Spring Boot images uploading and serving

问题:

I'm making new Spring Boot app and want to be able to store and serve images, I want images to be stored in applications directory showed here

this is what uploading looks like for now:

@PostMapping("/")
@ResponseBody
public String upload(@RequestPart String title, @RequestPart MultipartFile img) throws IOException{
    String imgName = img.getOriginalFilename();
    Post p = new Post();
    p.setTitle(title);
    p.setImageName(imgName);
    postService.add(p);
    File upl = new File("images/" + imgName);
    upl.createNewFile();
    FileOutputStream fout = new FileOutputStream(upl);
    fout.write(img.getBytes());
    fout.close();
    return "ok";
}

this is how I want to get images

<img th:src="@{'images/' + ${post.imageName}}"/>

for now I get 404 and when I want to view some images in directory I get

Fatal error reading PNG image file: Not a PNG file

how should I do it to make it work?

回答1:

Per default your Spring Boot application serves static content - in your case images - found at following locations:

• /static
• /public
• /resources
• /META-INF/resources

So usually, static/images/ would perhaps be the place where Thymeleaf should expect the static images which have to be delivered for rendering. But since this place is about static content and since it is in general a bad idea to save uploaded (dynamic) content inside your application I would recommend to DON'T do that. Did you think about what happens if your application is redeployed or moved to another machine? Your would have to backup / move the images in a cumbersome way. There are better solutions, storing the upload content at a separate location outside your app (which could for example be configurable and also reused by multiple instances) or even use a database to store image data. That would also enable handling images in a transactional context (e.g. isolation & rollbacks).

But If you now want to still store it inside your app, your can extend the locations by adding places to search for (actually static content). Although the answer of Ajit and even the documentation still gives the advice to extend your own WebMvcConfigurerAdapter, I personally would tend to implement WebMvcConfigurer instead, because the former is deprecated.

In this case it should look like:

@Configuration
public class AdditionalResourceWebConfiguration implements WebMvcConfigurer {
    @Override
    public void addResourceHandlers(final ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/images/**").addResourceLocations("file:images/");
    }
}

回答2:

To access image from your images folder,

You need to override addResourceHandlers method of WebMvcConfigurerAdapter class like this:

@Configuration
public class ResourceConfig extends WebMvcConfigurerAdapter {
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/images/**").addResourceLocations("file:images/");
    }
}

After that you need add / before images in URL like this:

<img th:src="@{'/images/' + ${post.imageName}}"/>

回答3:

You can store external files in a folder named /static in the same directory as your jar and spring will scan them by default. So if you have static/images/ you can reference your images with:

<img th:src="@{/images/img.ext}"/>

So you would want to use new File("/static/images/" + imgName);