从头认识Spring-2.6 在注解中使用表达式@Value-使用表达式注入其他对象的值

Posted 2020-06-14 李灵晖

这一章节我们来讨论一下在注解中使用表达式@Value，使用表达式注入其他对象的值。

1.domain

蛋糕类：只有一个public的名称

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_18;

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

public class Cake {

	@Value("blueberry cheese cake")
	public String name = "";

}

上面需要注意的是我们通过@Value注入蛋糕名称

烤炉类：只有一个public的名称

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_18;

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

public class Oven {
	@Value("bigOven")
	public String name = "";
}

上面需要注意的是我们通过@Value注入烤炉名称

厨师类：

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_18;

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

public class Chief {

	@Value("jack")
	private String name = "";

	@Value("#{cake.name}")
	private String cakeName = "";

	@Value("#{oven.name}")
	private String ovenName = "";

	public void makeOneCake() {
		System.out.println(name + " use " + ovenName + " to make " + cakeName);
	}
}

上面需要注意的是我们通过@Value，然后在里面加入表达式，注入厨师的名称、蛋糕的名称和烤炉的名称

表达式的应用跟SpEl在xml里面的使用一样，可以查看之前的文章。

2.测试类：

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_18;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {
		"/com/raylee/my_new_spring/my_new_spring/ch02/topic_1_18/ApplicationContext-test.xml" })
public class ChiefTest {

	@Autowired
	private ApplicationContext applicationContext;

	@Test
	public void testChief() {
		Chief jack = applicationContext.getBean(Chief.class);
		jack.makeOneCake();
	}
}

3.配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:aop="http://www.springframework.org/schema/aop" xmlns:util="http://www.springframework.org/schema/util"
	xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd
		http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.0.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
	<bean id="cake"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_18.Cake" />
	<bean id="oven"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_18.Oven" />
	<bean id="jack"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_18.Chief" />
</beans>

所有的bean只需要配置id

测试输出：

jack use bigOven to make blueberry cheese cake

总结：这一章节主要介绍了使用表达式注入其他对象的值。

目录：http://blog.csdn.net/raylee2007/article/details/50611627 

 

我的github：https://github.com/raylee2015/my_new_spring