我正在尝试从部署在服务器上的 Rest Web 服务返回一个文件流，并从客户端上的 Rest Web 服务处理这个流。 在服务器上我使用这段代码:

@Override
@RequestMapping(value = "/file", method = RequestMethod.GET, produces = MediaType.APPLICATION_OCTET_STREAM_VALUE) 
public @ResponseBody Resource getAcquisition(@RequestParam(value="filePath", required = true) String filePath) throws FileNotFoundException{
    // acquiring the stream
    File file= new File(filePath);
    InputStream stream = new FileInputStream(file);
    // counting the length of data
    final long contentLength = file.length() ;

    return new InputStreamResource(stream){
        @Override
        public long contentLength() throws IOException {
            return contentLength;
        }
    };
}

目前，我在客户端上使用它(然后我必须在文件系统上写入文件)

@Override
public void getFile(String serverIp, String toStorePath, String filePath) throws Exception{
    RestTemplate restTemplate = new RestTemplate();
    Resource resource  = restTemplate.getForObject(serverIp + "ATS/client/file/?filePath={filePath}",Resource.class, filePath);
    File file=resource.getFile();
    System.out.println(file.length());
}

但是服务器返回这个异常:

ERROR com.controller.ErrorController - org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation
at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:195)
at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:100)
at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:166)
at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:80)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:127)
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.doGet(FrameworkServlet.java:861)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
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:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
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:142)
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:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1526)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1482)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$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)

即使没有 MediaType 我也尝试过，但它不起作用。我还发布了我的 Spring 配置:

package com.config.core;

import java.util.List;
import java.util.Properties;

import org.apache.commons.dbcp.BasicDataSource;
import org.hibernate.jpa.HibernatePersistenceProvider;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.thymeleaf.spring4.SpringTemplateEngine;
import org.thymeleaf.spring4.view.ThymeleafViewResolver;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.hibernate4.Hibernate4Module;


/**
 * All the configuration bean
 *
 */
@EnableWebMvc
@Configuration
@PropertySource(value = { "classpath:application.properties" })
@ComponentScan({ "com.*" })
@EnableTransactionManagement
@Import({ SpringMvcInitializer.class })
@EnableJpaRepositories("com.repository")
public class AppConfig extends WebMvcConfigurerAdapter{
    @Autowired
    private Environment env;

    private static final String PROPERTY_NAME_DATABASE_DRIVER = "db.driver";
    private static final String PROPERTY_NAME_DATABASE_PASSWORD = "db.password";
    private static final String PROPERTY_NAME_DATABASE_URL = "db.url";
    private static final String PROPERTY_NAME_DATABASE_USERNAME = "db.username";

    private static final String PROPERTY_NAME_HIBERNATE_DIALECT = "hibernate.dialect";
//  private static final String PROPERTY_NAME_HIBERNATE_SHOW_SQL = "hibernate.show_sql";
    private static final String PROPERTY_NAME_ENTITYMANAGER_PACKAGES_TO_SCAN = "entitymanager.packages.to.scan";
    private static final String PROPERTY_NAME_HIBERNATE_FORMAT_SQL = "hibernate.format_sql";


/**
 * li utilizzavo prima quando facevo l'autenticazione, vedere come fare ora che ho messo nelle proprietà il percorso com.domain
 * @return
 */
//  @Bean
//  public SessionFactory sessionFactory() {
//      LocalSessionFactoryBuilder builder = new LocalSessionFactoryBuilder(dataSource());
//      builder
//      .scanPackages(env.getRequiredProperty(PROPERTY_NAME_ENTITYMANAGER_PACKAGES_TO_SCAN))
//      .addProperties(getHibernateProperties());
//
//      return builder.buildSessionFactory();
//  }
//  @Bean
//  public HibernateTransactionManager txManager() {
//      return new HibernateTransactionManager(sessionFactory());
//  }

    /**
     * This and the next methods are used to avoid exception while jackson mapping the entity, so fields are setted with null value
     * unless use Hibernate.initialize
     * @return
     */
    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);
    }

    private Properties getHibernateProperties() {
        Properties properties = new Properties();
        properties.put(PROPERTY_NAME_HIBERNATE_DIALECT, env.getRequiredProperty(PROPERTY_NAME_HIBERNATE_DIALECT));
//      properties.put(PROPERTY_NAME_HIBERNATE_SHOW_SQL, env.getRequiredProperty(PROPERTY_NAME_HIBERNATE_SHOW_SQL));
        properties.put(PROPERTY_NAME_HIBERNATE_FORMAT_SQL, env.getRequiredProperty(PROPERTY_NAME_HIBERNATE_FORMAT_SQL));
        properties.put("hibernate.enable_lazy_load_no_trans",true);
        return properties;
    }

