SpringBoot文件上传示例

本文介绍如何在Spring Boot Web应用程序中上传文件。

使用的工具 ：

1. Spring Boot 1.4.3.RELEASE
2. Spring 4.3.5.RELEASE
3. Thymeleaf
4. Maven 3
5. Embedded Tomcat 8.5.6

1. 项目结构

标准项目结构如下图所示 -

2. 项目依赖

Spring boot依赖关系，无需额外的文件上传库。

xmlns="http://maven.apache.org/POM/4.0.0"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
 http://maven.apache.org/maven-v4_0_0.xsd">
 >4.0.0>

 >com.yiibai>
 >spring-boot-file-upload>
 >jar>
 >1.0>

 >
 >org.springframework.boot>
 >spring-boot-starter-parent>
 >1.4.3.RELEASE>
 >

 >
 >1.8>
 >

 >

 >
 >org.springframework.boot>
 >spring-boot-starter-thymeleaf>
 >

 
 >
 >org.springframework.boot>
 >spring-boot-devtools>
 >true>
 >

 >

 >
 >
 
 >
 >org.springframework.boot>
 >spring-boot-maven-plugin>
 >
 >
 >

>

3.文件上传示例

Spring Boot文件上传，不需要什么特别的配置。在Controller中，将上传的文件映射到MultipartFile。
文件：UploadController.java -

package com.yiibai.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@Controller
public class UploadController {

 //Save the uploaded file to this folder
 private static String UPLOADED_FOLDER = "D://temp//";

 @GetMapping("/")
 public String index() {
 return "upload";
 }

 @PostMapping("/upload") // //new annotation since 4.3
 public String singleFileUpload(@RequestParam("file") MultipartFile file,
 RedirectAttributes redirectAttributes) {

 if (file.isEmpty()) {
 redirectAttributes.addFlashAttribute("message", "Please select a file to upload");
 return "redirect:uploadStatus";
 }

 try {

 // Get the file and save it somewhere
 byte[] bytes = file.getBytes();
 Path path = Paths.get(UPLOADED_FOLDER + file.getOriginalFilename());
 Files.write(path, bytes);

 redirectAttributes.addFlashAttribute("message",
 "You successfully uploaded '" + file.getOriginalFilename() + "'");

 } catch (IOException e) {
 e.printStackTrace();
 }

 return "redirect:/uploadStatus";
 }

 @GetMapping("/uploadStatus")
 public String uploadStatus() {
 return "uploadStatus";
 }

}

在thymeleaf，只是一些普通的HTML文件标签。文件：upload.html -

xmlns:th="http://www.thymeleaf.org">
>

>Spring Boot文件上传示例>

method="POST" action="/upload" enctype="multipart/form-data">
 type="file" name="file" />/>/>
 type="submit" value="提交" />
>

>
>

另外一个页面，用为显示文件上传的状态。文件：uploadStatus.html -

lang="en" xmlns:th="http://www.thymeleaf.org">
>

>Spring Boot文件上传状态>

th:if="${message}">
 
th:text="${message}"/>
>

>
>

4. 超过最大上传大小

要处理最大上传大小超出异常，请声明一个@ControllerAdvice并捕获MultipartException。
文件：GlobalExceptionHandler.java

package com.yiibai.controller;

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

@ControllerAdvice
public class GlobalExceptionHandler {

 //http://jira.spring.io/browse/SPR-14651
 //4.3.5 supports RedirectAttributes redirectAttributes
 @ExceptionHandler(MultipartException.class)
 public String handleError1(MultipartException e, RedirectAttributes redirectAttributes) {

 redirectAttributes.addFlashAttribute("message", e.getCause().getMessage());
 return "redirect:/uploadStatus";

 }

}

5. Tomcat连接重置

如果部署到Tomcat，请配置maxSwallowSize以避免此Tomcat连接重置问题。 对于嵌入式Tomcat，声明一个TomcatEmbeddedServletContainerFactory，如下所示, SpringBootWebApplication.java -

package com.yiibai;

import org.apache.coyote.http11.AbstractHttp11Protocol;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.embedded.tomcat.TomcatConnectorCustomizer;
import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
import org.springframework.context.annotation.Bean;

//http://www.agilegroup.co.jp/technote/springboot-fileupload-error-handling.html
@SpringBootApplication
public class SpringBootWebApplication {

 private int maxUploadSizeInMb = 10 * 1024 * 1024; // 10 MB

 public static void main(String[] args) throws Exception {
 SpringApplication.run(SpringBootWebApplication.class, args);
 }

 //Tomcat large file upload connection reset

 @Bean
 public TomcatEmbeddedServletContainerFactory tomcatEmbedded() {

 TomcatEmbeddedServletContainerFactory tomcat = new TomcatEmbeddedServletContainerFactory();

 tomcat.addConnectorCustomizers((TomcatConnectorCustomizer) connector -> {
 if ((connector.getProtocolHandler() instanceof AbstractHttp11Protocol<?>)) {
 //-1 means unlimited
 ((AbstractHttp11Protocol<?>) connector.getProtocolHandler()).setMaxSwallowSize(-1);
 }
 });

 return tomcat;

 }

}

6. Multipart文件大小

默认情况下，Spring Boot max文件上传大小为1MB，可以通过以下应用程序属性来配置它的值，application.properties -

#http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#common-application-properties
#search multipart
spring.http.multipart.max-file-size=10MB
spring.http.multipart.max-request-size=10MB

7. 运行示例

使用默认的嵌入式Tomcat启动Spring Boot的命令如下： mvn spring-boot:run ，运行结果如下 -

23:40:03,238 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@5a39699c - Registering current configuration as safe fallback point


 . ____ _ __ _ _
 /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/ ___)| |_)| | | | | || (_| | ) ) ) )
 ' |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
::Spring Boot:: (v1.4.3.RELEASE)

2017-03-30 23:40:04 INFO com.yiibai.SpringBootWebApplication - Starting SpringBootWebApplication on MY-PC with PID 880 (F:\worksp\springboot\file-upload\target\classes started by Administrator in F:\worksp\springboot\file-upload)
2017-03-30 23:40:04 DEBUG com.yiibai.SpringBootWebApplication - Running with Spring Boot v1.4.3.RELEASE, Spring v4.3.5.RELEASE
2017-03-30 23:40:04 INFO com.yiibai.SpringBootWebApplication - No active profile set, falling back to default profiles: default
2017-03-30 23:40:08 INFO com.yiibai.SpringBootWebApplication - Started SpringBootWebApplication in 5.359 seconds (JVM running for 6.355)

打开浏览器，访问： http://localhost:8080/ 输出结果如下 -

选择一个文件并将其上传，选择大于10mb的文件，将会看到页面提示如下 -