Java 使用 Spring 和注解 @Value 注入属性
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Injecting Properties using Spring & annotation @Value
提问by haju
I am trying to load a properties file into a Spring bean and then inject that bean into a class.
我正在尝试将属性文件加载到 Spring bean 中，然后将该 bean 注入到一个类中。
The only part I can't get to work seems to be using the @Resourcereference.Can someone connect the last piece for me? I get a null value every time. Doesn't seem to want to inject the value.
我无法开始工作的唯一部分似乎是使用@Resource引用。有人可以为我连接最后一部分吗？我每次都得到一个空值。似乎不想注入值。
[EDIT] - I originally thought using the @Resourcewas the best way but the proposed solution I found easier.
[编辑] - 我最初认为使用@Resource是最好的方法，但我发现建议的解决方案更容易。
I saw this solution in another post:
我在另一篇文章中看到了这个解决方案：
Reference Solution Link:Inject Property Value into Spring - posted by DON
参考解决方案链接：将属性值注入 Spring - 由 DON 发布
Credit to Don for the post but I just wasn't sure how to finish it with the @Resource.
感谢 Don 的帖子，但我不确定如何用@Resource完成它。
Debugging Results:The variable value appPropertiesis always null. It's not being injected.
调试结果：变量值appProperties始终为空。不是注射。
Spring Config.
弹簧配置。
Sample Class:
示例类：
package test;
import java.util.Properties;
import javax.annotation.Resource;
public class foo {
public foo() {}
@Resource private java.util.Properties appProperties;
}
Based on the advice in the approved solution below. Here are the changes I made.
基于以下已批准解决方案中的建议。这是我所做的更改。
Solution Update:
解决方案更新：
Spring Config:
弹簧配置：
Java Class:
Java类：
采纳答案by abalogh
For your solution to work you would also need to make foo a Spring managed bean; because otherwise how would Spring know that it has to deal with any of your annotations on your class?
为了使您的解决方案起作用，您还需要使 foo 成为 Spring 管理的 bean；因为否则 Spring 怎么会知道它必须处理您类上的任何注释？
- You can either specify it in your appcontext xml as a bean with
..class="foo" - Or use
component-scanand specify a base package which contains yourfooclass.
- 您可以在 appcontext xml 中将其指定为 bean
..class="foo" - 或者使用
component-scan并指定包含您的foo类的基本包。
Since I'm not entirely sure this is exactly what you want (don't you want a .properties fileto be parsed by Spring and have it's key-value pairs available instead of a Propertiesobject?), I'm suggesting you another solution: Using the utilnamespace
由于我不完全确定这正是您想要的（您不希望Spring 解析.properties文件并使用它的键值对而不是Properties对象吗？），我建议您使用另一种解决方案: 使用util命名空间
<util:properties id="props" location="classpath:com/foo/bar/props.properties"/>
And reference the values inside your beans (also, have to be Spring managed):
并引用 bean 中的值（也必须由 Spring 管理）：
@Value("#{props.foo}")
public void setFoo(String foo) {
this.foo = foo;
}
EDIT:
编辑：
just realized that you are importing org.springframework.context.ApplicationContextin your class which is probably unnecessary. I strongly encourage you to read Spring referenceat least the first few chapters, because a) it's a great read b) you will find it much easier to understand Spring if the basics are clear.
刚刚意识到你正在org.springframework.context.ApplicationContext你的班级中导入这可能是不必要的。我强烈建议您至少阅读前几章的Spring 参考，因为 a) 这是一本很好的读物 b) 如果基础知识清晰，您会发现理解 Spring 会容易得多。
回答by alexey28
Just one more solution using properties placeholder.
使用属性占位符的另一种解决方案。
The spring context:
春天的背景：
<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-3.1.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.1.xsd">
<context:component-scan base-package="your.packege" />
<context:property-placeholder location="classpath*:*.properties"/>
</beans>
The java class where you want inject properties values:
您要在其中注入属性值的 java 类：
public class ClassWithInjectedProperty {
@Value("${props.foo}")
private String foo;
}
