java - Spring 4.1.6.RELEASE : @RequestParam defaultValue and required=false don't affect

Question

我已经阅读了有关该问题的每个主题，并且我知道要在不设置 @RequestParam 的情况下使其余端点可用，需要在其中设置 required=false。我还了解到 4.1 版本中仍然存在一个错误，并且此参数不会影响 Controller 的行为，因此 defaultValue 参数应该可以完成这项工作。 但仍然对我不起作用:我尝试了 defaultValue 和 required，并且同时尝试了它们，我什至尝试了它们的不同顺序 - 我仍然得到Status 400 Bad Request 如果我不将这些参数放入获取地址中。 那么解决办法是什么呢？谢谢。 我的代码如下:

public class Controller {
@ResponseBody
    @RequestMapping(value = "/api/", params = { "param"}, method = RequestMethod.GET, produces = { "application/json" })
    public Results show(HttpServletRequest request, HttpServletResponse response,
            @RequestParam(value = "param", defaultValue = "all", required=false)) {
        return null;
    }
}

pom.xml 的一部分:

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${org.springframework-version}</version>
            <exclusions>
                <!-- Exclude Commons Logging in favor of SLF4j -->
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${org.springframework-version}</version>
            <scope>test</scope>
        </dependency>

和 web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
        org.springframework.web.context.support.AnnotationConfigWebApplicationContext
    </param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>


    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>com.demshin.medpro.configuration.WebAppConfiguration</param-value>
    </context-param>

    <servlet>
        <servlet-name>springServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextClass</param-name>
            <param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

和javaconfig:

@EnableWebMvc
@Configuration
@ComponentScan("com")
@Import(MySQLconfiguration.class)
public class WebAppConfiguration extends WebMvcConfigurerAdapter {

    @Bean
    public MappingJackson2HttpMessageConverter jacksonMessageConverter() {
        MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();

        ObjectMapper mapper = new ObjectMapper();
        // Registering Hibernate4Module to support lazy objects
        mapper.registerModule(new Hibernate4Module());

        messageConverter.setObjectMapper(mapper);
        return messageConverter;

    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        // Here we add our custom-configured HttpMessageConverter
        converters.add(jacksonMessageConverter());
        super.configureMessageConverters(converters);
    }

    @Bean
    @Description("Thymeleaf template resolver serving HTML 5")
    public ServletContextTemplateResolver templateResolver() {
        ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver();
        templateResolver.setPrefix("/WEB-INF/html/");
        templateResolver.setSuffix(".html");
        templateResolver.setTemplateMode("HTML5");
        return templateResolver;
    }

    @Bean
    @Description("Thymeleaf template engine with Spring integration")
    public SpringTemplateEngine templateEngine() {
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver());
        return templateEngine;
    }

    @Bean
    @Description("Thymeleaf view resolver")
    public ThymeleafViewResolver viewResolver() {
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setTemplateEngine(templateEngine());
        viewResolver.setContentType("text/html; charset=UTF-8");
        return viewResolver;
    }

    @Bean
    @Description("Spring message resolver")
    public ResourceBundleMessageSource messageSource() {
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        messageSource.setBasename("/WEB-INF/i18n/messages");
        return messageSource;
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/resources/**").addResourceLocations("/WEB-INF/resources/");
    }
}

Answer 1

问题是您在 @RequestMapping 级别中显式指定了 params = { "param"} ，该级别将继承到其较低级别。这意味着这应该出现在请求中。

对于有问题的示例:

    @ResponseBody
    @RequestMapping(value = "/api", params = { "param"},method = RequestMethod.GET, produces = { "application/json" })
    public String show(@RequestParam(value = "param", defaultValue = "all", required=false) String param, @RequestParam(value = "newparam", defaultValue = "all", required=false) String newparam) {
        return param+newparam;
    }

这里的newparam我声明为RequestParam并作为可选给出。所以请求:

http://localhost:8080/api?param=test

会起作用的。但是，如果我们在请求中避免 param ，它将给出 400，因为它已在 RequestMapping 中声明，因此它应该存在于请求。您需要在 RequestMapping 中或 @RequestParam 中指定请求参数。这意味着声明上述方法的正确方法是:

更正:

    @ResponseBody
    @RequestMapping(value = "/api", params = { "param"},method = RequestMethod.GET, produces = { "application/json" })
    public String show(String param, @RequestParam(value = "newparam", defaultValue = "all", required=false) String newparam) {
        return param+newparam;
    }

解决您的问题的简单方法是从 @RequestMapping 中删除 params = { "param"}

所以我不认为这是 Spring 的错误