Spring Boot文件上传示例

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spring boot
restful
spring
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本文介绍如何在Spring Boot Web应用程序中上传文件。

使用的工具：

Spring Boot 1.4.3.RELEASE
Spring 4.3.5.RELEASE
Thymeleaf
Maven 3
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。

<project 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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.yiibai</groupId>
    <artifactId>spring-boot-file-upload</artifactId>
    <packaging>jar</packaging>
    <version>1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.3.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <!-- hot swapping, disable cache for template, enable live reload -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <!-- Package as an executable jar/war -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

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 -

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<body>

<h1>Spring Boot文件上传示例</h1>

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

</body>
</html>

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

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<body>

<h1>Spring Boot文件上传状态</h1>

<div th:if="${message}">
    <h2 th:text="${message}"/>
</div>

</body>
</html>

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 -

本站代码下载：http://www.yiibai.com/siteinfo/download.html

http://www.yiibai.com/spring-boot/file-upload.html

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Spring Boot文件上传示例（Ajax和REST） | jQuery - ajax

2017-06-18 14:14
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