使用Spring WebFlow 2.4.0上载文件，参数未绑定

Question

我使用的是Spring Framework 4.1.5,Spring Security 4.0.0.rc2,Spring Webflow 2.4.0.release和Tomcat 8.0.15。

我遵循了webflow文档中的示例，但无法在表单bean中获取文件。

表单

    <form:form action="${flowExecutionUrl}" method="post" commandName="fileForm" enctype="multipart/form-data">
        <form:input type="file" value="" path="multipartFileUpload"/>
        <button type="submit" name="_eventId_forward"><spring:message code="signup.forward"/></button>
        <sec:csrfInput/>
    </form:form>

public class FileForm implements Serializable {
    private static final long serialVersionUID = 1L;

    private transient MultipartFile multipartFileUpload;

    public MultipartFile getMultipartFileUpload() {
        return multipartFileUpload;
    }

    public void setMultipartFileUpload(final MultipartFile multipartFileUpload) {
        this.multipartFileUpload = multipartFileUpload;
    }
}

<view-state id="companyLogo" view="signup/company-logo" model="fileForm">
    <var name="fileForm" class="it.openex.pmcommonw.form.FileForm"/>
    <transition on="back" to="chooseProfile" bind="false" validate="false"/>
    <transition on="forward" to="companyInfo">
        <evaluate expression="userCommonBean.uploadImage(fileForm)"/>
    </transition>
</view-state>

@Component
public class UserCommonBean {    
    public static void uploadImage(final FileForm fileForm) throws IOException, ServletException {
        fileForm.getMultipartFileUpload(); // always null!!!
    }
}

multipartResolver

@Bean
public CommonsMultipartResolver filterMultipartResolver() {
    final CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
    multipartResolver.setMaxUploadSize(10 * 1024 * 1024);
    multipartResolver.setMaxInMemorySize(1048576);
    multipartResolver.setDefaultEncoding("UTF-8");
    return multipartResolver;
}

webflow配置

@Configuration
public class WebFlowConfig extends AbstractFlowConfiguration {

    @Autowired
    TilesViewResolver viewResolver;

    @Bean
    public FlowDefinitionRegistry flowRegistry() {
        return getFlowDefinitionRegistryBuilder()
            .setFlowBuilderServices(flowBuilderServices())
            .setBasePath("/WEB-INF/flows/")
            .addFlowLocation("signup.xml", UrlMap.SIGNUP_WEBFLOW)
            .addFlowLocation("user-edit.xml", UrlMap.PROFILE_EDIT_WEBFLOW)
            .build();
    }

    @Bean
    public FlowExecutor flowExecutor() {
        return getFlowExecutorBuilder(flowRegistry()).build();
    }

    @Bean
    public FlowHandlerAdapter flowHandlerAdapter() {
        final FlowHandlerAdapter flowHandlerAdapter = new FlowHandlerAdapter();
        flowHandlerAdapter.setFlowExecutor(flowExecutor());
        return flowHandlerAdapter;
    }

    @Bean
    public FlowHandlerMapping flowHandlerMapping() {
        final FlowHandlerMapping flowHandlerMapping = new FlowHandlerMapping();
        flowHandlerMapping.setFlowRegistry(flowRegistry());
        // this has to be less than -1
        flowHandlerMapping.setOrder(-2);
        return flowHandlerMapping;
    }

    @Bean
    public MvcViewFactoryCreator mvcViewFactoryCreator() {
        final MvcViewFactoryCreator mvcViewFactoryCreator = new MvcViewFactoryCreator();
        final List<ViewResolver> viewResolvers = Collections.singletonList(viewResolver);
        mvcViewFactoryCreator.setViewResolvers(viewResolvers);
        return mvcViewFactoryCreator;
    }

    @Bean
    public FlowBuilderServices flowBuilderServices() {
        return getFlowBuilderServicesBuilder().setViewFactoryCreator(mvcViewFactoryCreator())
            .setValidator(localValidatorFactoryBean()).build();
    }

    @Bean
    public LocalValidatorFactoryBean localValidatorFactoryBean() {
        return new LocalValidatorFactoryBean();
    }
}

在Tomcat的context.xml中，我已经添加了AllowCasualMultiPartParsing=“true”

