SpringBoot中的multipartResolver上传文件配置

时间：2022-03-26 09:02:16|栏目：JAVA代码|点击：次

multipartResolver上传文件配置

1、gradle配置

    compile ('commons-io:commons-io:1.4')
    compile('commons-fileupload:commons-fileupload:1.2.1')

2、注册Bean

    @Bean(name = "multipartResolver")
    public MultipartResolver multipartResolver(){
        CommonsMultipartResolver resolver = new CommonsMultipartResolver();
        resolver.setDefaultEncoding("UTF-8");
        //resolveLazily属性启用是为了推迟文件解析，以在在UploadAction中捕获文件大小异常
        resolver.setResolveLazily(true);
        resolver.setMaxInMemorySize(40960);
        //上传文件大小 50M 50*1024*1024
        resolver.setMaxUploadSize(50*1024*1024);
        return resolver;
    }

SpringBoot MultipartResolver的坑

在使用springBoot上传文件的时候，我们会用到MultipartResolver。我看通过源码可以看到

@Configuration
@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class,
  MultipartConfigElement.class })
@ConditionalOnProperty(prefix = "spring.http.multipart", name = "enabled", matchIfMissing = true)
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartAutoConfiguration {
 private final MultipartProperties multipartProperties;
 public MultipartAutoConfiguration(MultipartProperties multipartProperties) {
  this.multipartProperties = multipartProperties;
 }
 @Bean
 @ConditionalOnMissingBean({ MultipartConfigElement.class,
   CommonsMultipartResolver.class })
 public MultipartConfigElement multipartConfigElement() {
  return this.multipartProperties.createMultipartConfig();
 }
 @Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
 @ConditionalOnMissingBean(MultipartResolver.class)
 public StandardServletMultipartResolver multipartResolver() {
  StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();
  multipartResolver.setResolveLazily(this.multipartProperties.isResolveLazily());
  return multipartResolver;
 }

可以看出MultipartAutoConfiguration配置类，默认加载的是StandardServletMultipartResolver。

然而，我们往往会在项目中加入commons-fileupload依赖，加载的是CommonsMultipartResolver。此时同时使用两个，会产生冲突。

解决方案

1、使用SpringBoot 默认的StandardServletMultipartResolver，不依赖commons-fileupload。

2、使用commons-fileupload的CommonsMultipartResolver，

排除默认

spring:
  autoconfigure:
    exclude: org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration

自定义文件解析对象

    @Bean(name = "multipartResolver")
    public MultipartResolver multipartResolver() {
        CommonsMultipartResolver resolver = new CommonsMultipartResolver();
        resolver.setDefaultEncoding("UTF-8");
        return resolver;
    }

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