Java 在 Spring 中注入静态常量的值
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Injecting values for static constants in Spring
提问by Shyam
In one of my classes there is a public static Stringmember and I need set this value in the applicationContext.xml! That is, is it possible for us to inject a value for this static property?
在我的一个班级中有一个public static String成员，我需要在 applicationContext.xml! 也就是说，我们可以为这个静态属性注入一个值吗？
采纳答案by JoseK
yes there is an example on this link http://planproof-fool.blogspot.com/2010/03/spring-setting-static-fields.html
是的，此链接上有一个示例http://planproof-fool.blogspot.com/2010/03/spring-setting-static-fields.html
回答by Espen
No, it's not possible to inject a value to a static field from your XML context.
不，不可能从 XML 上下文向静态字段注入值。
If you can modify the class, you have the following simple choices:
如果您可以修改类，您有以下简单的选择：
- remove the static modifier and add @Inject/@Autowire above the field
- add a constructor/setter/init method.
- 删除静态修饰符并在字段上方添加@Inject/@Autowire
- 添加构造函数/setter/init 方法。
Else, you can do it with Spring's Java configuration support.
否则，您可以使用 Spring 的 Java 配置支持来实现。
An example:
一个例子：
The Demo class with the static field and a JUnit method that asserts that the Spring container injects the wanted value into the static field:
带有静态字段和 JUnit 方法的 Demo 类断言 Spring 容器将所需的值注入静态字段：
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("test-context.xml")
public class Demo {
public static String fieldOne;
@Test
public void testStaticField() {
assertEquals("test", fieldOne);
}
}
Add the context namespace to your applicationContext and component-scan element:
将上下文命名空间添加到您的 applicationContext 和 component-scan 元素：
<context:component-scan base-package="com.example" />
Add your bean with the static field like the this:
添加带有静态字段的 bean，如下所示：
@Configuration
public class JavaConfig {
@Bean
public Demo demo() {
Demo.fieldOne = "test";
return new Demo();
}
}
In this case, the JavaConfig class must be in the com.example package as declared in the component-scan element.
在这种情况下，JavaConfig 类必须在组件扫描元素中声明的 com.example 包中。
