Question

我正在使用spring应用程序，我正在尝试使用@Value注释从属性文件加载属性，但变量始终为null。

以下是我使用Annotated变量的代码：

@Service
public class RulesEngineServiceImpl implements IRulesEngineService {
 @Value("${display.property}") static String displayProperty;
 @Value("${return.enabled}") static boolean returnEnabled;
 @Value("${return.type}") static String returnType;
 @Value("${immediaterpi}") static boolean immediaterpi;

 private static Rule getDefaultRule() {
    LOG.info("applying default rule displayProperty ="+displayProperty+"|  returnEnabled="+returnEnabled+"| returnType="+returnType+" | immediaterpi="+immediaterpi);
    Rule rule = new Rule();
    rule.setName("DEFAULT_RULE");
    rule.setDisplayProperty(DisplayProperty.valueOf(displayProperty));
    ActionProperty actionProperty = new ActionProperty();
    ReturnActionVO returnAction = new ReturnActionVO(returnEnabled, returnType, immediaterpi);
    actionProperty.setActions(JSONUtils.writeJson(returnAction));
    rule.setActionProperty(actionProperty);
    return rule;
 }
}

这是名为application.prop的属性文件，其中定义了这些文件：

display.property=xzc
return.enabled=false
return.type=""
immediaterpi=false

我在这里提供了这个文件的参考：

@PropertySources({
    @PropertySource("classpath:application.prop")})
public class PieApplication extends SpringBootServletInitializer 
{

 @Bean
 public PieServletContextListener pieServletContextListener() {
    return new PieServletContextListener();
 } 

 public static void main(String[] args) throws Exception {
    SpringApplication.run(PieApplication.class, args);
 }

}

但是当我从其他代码中调用方法getDefaultRule()时，它不会加载像displayProperty这样的变量并打印日志如下：

applying default rule displayProperty =null|  returnEnabled=false| returnType=null | immediaterpi=false

请咨询。

修改下面是代码更改，以防我使它们成为非静态

@Value("${display.property}")  String displayProperty;
@Value("${return.enabled}") boolean returnEnabled;
@Value("${return.type}")  String returnType;
@Value("${immediaterpi}")  boolean immediaterpi;

private static Rule getDefaultRule() {
    RulesEngineServiceImpl rulesEngineService = new RulesEngineServiceImpl();

    LOG.info("applying default rule displayProperty ="+rulesEngineService.displayProperty+"|  returnEnabled="+rulesEngineService.returnEnabled+"| returnType="+rulesEngineService.returnType+" | immediaterpi="+rulesEngineService.immediaterpi);
    Rule rule = new Rule();
    rule.setName("DEFAULT_RULE");
    rule.setDisplayProperty(DisplayProperty.valueOf(rulesEngineService.displayProperty));
    ActionProperty actionProperty = new ActionProperty();
    ReturnActionVO returnAction = new ReturnActionVO(rulesEngineService.returnEnabled, rulesEngineService.returnType, rulesEngineService.immediaterpi);
    actionProperty.setActions(JSONUtils.writeJson(returnAction));
    rule.setActionProperty(actionProperty);
    return rule;
}

但结果仍然相同。我的问题是该字段何时初始化？如何从静态方法访问它，因为访问它的方法不能是非静态的？

Answer 1

您不能在静态字段上使用@Value。使该字段非静态。

Answer 2

默认情况下，Spring bean是单例，而使用@Value注释的字段只会设置一次。因此，不需要将它们定义为静态字段。此外，在单元测试期间，非静态字段更容易被模拟。

@Value Annotation不起作用

2 个答案: