Spring的@RequestBody在POST上提供空字符串

Question

我有一个Spring 3.0.5.RELEASE的应用程序试图使用@RequestBody获取帖子的完整内容.调用该方法,但传递的字符串始终为空.我通过放置断点检查了StringHttpMessageConverter是否被调用,但内部HttpInputMessage是空的.

我已经看过Jetty和Tomcat的这个问题,所以我放弃了容器的问题.

这是我的样本控制器:

@Controller
@RequestMapping("/")
public class SubscriptionController {
    @RequestMapping(value = "/requestbody", method = RequestMethod.POST)
    public ModelAndView mycustomAction(@RequestBody String body) {

        // body is always empty
        Logger.getLogger(this.getClass()).debug("REQUEST BODY '" + body + "'");
        return new ModelAndView("empty");
    }
}

我的应用程序上下文定义如下:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

    <!-- Enable auto detection of controllers -->
    <context:component-scan base-package="com.big.viajerotelcel.controller" />

    <!--
        use annotation driven mvc and one single validator with JSR-303
        standard
    -->
    <mvc:annotation-driven />

    <!--
        Message source for this context, loaded from localized "messages_xx"
        files
    -->

    <bean id="messageSource"
        class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
        <property name="basenames" value="classpath:i18n/messages" />
        <property name="defaultEncoding" value="UTF-8" />
    </bean>

    <!-- Declare the Interceptor -->
    <mvc:interceptors>
        <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor"
            p:paramName="locale" />
    </mvc:interceptors>

    <!-- Declare the Resolver -->
    <bean id="localeResolver"
        class="org.springframework.web.servlet.i18n.SessionLocaleResolver" />

    <!-- will load Tiles definitions! -->
    <bean id="tilesConfigurer"
        class="org.springframework.web.servlet.view.tiles2.TilesConfigurer">
        <property name="definitions">
            <list>
                <value>/WEB-INF/general.xml</value>
            </list>
        </property>
    </bean>

    <!-- Tiles view resolver -->
    <bean id="viewResolver"
        class="org.springframework.web.servlet.view.UrlBasedViewResolver">
        <property name="viewClass"
            value="org.springframework.web.servlet.view.tiles2.TilesView" />
    </bean>

    <!-- Configure the multipart resolver -->
    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!--
            one of the properties available; the maximum file size in bytes (5MB)
        -->
        <property name="maxUploadSize" value="5120000" />
    </bean>

    <!-- Adding these lines has no effect, the StringHttpMessageConverter is called either way -->
<!--    <bean id="stringHttpMessageConverter" class="org.springframework.http.converter.StringHttpMessageConverter"/>-->
<!--           -->
<!--    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">-->
<!--        <property name="messageConverters">-->
<!--          <list>-->
<!--            <ref bean="stringHttpMessageConverter"/>-->
<!--          </list>-->
<!--        </property>-->
<!--    </bean>-->
</beans>

我正在使用curl测试这个,如下所示:

curl -d asd = 123 -d qwe = 456 http:// localhost:8080/requestbody

任何想法或帮助都受到欢迎!

Answer 1

这是一个ServletServerHttpRequest扩展的代码片段HttpInputMessage.我非常肯定这是您在代码中使用的实现:

public InputStream getBody() throws IOException {
    return this.servletRequest.getInputStream();
}

换句话说,请求主体意味着被读取为HttpServletRequest对象的输入流.

请求的输入流在几种情况下无效,但我目前找不到正确的文档.例如,如果你调用request.getParameter()一个post请求,tomcat必须读取输入流才能解释参数,因此当你读取输入流时,它是空的,因为它已经到了最后.

也许你是getParameter在拦截器中调用某个地方,或者是在web.xml中定义的过滤器.另一个选择是Spring正在为你做这件事,例如,如果你的控制器有一些其他复杂@RequestMapping的方法(比如读取参数值或标题值).

我有两个建议:

1. 添加一个servlet过滤器(在spring有机会行动之前),并用你自己的包装器包装请求(只需扩展HttpServletRequestWrapper).这样,您可以在请求对象的某些方法中放置断点或日志消息,并查看谁在调用它们.

2. 使用pojo对象参数,并设置绑定.这似乎是一种更清晰的阅读帖子数据的方式.