spring-mvc - 如何为 URL 的数据库查找构建 spring mvc 自定义处理程序映射

Question

在我的应用程序中，管理员用户可以控制项目的 URL，所以我想在数据库中查找注册的 URL，并重定向到相关的 Controller 方法。

我想弄清楚在某些情况下我应该返回什么:

1. 缺少 URL - 我想抛出 404 错误。
2. URL 已重定向 - 我想返回状态 301，重定向返回响应。
3. URL 没问题 - 我想将 URL 重定向到相关的 Controller 。

值得注意的是， Controller 方法已经使用标准的请求映射，例如 /products/{productId}，并且解析良好。

在代码中，它找到了 URL，我可以确定它是产品、页面等。但是我不确定如何重定向到 Controller 方法，或者 URL 是否被重定向或不存在如何分别返回错误码301或404...

有人能帮忙吗？

@Component
public class SeoUrlHandlerMapping extends AbstractUrlHandlerMapping {

    private static Logger logger = LogManager.getLogger(SeoUrlHandlerMapping.class.getName());

    @Autowired
    private ProductSeoService productSeoService;
    /**
     * Looks up the handler for the url path.
     * @param urlPath the URL path
     * @param request the request.
     * @return
     * @throws Exception
     */
    @Override
    protected Object lookupHandler(String urlPath, HttpServletRequest request) throws Exception {

        logger.entry("looking up handler for path: " + urlPath);

        // this is just a test.
        SeoUrl productUrl = productSeoService.findByURL(urlPath);
        if (productUrl instanceof ProductSeoUrl)
        {
            ProductSeoUrl productSeoUrl = (ProductSeoUrl) productUrl;
            logger.debug("Handling request to product  " + productSeoUrl.getProduct());
            request.setAttribute("id", productSeoUrl.getProduct().getId());
            return getApplicationContext().getBeansOfType(ProductWebController.class);
        }
        return null;
    }
}

Answer 1

好的，没有答案，但我会发布我最终得出的结论。我不确定这是否是最好的解决方案，但它似乎对我来说没问题。可能有更好的方法来设置模型映射或重写路径参数，但 servlet 请求工作正常...

所以这是主要的 MappingHandler:

/**
 * The SeoUrlHandlerMapping will map between SEO URL requests and controller method
 */
@Component
public class SeoUrlHandlerMapping extends RequestMappingHandlerMapping {

    private static Logger logger = LogManager.getLogger(SeoUrlHandlerMapping.class.getName());

    @Autowired
    private ProductSeoService productSeoService;

    private final Map<String, HandlerMethod> handlerMethods = new LinkedHashMap<String, HandlerMethod>();


    @Override
    protected void initHandlerMethods() {

       logger.debug("initialising the handler methods");
        String[] beanNames =
                getApplicationContext().getBeanNamesForType(Object.class);

        for (String beanName : beanNames) {
            Class clazz = getApplicationContext().getType(beanName);
            final Class<?> userType = ClassUtils.getUserClass(clazz);

            if (isHandler(clazz)){
                for (Method method: clazz.getMethods())
                {
                    SeoUrlMapper mapper = AnnotationUtils.getAnnotation(method, SeoUrlMapper.class);
                    if (mapper != null)
                    {
                        RequestMappingInfo mapping = getMappingForMethod(method, userType);
                        HandlerMethod handlerMethod = createHandlerMethod(beanName, method);
                        this.handlerMethods.put(mapper.seoType(), handlerMethod);
                    }
                }
            }
        }
    }

    /**
     * {@inheritDoc}
     * Expects a handler to have a type-level @{@link org.springframework.stereotype.Controller} annotation.
     */
    @Override
    protected boolean isHandler(Class<?> beanType) {
        return ((AnnotationUtils.findAnnotation(beanType, Controller.class) != null) ||
                (AnnotationUtils.findAnnotation(beanType, RequestMapping.class) != null));
    }

    /**
     * The lookup handler method, maps the SEOMapper method to the request URL.
     * <p>If no mapping is found, or if the URL is disabled, it will simply drop throug
     * to the standard 404 handling.</p>
     * @param urlPath the path to match.
     * @param request the http servlet request.
     * @return The HandlerMethod if one was found.
     * @throws Exception
     */
    @Override
    protected HandlerMethod lookupHandlerMethod(String urlPath, HttpServletRequest request) throws Exception {

        logger.entry("looking up handler for path: " + urlPath);

        // this is just a test.
        SeoUrl productUrl = productSeoService.findByURL(urlPath);
        if (productUrl instanceof ProductSeoUrl) {
            ProductSeoUrl productSeoUrl = (ProductSeoUrl) productUrl;

            if (productSeoUrl.getStatus().equals(SeoUrlStatus.OK) || productSeoUrl.getStatus().equals(SeoUrlStatus.DRAFT))
            {
                request.setAttribute(SeoConstants.ID, productSeoUrl.getProduct().getId());
                request.setAttribute(SeoConstants.URL_STATUS, productSeoUrl.getStatus().toString());
                return this.handlerMethods.get("PRODUCT");
            }else if (productSeoUrl.getStatus().equals(SeoUrlStatus.REDIRECTED))
            {
                request.setAttribute(SeoConstants.REDIRECT_URL, productSeoUrl.getRedirectURL());
                return this.handlerMethods.get("REDIRECT");
            }

            // otherwise we let it return 404 by dropping through.
        }

        return null;
    }
}

然后我在 Controller 方法上使用自定义注释来隔离处理程序方法:

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface SeoUrlMapper {
        /**
         * Assigns a type to this mapping.
         * <p><b>This should match the SEOEntityType constants</b></p>.
         */
        String seoType();
}

最后，在我的 Controller 方法中，我设置了注释来指示方法:

@SeoUrlMapper(seoType = "REDIRECT")
public RedirectView issueRedirect(ModelMap map, HttpServletRequest request)
{
    logger.entry();
    RedirectView view = new RedirectView();
    view.setStatusCode(HttpStatus.MOVED_PERMANENTLY);
    view.setUrl((String)request.getAttribute("REDIRECT_URL"));
    view.setExposeModelAttributes(false);
    logger.exit();
    return view;
}

@SeoUrlMapper(seoType = "PRODUCT")
public String viewProductInternal(ModelMap map, HttpServletRequest request)
{
    Long id = (Long) request.getAttribute(SeoConstants.ID);
    Product product = productService.findForDetailView(id);
    return commonViewProduct(product, map);
}