@Value – >无法将’java.lang.String’类型的值转换为必需类型’java.lang.Integer’

美好的一天，我正在使用Spring 4.1.1.RELEASE开发Web应用程序。 所有Spring配置都是用注释完成的，除了一件事之外它工作得很好：

• 我在项目中有这些行的config.properties文件

  cases.caseList.filter=test cases.caseList.numberOfCasesPerPage=50 

• 我有一个配置类

   @Configuration @ComponentScan(basePackageClasses={CaseConfig.class}) @PropertySource(value = "classpath:config.properties") public class CasesModuleTestContextConfig { ... } 

• 另一堂课

   @Component public class HttpRequestParamsToPaginationParams extends AbstractConverter<Map, PaginationParams> { @Value("${cases.caseList.filter}") private String filter; @Value("${cases.caseList.numberOfCasesPerPage}") private Integer count; ... } 

属性“filter”的值是从属性资源中成功注入的。 但我在财产’计数’上得到例外：

  13:58:45.274 [main] WARN oscsGenericApplicationContext - Exception encountered during context initialization - cancelling refresh attempt org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'cz.pokus.core.test.config.ConversionServiceTestConfig': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.util.List cz.pokus.core.test.config.ConversionServiceTestConfig.converterList; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'httpRequestParamsToPaginationParams': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.lang.Integer cz.pokus.core.cases.converter.HttpRequestParamsToPaginationParams.count; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer'; nested exception is java.lang.NumberFormatException: For input string: "${cases.caseList.numberOfCasesPerPage}" at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) ~[spring-beans-4.1.1.RELEASE.jar:4.1.1.RELEASE] ... Caused by: org.springframework.beans.TypeMismatchException: Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer'; nested exception is java.lang.NumberFormatException: For input string: "${cases.caseList.numberOfCasesPerPage}" ... Caused by: java.lang.NumberFormatException: For input string: "${cases.caseList.numberOfCasesPerPage}" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) ~[na:1.8.0_20] at java.lang.Integer.parseInt(Integer.java:569) ~[na:1.8.0_20] at java.lang.Integer.valueOf(Integer.java:766) ~[na:1.8.0_20] ... 

当我将属性’count’的类型更改为String时，它开始工作：

  @Value("${cases.caseList.numberOfCasesPerPage}") private String count; 

我相信Spring能够在使用@Value将属性资源的值注入Integer属性时将String转换为Integer。 我找到了人们在没有抱怨的情况下使用的例子。 你有任何想法，为什么它对我不起作用？

非常感谢提前。

Answer 1

如果您尝试使用@Value("")注释访问属性值，则应声明PropertySourcesPlaceholderConfigurer Bean。

尝试在配置类中添加以下代码段。

 @Bean public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() { return new PropertySourcesPlaceholderConfigurer(); } 

如果您不想声明它，请尝试使用org.springframework.core.env.Environment类，在类中自动assembly它，以获取属性值。

 @Autowired private Environment environment; public void readValues() { System.out.println("Some Message:" + environment.getProperty("")); }