型采用正则表达式根据类的类名进行过滤
custom		采用XxxTypeFilter,通过代码的方式定义过滤规则，该类必须实现org.springframework.core.type.TypeFilter接口。

看如下配置：

<?xml version="1.0" encoding="UTF-8"?>
<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-4.3.xsd">
    
    <context:component-scan 
    base-package="logan.spring.study.annotation">
    <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"></context:exclude-filter></context:component-scan>

</beans>

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;
import logan.spring.study.annotation.repository.UserRepository;
import logan.spring.study.annotation.service.UserService;

public class Main {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");
        TestObject to = (TestObject) ctx.getBean("testObject");
        System.out.println(to);
        
        UserController userController = (UserController) ctx.getBean("userController");
        System.out.println(userController);
        
        UserService userService = (UserService) ctx.getBean("userService");
        System.out.println(userService);
        
//        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");
//        System.out.println(userRepository);
    }

}

下面是输出结果

五月 25, 2017 10:21:53 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Thu May 25 22:21:53 CST 2017]; root of context hierarchy
五月 25, 2017 10:21:53 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-annotation.xml]
logan.spring.study.annotation.TestObject@75881071
logan.spring.study.annotation.controller.UserController@2a70a3d8
logan.spring.study.annotation.service.UserService@289d1c02

看如下代码：

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;
import logan.spring.study.annotation.repository.UserRepository;
import logan.spring.study.annotation.service.UserService;

public class Main {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");
//        TestObject to = (TestObject) ctx.getBean("testObject");
//        System.out.println(to);
//        
//        UserController userController = (UserController) ctx.getBean("userController");
//        System.out.println(userController);
//        
//        UserService userService = (UserService) ctx.getBean("userService");
//        System.out.println(userService);
        
        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");
        System.out.println(userRepository);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<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-4.3.xsd">
    
    <context:component-scan 
    base-package="logan.spring.study.annotation" use-default-filters="false">
    <context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"></context:include-filter></context:component-scan>

</beans>

输出结果

五月 26, 2017 9:37:08 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Fri May 26 21:37:08 CST 2017]; root of context hierarchy
五月 26, 2017 9:37:08 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-annotation.xml]
logan.spring.study.annotation.repository.UserRepositoryImpl@78ac1102

<context:include-filter>子节点包含哪些表达式的组件，该子节点需要use-default-filter配合使用。

看如下配置：（指定不包括谁）

<?xml version="1.0" encoding="UTF-8"?>
<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-4.3.xsd">
    
    <context:component-scan 
    base-package="logan.spring.study.annotation">
    <context:exclude-filter type="assignable" expression="logan.spring.study.annotation.repository.UserRepository"></context:exclude-filter>
    </context:component-scan>

</beans>

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;
import logan.spring.study.annotation.repository.UserRepository;
import logan.spring.study.annotation.service.UserService;

public class Main {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");
        TestObject to = (TestObject) ctx.getBean("testObject");
        System.out.println(to);
        
        UserController userController = (UserController) ctx.getBean("userController");
        System.out.println(userController);
        
        UserService userService = (UserService) ctx.getBean("userService");
        System.out.println(userService);
        
        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");
        System.out.println(userRepository);
    }
}

输出结果：

五月 27, 2017 11:04:35 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 11:04:35 CST 2017]; root of context hierarchy
五月 27, 2017 11:04:36 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-annotation.xml]
logan.spring.study.annotation.TestObject@289d1c02
logan.spring.study.annotation.controller.UserController@22eeefeb
logan.spring.study.annotation.service.UserService@17d0685f
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named \'userRepository\' available
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:687)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1207)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081)
    at logan.spring.study.annotation.Main.main(Main.java:22)

看下面配置：（指定包含谁）

<?xml version="1.0" encoding="UTF-8"?>
<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-4.3.xsd">
    
    <context:component-scan 
    base-package="logan.spring.study.annotation" use-default-filters="false">
    <context:include-filter type="assignable" expression="logan.spring.study.annotation.repository.UserRepository"></context:include-filter>
    </context:component-scan>

</beans>

package logan.spring.study.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import logan.spring.study.annotation.controller.UserController;
import logan.spring.study.annotation.repository.UserRepository;
import logan.spring.study.annotation.service.UserService;

public class Main {
    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-annotation.xml");
//        TestObject to = (TestObject) ctx.getBean("testObject");
//        System.out.println(to);
//        
//        UserController userController = (UserController) ctx.getBean("userController");
//        System.out.println(userController);
//        
//        UserService userService = (UserService) ctx.getBean("userService");
//        System.out.println(userService);
        
        UserRepository userRepository = (UserRepository) ctx.getBean("userRepository");
        System.out.println(userRepository);
    }
}

输出结果：

五月 27, 2017 11:07:17 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@42110406: startup date [Sat May 27 11:07:17 CST 2017]; root of context hierarchy
五月 27, 2017 11:07:17 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [beans-annotation.xml]
logan.spring.study.annotation.repository.UserRepositoryImpl@13eb8acf

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