java - Spring MVC Fileupload - 如何在基于 XML 的应用程序中设置 MultipartConfigElement？

Question

我正在开发 Spring MVC + JPA + Fileupload XML based application 通过引用 http://websystique.com/springmvc/spring-mvc-4-fileupload-download-hibernate-example/ .这纯粹是一个基于注释的应用程序，在我的项目中我们使用基于 XML 的配置。到目前为止，我已经能够成功开发应用程序，其中一半工作正常。我唯一待处理的部分是下面的部分。我不确定在 applicationcontext.xml 或 web.mxl 文件中如何/在哪里配置它。

private MultipartConfigElement getMultipartConfigElement(){
        MultipartConfigElement multipartConfigElement = new MultipartConfigElement(LOCATION, MAX_FILE_SIZE, MAX_REQUEST_SIZE, FILE_SIZE_THRESHOLD);
        return multipartConfigElement;
    }
@Override
    protected void customizeRegistration(ServletRegistration.Dynamic registration) {
        registration.setMultipartConfig(getMultipartConfigElement());
    }
private static final String LOCATION = "C:/mytemp/";
    private static final long MAX_FILE_SIZE = 1024 * 1024 * 25;//25MB
    private static final long MAX_REQUEST_SIZE = 1024 * 1024 * 30;//30MB
    private static final int FILE_SIZE_THRESHOLD = 0;

原文件为:HelloWorldInitializer.java

public class HelloWorldInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    /*Set these variables for your project needs*/ 

    private static final String LOCATION = "C:/mytemp/";
    private static final long MAX_FILE_SIZE = 1024 * 1024 * 25;//25MB
    private static final long MAX_REQUEST_SIZE = 1024 * 1024 * 30;//30MB
    private static final int FILE_SIZE_THRESHOLD = 0;

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] { HelloWorldConfiguration.class };
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return null;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

    @Override
    protected void customizeRegistration(ServletRegistration.Dynamic registration) {
        registration.setMultipartConfig(getMultipartConfigElement());
    }

    private MultipartConfigElement getMultipartConfigElement(){
        MultipartConfigElement multipartConfigElement = new MultipartConfigElement(LOCATION, MAX_FILE_SIZE, MAX_REQUEST_SIZE, FILE_SIZE_THRESHOLD);
        return multipartConfigElement;
    }
}

HelloWorldConfiguration.java

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.websystique.springmvc")
public class HelloWorldConfiguration extends WebMvcConfigurerAdapter{

    @Bean(name="multipartResolver")
    public StandardServletMultipartResolver resolver(){
        return new StandardServletMultipartResolver();
    }

    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setViewClass(JstlView.class);
        viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");

        registry.viewResolver(viewResolver);
    }


    // Configure ResourceHandlers to serve static resources like CSS/ Javascript etc...
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("/static/");
    }

    //Configure MessageSource to lookup any validation/error message in internationalized property files
    @Bean
    public MessageSource messageSource() {
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        messageSource.setBasename("messages");
        return messageSource;
    }

    /**Optional. It's only required when handling '.' in @PathVariables which otherwise ignore everything after last '.' in @PathVaidables argument.
     * It's a known bug in Spring [https://jira.spring.io/browse/SPR-6164], still present in Spring 4.1.7.
     * This is a workaround for this issue.
     */
    @Override
    public void configurePathMatch(PathMatchConfigurer matcher) {
        matcher.setUseRegisteredSuffixPatternMatch(true);
    }
}

HibernateConfiguration.java

Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages={"com.websystique.springmvc.repository"})
@ComponentScan({ "com.websystique.springmvc.configuration" })
@PropertySource(value = { "classpath:application.properties" })
public class HibernateConfiguration {

    @Bean
    LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, Environment environment) {
        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();

        // dataSource
        entityManagerFactoryBean.setDataSource(dataSource);

        // Hibernate JPA Vendor Adapter
        entityManagerFactoryBean.setJpaVendorAdapter(new HibernateJpaVendorAdapter());

        // package to scan
        entityManagerFactoryBean.setPackagesToScan("com.websystique.springmvc.model");

        // JPA Properties
        entityManagerFactoryBean.setJpaProperties(getProperties(environment));

        return entityManagerFactoryBean;
    }


    public Properties getProperties(Environment environment){
        Properties jpaProperties = new Properties();

        //Configures the used database dialect. This allows Hibernate to create SQL that is optimized for the used database.
        jpaProperties.put("hibernate.dialect", environment.getRequiredProperty("hibernate.dialect"));

        //Specifies the action that is invoked to the database when the Hibernate SessionFactory is created or closed.
        jpaProperties.put("hibernate.hbm2ddl.auto", environment.getRequiredProperty("hibernate.hbm2ddl.auto"));

        //If the value of this property is true, Hibernate writes all SQL
        jpaProperties.put("hibernate.show_sql", environment.getRequiredProperty("hibernate.show_sql"));

