如何将外部xml文件推送到Spring Boot嵌入式tomcat Continer中

Question

i have created springboot project which gives fat-jar. i want to push external xml file in runtime into it.i want to place that xml file into spring-boot-tomcat container. tried many ways to do it (@import, --spring.config.location,etc) those ways didn't work out for me.

That xml file is ApplicationInsight.xml, which is used to post telemetry from our application to Azure portal.

Highly appreciate any help.

Answer 1

Based on the GitHJub issue, I think part of the problem is how you are passing JVM parameters, and how you are using "spring.config.location".

I am not familiar with Azure Insights really, but if I understand correctly, it is trying to load the ApplicationInsights.xml file to configure itself, and it's doing this automatically. So you really can't set it up in the WebConfigurerAdapter as I previously suggested because it has already initialized itself before that, correct? I left that part in anyways, but I get that it needs to be loaded sooner so I provided a few additional ways to add the file to the classpath ASAP.

New Stuff

First take a look at this line you had originally posted ala GitHub:

java -jar build/libs/file-gateway.jar --spring.config.location=classpath:/apps/conf/ApplicationInsight.xml 

Instead the value should be just a folder path, without "classpath" of "file" prefix. Also, try using '-D' instead of '--'.

java -jar build/libs/file-gateway.jar -Dspring.config.location=/apps/conf/

The property is supposed to either refer to a directory containing auto configuration property files for Spring Boot. It can also work for referring to a specific "application.properties|yml" file.

With that, my previous suggestion may work for you.

Old Suggestion

If you require a unique way for loading resources, you can add a resource handler to your application.

@Configuration
@EnableWebMvc
public class MvcConfig extends WebMvcConfigurerAdapter {

    @Value("${telemetry.folder}")
    private String telemetryFolder;

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry
          .addResourceLocations(telemetryFolder); 
    }
}

And/or you could load it with apache IO:

@Value("${telemetry.file}")
private String telemetryFile;

@Autowired
private ResourceLoader resourceLoader;

public String telemtryXml(){

    return org.apache.commons.io.IOUtils.toString(resourceLoader.getResource(telemtryFile).getInputStream());
}

But this will only work if the api you are using doesn't need to be initialized much earlier.

More New Stuff

In your last post on the GitHub issue, you tried this:

java -jar build/libs/file-gateway.jar -applicationinsights.configurationDirectory="/apps/conf/"

Instead, try adding the property as a jvm parameter like this:

java -jar build/libs/file-gateway.jar -Dapplicationinsights.configurationDirectory=/apps/conf/

Notice that I added a capital 'D' character after the, and I removed the quotes from the path.

Other ways to add the file to classpath are.

1. Add the directory to the JVM classpath.

   java -cp "build/libs/file-gateway.jar:/apps/conf/*" your.package.MainSpringBootApplication

This requires that you specify the main class which is (commonly) annotated with '@SpringBootApplication' and contains the main method. You do not execute the jar like before, but you do still add it to the classpath.

2. Forget about SpringBoot, and go back to your roots as a JEE developer. Add a "context.xml" for your app under the "src/main/resources/META-INF" folder, or "src/main/webapp/META-INF". I prefer the later if I'm building an executable war file, and the former for jars.

Example context.xml:

<?xml version='1.0' encoding='utf-8'?>
<!-- path should be the context-path of you application.
<Context path="/">
  <Resources className="org.apache.catalina.webresources.StandardRoot">
    <PreResources base="/apps/conf"
                  className="org.apache.catalina.webresources.DirResourceSet"
                  internalPath="/"
                  webAppMount="/WEB-INF/classes"/>
  </Resources>
</Context>

You can also use JVM parameters with EL.

So if you execute the jar with this:

java -jar build/libs/file-gateway.jar -Dapplicationinsights.configurationDirectory=/apps/conf/

You could set the resources base with this:

<!--snip -->
<PreResources base="${applicationinsights.configurationDirectory}" 
<!--snip -->

Hope that helps:)