Spring 4.1.6.RELEASE：@RequestParam defaultValue和required = false不影响

Question

I've read every topic about the issue and I got to know that to make the rest endpoint available without setting @RequestParam one needs to set in it required=false . I also got to know that there is a bug still available in version 4.1, and this parameter doesn't affect the behaviour of a controller, so defaultValue parameter should do the job. And still neither works for me: I tried each of defaultValue and required , and both of them at the same time, and I even tried different order of them - I still get Status 400 Bad Request if I don't put those parameters in the get address. So what's the solution? Thanks. My code is below:

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;
    }
}

Part of pom.xml:

        <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>

and 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>

and 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

The problem is you have specified params = { "param"} explicitly in the @RequestMapping level, which will be inherited to its lower levels. That means this should be there in the request.

For problematic example:

    @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;
    }

Here the newparam I declared as RequestParam and given as optional.So the request:

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

will work. But if we avoid param from the request it will give 400 , since which is declared already in the RequestMapping , so it should be there in the request. You need to specify request param either in RequestMapping or as @RequestParam . That means the correct way to declare above method would be:

Corrected:

    @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;
    }

In brief solution to your problem is remove params = { "param"} from @RequestMapping

So I dont think it is a bug of Spring