    @Bean(name = "dataSource")
    public BasicDataSource dataSource() {
        BasicDataSource ds = new BasicDataSource();
        ds.setDriverClassName(env.getRequiredProperty(PROPERTY_NAME_DATABASE_DRIVER));
        ds.setUrl(env.getRequiredProperty(PROPERTY_NAME_DATABASE_URL));
        ds.setUsername(env.getRequiredProperty(PROPERTY_NAME_DATABASE_USERNAME));
        ds.setPassword(env.getRequiredProperty(PROPERTY_NAME_DATABASE_PASSWORD));
        return ds;
    }

    @Bean
    public ServletContextTemplateResolver TemplateResolver(){
        ServletContextTemplateResolver resolver = new ServletContextTemplateResolver();
        resolver.setPrefix("/WEB-INF/templates/pages/");
        resolver.setSuffix(".html");
        resolver.setTemplateMode("LEGACYHTML5");
        resolver.setCacheable(false);
        return resolver;
        /*ServletContextTemplateResolver resolver = new ServletContextTemplateResolver();
        resolver.setPrefix("/WEB-INF/pages/");
        resolver.setSuffix(".html");
        resolver.setTemplateMode("HTML5");
        return resolver;*/
    }

    @Bean
    public SpringTemplateEngine templateEngine(){
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(TemplateResolver());
        return templateEngine;
    }


    @Bean
    public ThymeleafViewResolver viewResolver() {
        ThymeleafViewResolver resolver = new ThymeleafViewResolver();
        resolver.setTemplateEngine(templateEngine());
        resolver.setOrder(1);
        resolver.setViewNames(new String[]{"*", "js/*", "template/*"});
        return resolver;
    }

    /**
     * Register multipartResolver for file upload
     * @return
     */
    @Bean
    public CommonsMultipartResolver multipartResolver() {
        CommonsMultipartResolver resolver=new CommonsMultipartResolver();
        resolver.setDefaultEncoding("utf-8");
        return resolver;    
    }

    /**
     * Allow use of bootstrap
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
            registry.addResourceHandler("/static/**")
                    .addResourceLocations("/static/");
    }

    /**
     * Allow use of JPA
     */
    @Bean
    public JpaTransactionManager transactionManager() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory().getObject());
        return transactionManager;
    }
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource());
        entityManagerFactoryBean.setPersistenceProviderClass(HibernatePersistenceProvider.class);
        entityManagerFactoryBean.setPackagesToScan(env.
        getRequiredProperty(PROPERTY_NAME_ENTITYMANAGER_PACKAGES_TO_SCAN));
        entityManagerFactoryBean.setJpaProperties(getHibernateProperties());
        return entityManagerFactoryBean;

    }
}

你知道这个问题吗？谢谢

更新:

@Override
@RequestMapping(value = "/file", method = RequestMethod.GET) 
public ResponseEntity<Resource> getAcquisition(HttpServletResponse resp,@RequestParam(value="filePath", required = true) String filePath) throws FileNotFoundException{
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.TEXT_PLAIN);
    resp.setContentType("application/octet-stream");
    File file= new File(filePath);
    InputStream stream = new FileInputStream(file);
    InputStreamResource inputStreamResource = new InputStreamResource(stream);
    return new ResponseEntity<Resource>(inputStreamResource, null, HttpStatus.OK);
}

但收到

Could not write content: No serializer found for class java.io.FileDescriptor

最佳答案

我是这样解决问题的

@Bean
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
    MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();

    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.registerModule(new Hibernate4Module());
    objectMapper.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);
    objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

    messageConverter.setObjectMapper(objectMapper);
    return messageConverter;
}


@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    converters.add(mappingJackson2HttpMessageConverter());
    converters.add(new ResourceHttpMessageConverter());
    super.configureMessageConverters(converters);
}

我在转换器列表中添加了一个 ResourceHttpMessageConverter。

这是资源:

@RequestMapping(value="/file/{uniqueKey}", method = RequestMethod.GET)
@ResponseBody
public FileSystemResource getUserFile(HttpServletResponse response, @PathVariable String uniqueKey){

    Map<String, String> metadata = authService.getUserFileMetadataByUniqueKey(uniqueKey);

    final File file = new File(metadata.get("filePath"));
    response.setContentType(metadata.get("contentType"));
    response.setHeader("Content-Disposition", "attachment; filename="+metadata.get("fileUniqueName"));

    return new FileSystemResource(file);
}

关于java - Spring Rest Web 服务将文件作为资源返回，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34182523/