Spring PropertySourcesPlaceholderConfigurer beans：在运行时解析属性值

Question

我正在使用多个PropertySourcesPlaceholderConfigurer bean 加载属性并设置占位符前缀：

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

虽然我可以通过指定它的索引和键来注入属性值，如下所示：

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

有时我需要在运行时确定前缀 ('foo') 的值并动态解析属性值。 这可能吗？ 如果不是，那么针对此用例推荐哪些替代解决方案？

Answer 1

感谢这篇文章，我找到了一个解决方案：

@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");
}