SpEL如何在方法调用中使用参数？

Question

我有一个使用Spring Scheduler的应用程序，我想从数据库中获取cron表达式。我没有参数就可以使用它，但是在调用中需要一个参数才能从数据库中获取正确的时间表（时间表名称）。我尝试了几种不同的版本，但没有成功。请查看下面的工作代码和非工作代码，以作为我要执行的操作的示例。

以下代码正在工作：

@Configuration
@EnableScheduling
public class ApplicationConfig {

    @Autowired
    SchedulePropertiesRepository spRepository;

    @Bean   
    public String getCronExpression() {
        ScheduleProperties sp = spRepository.findByScheduleName("date");
        return sp.getCron();
    }
}

和

@Scheduled(cron = "#{@getCronExpression}")
private void cronSchedule() {
     log.info("The time is now {}", dateFormat.format(new Date()));
}

但是我想为时间表名称传递参数，例如：

@Configuration
@EnableScheduling
public class ApplicationConfig {

    @Autowired
    SchedulePropertiesRepository spRepository;

    @Bean   
    public String getCronExpression(String scheduleName) {
        ScheduleProperties sp = spRepository.findByScheduleName(scheduleName);
        return sp.getCron();
    }
}

和

@Scheduled(cron = "#{@getCronExpression('date')}")
private void cronSchedule() {
     log.info("The time is now {}", dateFormat.format(new Date()));
}

但是这是我以下例外：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scheduler' defined in file [C:\git\WV_Global_Common.GeniusPrintDocExtractor\target\classes\com\chubb\GeniusPrintDocExtractor\config\Scheduler.class]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelParseException: EL1041E: After parsing a valid expression, there is still more data in the expression: 'lparen(()'
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:603) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:879) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at com.chubb.GeniusPrintDocExtractor.GeniusPrintDocExtractorApplication.main(GeniusPrintDocExtractorApplication.java:12) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_241]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_241]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_241]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_241]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.2.5.RELEASE.jar:2.2.5.RELEASE]
Caused by: org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelParseException: EL1041E: After parsing a valid expression, there is still more data in the expression: 'lparen(()'
    at org.springframework.context.expression.StandardBeanExpressionResolver.evaluate(StandardBeanExpressionResolver.java:164) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.config.EmbeddedValueResolver.resolveStringValue(EmbeddedValueResolver.java:56) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.processScheduled(ScheduledAnnotationBeanPostProcessor.java:412) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.lambda$null$1(ScheduledAnnotationBeanPostProcessor.java:362) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at java.lang.Iterable.forEach(Iterable.java:75) ~[na:1.8.0_241]
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.lambda$postProcessAfterInitialization$2(ScheduledAnnotationBeanPostProcessor.java:362) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_241]
    at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.postProcessAfterInitialization(ScheduledAnnotationBeanPostProcessor.java:361) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:431) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    ... 20 common frames omitted
Caused by: org.springframework.expression.spel.SpelParseException: EL1041E: After parsing a valid expression, there is still more data in the expression: 'lparen(()'
    at org.springframework.expression.spel.standard.InternalSpelExpressionParser.doParseExpression(InternalSpelExpressionParser.java:135) ~[spring-expression-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.expression.spel.standard.SpelExpressionParser.doParseExpression(SpelExpressionParser.java:61) ~[spring-expression-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.expression.spel.standard.SpelExpressionParser.doParseExpression(SpelExpressionParser.java:33) ~[spring-expression-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.expression.common.TemplateAwareExpressionParser.parseExpressions(TemplateAwareExpressionParser.java:121) ~[spring-expression-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.expression.common.TemplateAwareExpressionParser.parseTemplate(TemplateAwareExpressionParser.java:62) ~[spring-expression-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.expression.common.TemplateAwareExpressionParser.parseExpression(TemplateAwareExpressionParser.java:49) ~[spring-expression-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.context.expression.StandardBeanExpressionResolver.evaluate(StandardBeanExpressionResolver.java:142) ~[spring-context-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    ... 30 common frames omitted

有没有一种方法可以满足我的要求？

Answer 1

@getCronExpression不是方法调用，而是按名称引用bean。参见Spring documentation。

相反，删除@Bean批注，命名配置bean，以便您可以引用它，然后调用该方法。

@Configuration("myApplicationConfig")
@EnableScheduling
public class ApplicationConfig {

    @Autowired
    SchedulePropertiesRepository spRepository;

    public String getCronExpression(String scheduleName) {
        ScheduleProperties sp = spRepository.findByScheduleName(scheduleName);
        return sp.getCron();
    }
}

和

@Scheduled(cron = "#{@myApplicationConfig.getCronExpression('date')}")
private void cronSchedule() {
     log.info("The time is now {}", dateFormat.format(new Date()));
}