春天@MatrixVariable

Question

最近我正在尝试使用Spring开发简单的Web应用程序。不幸的是，昨天我遇到了一个我自己无法解决的问题：

1。引言

我有以下方法，从URL收集价格范围：

   @RequestMapping("/filter/price/{price}")
    public String getProductsByPrice(Model model, @MatrixVariable(pathVar = "price") Map<String, Integer> filterParams) {

        model.addAttribute("items", productService.getProductsByPriceFilter(filterParams));

        return PRODUCTS;
    }

网址为 http://localhost:8080/webstore/products/filter/price/price;LOW=200;HIGH=900

这是 getProductsByPriceFilter 方法的实现：

@Override
    public Set<Product> getProductsByPriceFilter(Map<String, Integer> filterParams) {

        Set<Product> productsByPrice = new HashSet<>();
        Set<String> criterias = filterParams.keySet();

        // start of the problem
        BigDecimal minimalPrice = new BigDecimal(filterParams.get("LOW"));
        BigDecimal maximalPrice = new BigDecimal(filterParams.get("HIGH"));
        //end of the problem

        if (criterias.contains(LOW) && criterias.contains(HIGH)) {
            for (Product product : listOfProducts) {
                if ((minimalPrice.compareTo(product.getUnitPrice()) == -1) && (maximalPrice.compareTo(product.getUnitPrice()) == 1)) {
                    productsByPrice.add(product);
                }
            }
        } else if (criterias.contains(LOW)) {
            for (Product product : listOfProducts) {
                if ((minimalPrice.compareTo(product.getUnitPrice()) == -1)) {
                    productsByPrice.add(product);
                }
            }
        } else if (criterias.contains(HIGH)) {
            for (Product product : listOfProducts) {
                if ((maximalPrice.compareTo(product.getUnitPrice()) == 1)) {
                    productsByPrice.add(product);
                }
            }
        }

        return productsByPrice;
    }

2。问题

在上面的方法中，我标记了代码片段，其中出现了以下错误（当尝试获取＆＃34; LOW＆＃34;键和＆＃34; HIGH＆＃34;键的值）时：

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.ClassCastException: java.util.LinkedList cannot be cast to java.lang.Integer
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:973)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
root cause

java.lang.ClassCastException: java.util.LinkedList cannot be cast to java.lang.Integer
    com.packt.webstore.domain.repository.impl.InMemoryProductRepository.getProductsByPriceFilter(InMemoryProductRepository.java:129)
    com.packt.webstore.service.impl.ProductServiceImpl.getProductsByPriceFilter(ProductServiceImpl.java:46)
    com.packt.webstore.controller.ProductController.getProductsByPrice(ProductController.java:78)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

3。问题

有人可以告诉我如何使用我的方法从最初提到的URL中提取所需的值（以下键的值：HIGH和LOW）？我正在尝试使用streams（）等，但不幸的是每次我都遇到同样的例外。