在requestParameters对象中只有3个对象：

• 执行
• _eventid_forward
• _CSRF

日志中有一些相关行

DEBUG 2015-03-13 18:03:15,053: org.springframework.web.multipart.support.MultipartFilter - Using MultipartResolver 'filterMultipartResolver' for MultipartFilter
DEBUG 2015-03-13 18:03:15,053: org.springframework.beans.factory.support.DefaultListableBeanFactory - Returning cached instance of singleton bean 'filterMultipartResolver'
DEBUG 2015-03-13 18:03:15,053: org.springframework.web.multipart.support.MultipartFilter - Resolving multipart request [/registrazione] with MultipartFilter
DEBUG 2015-03-13 18:03:15,060: org.springframework.web.multipart.commons.CommonsMultipartResolver - Found multipart file [multipartFileUpload] of size 469217 bytes with original filename [PoliziaMunicipale.png], stored in memory
....
DEBUG 2015-03-13 18:03:15,072: org.springframework.binding.mapping.impl.DefaultMapper - Beginning mapping between source [org.springframework.webflow.core.collection.LocalParameterMap] and target [it.openex.pmcommonw.form.FileForm]
DEBUG 2015-03-13 18:03:15,072: org.springframework.binding.mapping.impl.DefaultMapping - Adding mapping result [TargetAccessError@34bc31ea mapping = parameter:'execution' -> execution, code = 'propertyNotFound', error = true, errorCause = org.springframework.binding.expression.PropertyNotFoundException: Property not found, originalValue = 'e1s2', mappedValue = [null]]
DEBUG 2015-03-13 18:03:15,072: org.springframework.binding.mapping.impl.DefaultMapper - Completing mapping between source [org.springframework.webflow.core.collection.LocalParameterMap] and target [it.openex.pmcommonw.form.FileForm]; total mappings = 1; total errors = 1

我不确定它是否有用，但在org.springframework.webflow.context.servlet.HttpServletRequestParameterMap第52行

if (request instanceof MultipartHttpServletRequest) {
        // ... process multipart data
    }

检查失败，因为请求是org.springframework.security.web.context.httpsessionsecuritycontextrepository$servlet3SaveTosessionRequestWrapper的实例

我可以确认MultiPartRequest.getFile（“文件”）也起作用。

但是，我无法启用org.springframework.web.multipart.support.multipartfilter筛选器。

如果启用了它，multipartRequest是StandardMultiPartTtpServletRequest的一个实例，它包含一个Servlet3SecurityContextHolderAwarerRequestWrapper，包装一个Servlet3SaveTosessionRequestWrapper，最后包含一个无法访问的DefaultMultiPartTtpServletRequest和我需要的multipartFile。

如果禁用它，我可以获得它，因为multipartRequest成为DefaultMultipartTtpServletRequest的实例，但没有文件验证，也没有遵守CommonsMultipartResolver的maxUploadSize限制。

此外，如果Tomcat由于文件太大而启动异常，超出了Tomcat的maxPostSize限制，则该异常将被我的CustomAccessDeniedHandler捕获，因为其类型为org.SpringFramework.Security.Access.AccessDeniedException，并且错误消息为在请求参数“_CSRF”或头“x-csrf-token”上找到无效的CSRF令牌“null”。。

查看request对象，我可以看到原始的Tomcat异常org.apache.Tomcat.util.html" target="_blank">http.FileUpload.FileUploadBase$SizeLimitExcededException。似乎没有什么可以正确地处理它，但是，正如我所说的，如果我启用MultipartFilter，我就无法获取文件。

Answer 1

我们遇到了同样的问题，因为我们在web应用程序中使用了Spring Security4.xx。问题是org.springframework.security.web.context.httpsessionsecuritycontextropitory$servlet3SaveTosessionRequestWrapper不是org.springframework.web.multipart.multipartttpservletrequest的实例，但它包含一个实例。转换为将不起作用，将发生ClassCastException。

这就是为什么

if (request instanceof MultipartHttpServletRequest) {
    // ... process multipart data
}

永远不能是true。

其想法是从本机httpservletrequest创建org.springframework.web.multipart.support.StandardMultiparthttpservletrequest，它可以工作。

在我们的WebApp中，我们使用Spring Webflow文档第6.5.1节中指出的Pojo操作。调用POJO操作。

我们的解决办法：

PojoAction.java

public String fileUpload(RequestContext requestContext) {
    final ServletExternalContext context = (ServletExternalContext) requestContext.getExternalContext();
    final MultipartHttpServletRequest multipartRequest = new StandardMultipartHttpServletRequest((HttpServletRequest)context.getNativeRequest());
    final File file = multipartRequest.getFile("file");
    fileUploadHandler.processFile(file); //do something with the submitted file
}

在flow.xml中，我们有一个动作状态，如下所示：

<action-state id="upload-action">
    <evaluate expression="pojoAction.uploadFile(flowRequestContext)"/>
    <transition to="show"/>
</action-state>

    <filter>
        <filter-name>csrfFilter</filter-name>
        <filter-class>
            org.springframework.web.filter.DelegatingFilterProxy
        </filter-class>
        <async-supported>true</async-supported>
    </filter>
    <filter-mapping>
        <filter-name>csrfFilter</filter-name>
        <url-pattern>/*</url-pattern>
     </filter-mapping>

     <filter>
        <filter-name>springSecurityFilterChain</filter-name>
        <filter-class>
           org.springframework.web.filter.DelegatingFilterProxy
        </filter-class>
      </filter>
      <filter-mapping>
         <filter-name>springSecurityFilterChain</filter-name>
         <url-pattern>/*</url-pattern>
         <dispatcher>REQUEST</dispatcher>
         <dispatcher>ERROR</dispatcher>
      </filter-mapping>