You can use the ServletContext to obtain the real path of a resource file using the context path. 

Here's an example of how you can do that:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import javax.servlet.ServletContext;
import java.io.File;

@Component
public class ResourceFilePathProvider {

    private final ServletContext servletContext;

    @Autowired
    public ResourceFilePathProvider(ServletContext servletContext) {
        this.servletContext = servletContext;
    }

    public String getResourceFilePath(String relativePath) {
        String realPath = servletContext.getRealPath("/");
        String filePath = realPath + File.separator + relativePath;
        return filePath;
    }
}

In the example above, ResourceFilePathProvider is a Spring component that uses ServletContext to obtain the real path of a resource file. The getResourceFilePath method takes a relativePath parameter, which is the path to the resource file relative to the context path.

To use this component, inject an instance of ResourceFilePathProvider into your Spring components or controllers, and call the getResourceFilePath method, providing the relative path of the resource file. The method will return the absolute file path.

Here's an example usage in a controller:

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ResourceFileController {

    private final ResourceFilePathProvider resourceFilePathProvider;

    public ResourceFileController(ResourceFilePathProvider resourceFilePathProvider) {
        this.resourceFilePathProvider = resourceFilePathProvider;
    }

    @GetMapping("/resource/{fileName}")
    public String getResourceFilePath(@PathVariable String fileName) {
        String relativePath = fileName; // Assuming the file is in the context path
        return resourceFilePathProvider.getResourceFilePath(relativePath);
    }
}

In the above example, the ResourceFileController has a GET endpoint that takes a fileName path variable. It constructs the relative path by directly using the provided fileName. Then, it calls the getResourceFilePath method of ResourceFilePathProvider to retrieve and return the absolute file path of the specified resource file.

Please note that using the real path based on the context path may not always be recommended, especially in certain deployment scenarios. Ensure that you have proper access controls and security measures in place when working with file paths.