springboot中的mapper有什么作用（springboot中的注解）

目录

• multipartResolver上传文件配置
  • 1、gradle配置
  • 2、注册Bean
• SpringBoot MultipartResolver的坑
  • 解决方案

multipartResolver上传文件配置

1、gradle配置

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1 2	compile ('commons-io:commons-io:1.4') compile('commons-fileupload:commons-fileupload:1.2.1')

2、注册Bean

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@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

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@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

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

自定义文件解析对象

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

以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。

原文链接：https://blog.csdn.net/u011110968/article/details/82856736