Spring学习（14）--- 基于Java类的配置Bean 之 @ImportResource & @Value 注解

时间：2022-08-10 22:42:14

学习如何使用@ImportResource 和 @Value 注解进行资源文件读取

例子：

先创建一个MyDriverManager类（模拟读取数据库配置信息）

package com.beanannotation;

public class MyDriverManager {

	public MyDriverManager(String url,String username,String password){

		System.out.println("url : "+url);

		System.out.println("username : "+username);

		System.out.println("password : "+password);

	}

}

创建StoreConfig

package com.beanannotation;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.context.annotation.ImportResource;

@Configuration

@ImportResource("classpath:config.xml")

public class StoreConfig {

	@Value("${url}")

	private String url;

	@Value("${username}")

	private String username;

	@Value("${password}")

	private String password;

	@Bean

	public MyDriverManager myDriverManager(){

		return new MyDriverManager(url,username,password);

	}

}

XML配置（context:property-placeholder 指定资源文件的位置）

<?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-4.1.xsd

            http://www.springframework.org/schema/context

            http://www.springframework.org/schema/context/spring-context-4.1.xsd">

     <context:property-placeholder location="classpath:config.properties"/> 

     <context:component-scan base-package="com.beanannotation">

     </context:component-scan>

</beans>

创建资源文件config.properties

url=127.0.0.1

username=root

password=123456

单元测试：

package com.beanannotation;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class UnitTest {

	@Test

	public void test(){

		ApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring-beanannotation.xml");

		MyDriverManager service=(MyDriverManager)context.getBean("myDriverManager");

		System.out.println(service.getClass().getName());

	}

}

结果：

2015-7-7 17:22:25 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@36b8bef7: startup date [Tue Jul 07 17:22:25 CST 2015]; root of context hierarchy

2015-7-7 17:22:25 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [config.xml]

2015-7-7 17:22:25 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [config.xml]

2015-7-7 17:22:25 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties

信息: Loading properties file from class path resource [config.properties]

2015-7-7 17:22:25 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties

信息: Loading properties file from class path resource [config.properties]

url : 127.0.0.1

username : Administrator

password : 123456

com.beanannotation.MyDriverManager

PS：有没有发现结果有异常----username 不是root 而是计算机的当前用户名

@Value("${username}") 在取值的时候，会去取当前用户的名称

所以在以后的使用中，要避免使用username

所以，修改一下config.properties 和StoreConfig

jdbc.url=127.0.0.1

jdbc.username=root

jdbc.password=123456

package com.beanannotation;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.context.annotation.ImportResource;

@Configuration

@ImportResource("classpath:config.xml")

public class StoreConfig {

	@Value("${jdbc.url}")

	private String url;

	@Value("${jdbc.username}")

	private String username;

	@Value("${jdbc.password}")

	private String password;

	@Bean

	public MyDriverManager myDriverManager(){

		return new MyDriverManager(url,username,password);

	}

}

测试同上：

结果：

2015-7-7 17:26:41 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh

信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@32bf7190: startup date [Tue Jul 07 17:26:41 CST 2015]; root of context hierarchy

2015-7-7 17:26:41 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [config.xml]

2015-7-7 17:26:41 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

信息: Loading XML bean definitions from class path resource [config.xml]

2015-7-7 17:26:41 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties

信息: Loading properties file from class path resource [config.properties]

2015-7-7 17:26:41 org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties

信息: Loading properties file from class path resource [config.properties]

url : 127.0.0.1

username : root

password : 123456

com.beanannotation.MyDriverManager

这下就可以了

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