How to Use @PathVariable and Map Static Resources in Spring Boot

1. Scenario

Different paths trigger different methods. For example, in a video site, different modules are invoked based on the path.

2. Usage

@PathVariable indicates that the parameter should be obtained from the URL path.

<code>// Wrap the required parameter with curly braces
@RequestMapping("/video/{v}")
// The called method receives the parameter using @PathVariable
public void function(@PathVariable String v) {};
</code>

3. Static Resource Mapping

By default, Spring Boot serves static resources (images, videos, etc.) from the static folder. To serve files from a local directory, use a static resource mapping. Adding the following code to the main application class maps the URL path /img/** to a local folder. Note that the class implements WebMvcConfigurer .

<code>@SpringBootApplication
public class Application implements WebMvcConfigurer {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        // URL path                Disk path
        registry.addResourceHandler("/img/**")
                .addResourceLocations("file:E:\\Java\\project1\\img\\");
    }
}
</code>

4. Global Configuration

If a value (e.g., a path) is used in multiple places, it can be maintained centrally in a configuration file.

<code>img-path = E:/Java/project1/img/
</code>

Inject the configured value in code:

<code>@Value("${img-path}") // Read the value from the configuration file
private String imgPath;
</code>