        //If the value of this property is true, Hibernate will format the SQL
        jpaProperties.put("hibernate.format_sql", environment.getRequiredProperty("hibernate.format_sql"));

        return jpaProperties;
    }


    @Bean
    public DataSource dataSource(Environment environment) {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(environment.getRequiredProperty("jdbc.driverClassName"));
        dataSource.setUrl(environment.getRequiredProperty("jdbc.url"));
        dataSource.setUsername(environment.getRequiredProperty("jdbc.username"));
        dataSource.setPassword(environment.getRequiredProperty("jdbc.password"));

        return dataSource;
    }

    @Bean
    @Autowired
    public JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory){
        JpaTransactionManager jpaTransactionManager = new JpaTransactionManager();
        jpaTransactionManager.setEntityManagerFactory(entityManagerFactory);
        return jpaTransactionManager;
    }
}

这些我把它映射到XML文件的所有配置:

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xmlns:repository="http://www.springframework.org/schema/data/repository"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/data/repository http://www.springframework.org/schema/data/repository/spring-repository-1.11.xsd">


    <!-- Enables the Spring MVC @Controller programming model -->
    <mvc:annotation-driven />
    <context:component-scan base-package="com.websystique.springmvc.controller" />

    <mvc:resources location="/static/" mapping="/static/**" />

    <!-- Load database.properties file -->
    <context:property-placeholder location="classpath:application.properties" />

    <!-- Enable JPA Repositories -->
    <jpa:repositories base-package="com.websystique.springmvc.repository" />

    <!-- Enable Transaction Manager -->
    <tx:annotation-driven transaction-manager="transactionManager" />

    <!-- Necessary to get the entity manager injected into the factory bean -->
    <beans:bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />


    <!-- ====== MYSQL DataSource ====== -->
    <beans:bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource" >
        <beans:property name="driverClassName" value="${jdbc.driverClassName}" />
        <beans:property name="url" value="${jdbc.url}" />
        <beans:property name="username" value="${jdbc.username}" />
        <beans:property name="password" value="${jdbc.password}" />
    </beans:bean>

    <!-- ====== Hibernate JPA Vendor Adaptor ======= -->
    <beans:bean id="jpaVendorAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
        <beans:property name="showSql" value="${hibernate.show_sql}"/>
        <beans:property name="generateDdl" value="true"/>
        <beans:property name="database" value="MYSQL"/>
    </beans:bean>


    <!-- Beans -->
    <beans:bean id="userDocumentService" class="com.websystique.springmvc.service.UserDocumentServiceImpl" />
    <beans:bean id="userService" class="com.websystique.springmvc.service.UserServiceImpl" />
    <beans:bean id="fileValidator" class="com.websystique.springmvc.util.FileValidator" />

    <!-- ======== Entity Manager factory ======== -->
    <beans:bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <!-- Data Source -->
        <beans:property name="dataSource" ref="dataSource"/>

        <!-- JPA Vendor Adaptor -->
        <beans:property name="jpaVendorAdapter" ref="jpaVendorAdapter"/>

        <!-- spring based scanning for entity classes-->
        <beans:property name="packagesToScan" value="com.websystique.springmvc.model" />

        <beans:property name="jpaProperties">
            <beans:props>
                <beans:prop key="hibernate.hbm2ddl.auto">update</beans:prop>  <!-- validate | update | create | create-drop -->
                <beans:prop key="hibernate.dialect">${hibernate.dialect}</beans:prop> 
                <!-- <beans:prop key="hibernate.cache.use_query_cache">true</beans:prop> --> 
            </beans:props>
        </beans:property>
    </beans:bean>

    <!-- ======== Transaction Manager ==== -->
    <beans:bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <beans:property name="entityManagerFactory" ref="entityManagerFactory" />
    </beans:bean>


    <!-- Localization of hibernate messages during validation!-->
    <beans:bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
        <beans:property name="basename" value="classpath:messages" />
        <beans:property name="defaultEncoding" value="UTF-8" />
    </beans:bean>

    <beans:bean name="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean"/>


    <!-- This is for JSP -->
    <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>
</beans:beans>

现在唯一需要实现的功能是 MultipartConfigElement。如何以及在哪里实现它？因为没有这个配置我

see the below error:
Jan 14, 2017 3:20:09 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [appServlet] in context with path [/spring-mvc-fileupload-xml] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException
    at com.websystique.springmvc.controller.AppController.saveDocument(AppController.java:199)
    at com.websystique.springmvc.controller.AppController.uploadDocument(AppController.java:189)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:111)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:806)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:729)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:509)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1104)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

Answer 1

除了提出的问题之外，简单的解决方案是添加以下依赖项:

<dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.3.1</version>
</dependency>

然后在 servlet-context.xml 文件中创建以下 bean。

<beans:bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />

完成!!!