Spring PropertySourcesPlaceholderConfigurer beans：在運行時解析屬性值

Question

我正在使用多個PropertySourcesPlaceholderConfigurer bean 加載屬性並設置占位符前綴：

@Bean
public static PropertySourcesPlaceholderConfigurer fooPropertyConfigurer() {
    PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer = new PropertySourcesPlaceholderConfigurer();
    propertySourcesPlaceholderConfigurer.setLocation(new ClassPathResource("foo.properties"));
    propertySourcesPlaceholderConfigurer.setIgnoreResourceNotFound(true);
    propertySourcesPlaceholderConfigurer.setPlaceholderPrefix("$foo{");
    return propertySourcesPlaceholderConfigurer;
}

雖然我可以通過指定它的索引和鍵來注入屬性值，如下所示：

@Value("$foo{key}")
private String value;

有時我需要在運行時確定前綴 ('foo') 的值並動態解析屬性值。 這可能嗎？ 如果不是，那么針對此用例推薦哪些替代解決方案？

Answer 1

感謝這篇文章，我找到了一個解決方案：

@Component
public class PropertyPlaceholderExposer implements BeanFactoryAware {  
    
    ConfigurableBeanFactory beanFactory; 

    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        this.beanFactory = (ConfigurableBeanFactory) beanFactory;
    }

    public String resolveProperty(String prefix, String key) {
        String rv = beanFactory.resolveEmbeddedValue("$" + prefix + "{" + key + "}");
        return rv;
    }

}

用法：

@Autowired
private PropertyPlaceholderExposer ppe;
    
{
    String v = ppe.resolveProperty("bar", "key");
}