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Spring boot MultipartResolver

【参考文章】：Required MultipartFile parameter 'file' is not present

【参考文章】：Springboot2.0 中 WebMvcConfigurerAdapter 过时问题处理

【参考文章】：spring boot EnableAutoConfiguration exclude 无效

实现了 MultipartResolver 常用接口有两个：

　　一个是  CommonsMultipartResolver：使用 Jakarta Commons FileUpload 解析 multipart 请求；

　　一个是 StandardServletMultipartResolver：依赖于 Servlet 3.0 解析 multipart 请求；

1. StandardServletMultipartResolver 

　　Spring boot 默认使用 StandardServletMultipartResolver 解析 multipart 请求；

@Configuration
@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class,
        MultipartConfigElement.class })
@ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)
@ConditionalOnWebApplication(type = Type.SERVLET)
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartAutoConfiguration {

</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">final</span><span style="color: rgba(0, 0, 0, 1)"> MultipartProperties multipartProperties;

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> MultipartAutoConfiguration(MultipartProperties multipartProperties) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.multipartProperties =<span style="color: rgba(0, 0, 0, 1)"> multipartProperties;
}

@Bean
@ConditionalOnMissingBean({ MultipartConfigElement.</span><span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">,
        CommonsMultipartResolver.</span><span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)"> })
</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> MultipartConfigElement multipartConfigElement() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">this</span><span style="color: rgba(0, 0, 0, 1)">.multipartProperties.createMultipartConfig();
}

@Bean(name </span>=<span style="color: rgba(0, 0, 0, 1)"> DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
@ConditionalOnMissingBean(MultipartResolver.</span><span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> StandardServletMultipartResolver multipartResolver() {
    StandardServletMultipartResolver multipartResolver </span>= <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> StandardServletMultipartResolver();
    multipartResolver.setResolveLazily(</span><span style="color: rgba(0, 0, 255, 1)">this</span><span style="color: rgba(0, 0, 0, 1)">.multipartProperties.isResolveLazily());
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> multipartResolver;
}



}

2. CommonsMultipartResolver

2.1 排除默认配置

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

2.2 添加 CommonsMultipartResolver 的依赖

         <!--文件上传-->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>

2.3 创建文件解析对象

@Slf4j
@Configuration
public class  WebMvcConfig implements WebMvcConfigurer {

<span style="color: rgba(255, 0, 0, 1)">@Bean(name </span></span><span style="color: rgba(255, 0, 0, 1)">= "multipartResolver")
</span><span style="color: rgba(0, 0, 255, 1)">public </span><span style="color: rgba(0, 0, 0, 1)">MultipartResolver multipartResolver() {
    log.info(</span>"Loading the multipart resolver"<span style="color: rgba(0, 0, 0, 1)">);
    CommonsMultipartResolver multipartResolver </span>= <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> CommonsMultipartResolver();
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> multipartResolver;
}



}