SpringBoot文件上传下载和多文件上传（图文详解）

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最近在学习SpringBoot，以下是最近学习整理的实现文件上传下载的java代码：
1、开发环境：
IDEA15+ Maven+JDK1.8
2、新建一个maven工程：

3、工程框架

4、pom.xml文件依赖项

<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>SpringWebContent</groupId>
  <artifactId>SpringWebContent</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>SpringWebContent Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.3.RELEASE</version>
  </parent>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-devtools</artifactId>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <properties>
    <java.version>1.8</java.version>
  </properties>
  <build>
    <finalName>SpringWebContent</finalName>
  <plugins>
  <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
  </plugin>
</plugins>
  </build>
</project>

5、Application.java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {

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

6、FileController.java

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.List;

@Controller
public class FileController {
    @RequestMapping("/greeting")
    public String greeting(@RequestParam(value="name", required=false, defaultValue="World") String name, Model model) {
        model.addAttribute("name", name);
        return "greeting";
    }
    private static final Logger logger = LoggerFactory.getLogger(FileController.class);
    //文件上传相关代码
    @RequestMapping(value = "upload")
    @ResponseBody
    public String upload(@RequestParam("test") MultipartFile file) {
        if (file.isEmpty()) {
            return "文件为空";
        }
        // 获取文件名
        String fileName = file.getOriginalFilename();
        logger.info("上传的文件名为：" + fileName);
        // 获取文件的后缀名
        String suffixName = fileName.substring(fileName.lastIndexOf("."));
        logger.info("上传的后缀名为：" + suffixName);
        // 文件上传后的路径
        String filePath = "E://test//";
        // 解决中文问题，liunx下中文路径，图片显示问题
        // fileName = UUID.randomUUID() + suffixName;
        File dest = new File(filePath + fileName);
        // 检测是否存在目录
        if (!dest.getParentFile().exists()) {
            dest.getParentFile().mkdirs();
        }
        try {
            file.transferTo(dest);
            return "上传成功";
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "上传失败";
    }

    //文件下载相关代码
    @RequestMapping("/download")
    public String downloadFile(org.apache.catalina.servlet4preview.http.HttpServletRequest request, HttpServletResponse response){
        String fileName = "FileUploadTests.java";
        if (fileName != null) {
            //当前是从该工程的WEB-INF//File//下获取文件(该目录可以在下面一行代码配置)然后下载到C:\\users\\downloads即本机的默认下载的目录
            String realPath = request.getServletContext().getRealPath(
                    "//WEB-INF//");
            File file = new File(realPath, fileName);
            if (file.exists()) {
                response.setContentType("application/force-download");// 设置强制下载不打开
                response.addHeader("Content-Disposition",
                        "attachment;fileName=" +  fileName);// 设置文件名
                byte[] buffer = new byte[1024];
                FileInputStream fis = null;
                BufferedInputStream bis = null;
                try {
                    fis = new FileInputStream(file);
                    bis = new BufferedInputStream(fis);
                    OutputStream os = response.getOutputStream();
                    int i = bis.read(buffer);
                    while (i != -1) {
                        os.write(buffer, 0, i);
                        i = bis.read(buffer);
                    }
                    System.out.println("success");
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if (bis != null) {
                        try {
                            bis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fis != null) {
                        try {
                            fis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
        return null;
    }
    //多文件上传
    @RequestMapping(value = "/batch/upload", method = RequestMethod.POST)
    @ResponseBody
    public String handleFileUpload(HttpServletRequest request) {
        List<MultipartFile> files = ((MultipartHttpServletRequest) request)
                .getFiles("file");
        MultipartFile file = null;
        BufferedOutputStream stream = null;
        for (int i = 0; i < files.size(); ++i) {
            file = files.get(i);
            if (!file.isEmpty()) {
                try {
                    byte[] bytes = file.getBytes();
                    stream = new BufferedOutputStream(new FileOutputStream(
                            new File(file.getOriginalFilename())));
                    stream.write(bytes);
                    stream.close();

                } catch (Exception e) {
                    stream = null;
                    return "You failed to upload " + i + " => "
                            + e.getMessage();
                }
            } else {
                return "You failed to upload " + i
                        + " because the file was empty.";
            }
        }
        return "upload successful";
    }

7、index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Getting Started: Serving Web Content</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<p>Get your greeting <a href="/greeting">here</a></p>
<form action="/upload" method="POST" enctype="multipart/form-data">
    文件：<input type="file" name="test"/>
    <input type="submit" />
</form>
<a href="/download">下载test</a>
<p>多文件上传</p>
<form method="POST" enctype="multipart/form-data" action="/batch/upload">
    <p>文件1：<input type="file" name="file" /></p>
    <p>文件2：<input type="file" name="file" /></p>
    <p><input type="submit" value="上传" /></p>
</form>
</html>

本文代码参考Spring官网：https://spring.io/guides/gs/serving-web-content/
完整工程地址：http://download.youkuaiyun.com/detail/coding13/9739116

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