从spring boot runtime Application.properties动态填充.js属性的最佳方法？

Question

我们有一个微型应用程序，它由前端开发人员组装起来，然后“翻墙而去”。它定义了一个属性文件settings.js：

var SERVERROOT = 'http://solr:8983/solr/operations/select/';

由html引用：

 <script type='text/javascript' src="js/settings.js"></script>

我想在运行时在application.yml中定义solr路径，如下所示：

app:    
   solr:
      path: 'http://solr:8983/solr/operations/select/'

 -Dapp.solr.path=...

）

可能

我曾考虑将'settings.js'作为一个Tymeleaf模板（settings.js.html)，并让一个spring控制器从application.properties填充模型。

Answer 1

您可以使用ResourceTransformer：

@Component
public class InjectSolrPathResourceTransformer implements ResourceTransformer {
    private final MySetting settings; // inject via constructor

    @Override
    public Resource transform(HttpServletRequest request, Resource resource, ResourceTransformerChain transformerChain) throws IOException {
if (request.getServletPath().equals("/js/settings.js")) {
            byte[] bytes = FileCopyUtils.copyToByteArray(resource.getInputStream());
            String content = new String(bytes, StandardCharsets.UTF_8);
            content = content.replace("var SERVERROOT = SERVERROOT_VALUE",
                                      "var SERVERROOT = '" + settings.getSolrPath() + "'");

            return new TransformedResource(resource, content.getBytes(StandardCharsets.UTF_8));
        } else {
            return resource;
        }
    }
}

这假设您将settings.js更改为：

var SERVERROOT = SERVERROOT_VALUE

要使用ResourceTransformer，请在WebMVCConfigureer中注册它：

@Configuration
public class WebConfig implements WebMvcConfigurer {

    // inject this via constructor
    private final InjectSolrPathResourceTransformer resourceTransformer;

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/js/**")
                .addResourceLocations("classpath:/public/js/")
                .addTransformer(resourceTransformer);
    }
}