springboot2实现文件上传下载预览

本文使用springboot2，对文件的基础上传下载预览进行说明 直接上代码

依赖文件

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>demo5</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.7.5</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
            <version>2.7.5</version>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>7</source>
                    <target>7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

配置文件

# 设置最大上传大小
spring:
  servlet:
    multipart:
      max-file-size: 100MB

# 设置上传路径
upload:
  folder: D:/file/
  download: /download?fileName=

返回结果

package com.fileExample.pojo;

public class Result {

    private String status;
    private Object msg;
    private Object url;

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public Object getMsg() {
        return msg;
    }

    public void setMsg(Object msg) {
        this.msg = msg;
    }

    public Object getUrl() {
        return url;
    }

    public void setUrl(Object url) {
        this.url = url;
    }
}

文件相关操作

package com.fileExample.controller;

import com.fileExample.pojo.Result;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.*;

@RestController
public class FileController {

    @Value("${upload.folder}")
    private String root;

    @Value("${upload.download}")
    private String download;

    /**
     * 文件上传
     * @param file
     * @param request
     * @return
     */
    @PostMapping("/upload")
    public Result fileUpload(MultipartFile file, HttpServletRequest request) {
        Result result = new Result();
        // 获取文件名称
        String originalName = file.getOriginalFilename();

        // 判断存放目录是否存在，不存在则创建
        File folder = new File(root);
        if (!folder.exists()) {
            folder.mkdirs();
        }

        // 保存文件对象，uuid防止文件重名
        String newName = UUID.randomUUID() + originalName.substring(originalName.lastIndexOf("."));
        String strNewFileName = UUID.randomUUID().toString().replaceAll("-", "") + newName;
        try {
            // 上传文件
            // 如果需要上传数据库可以在此处稍作处理
            file.transferTo(new File(folder, strNewFileName));
            // 将文件下载地址或预览地址直接返回给前端，前端可以直接将文件进行预览
            String url = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + download + strNewFileName;
            result.setStatus("200");
            result.setUrl(url);
        } catch (IOException e) {
            e.printStackTrace();
            result.setStatus("500");
            result.setMsg(e.getMessage());
        }
        return result;
    }

    /**
     * 文件下载
     * @param fileName
     * @param response
     */
    @GetMapping("/download")
    public void download(String fileName, HttpServletResponse response) {
        Path path = Paths.get(root + fileName);
        if (Files.exists(path)) {
            String fileSuffix = fileName.substring(fileName.lastIndexOf(".") + 1);
            // 设置响应头类型
            response.setContentType("application/" + fileSuffix);
            try {
                // 设置响应头
                response.addHeader("Content-Disposition", "attachment;filename=" + new String(fileName.getBytes("UTF-8"), "ISO8859-1"));
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                // 下载文件
                Files.copy(path, response.getOutputStream());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 文件预览
     * @param fileName
     * @param response
     */
    @GetMapping("/preview")
    public void preview(String fileName, HttpServletResponse response) {
        Path path = Paths.get(root + fileName);
        if (Files.exists(path)) {
            String fileSuffix = fileName.substring(fileName.lastIndexOf(".") + 1);

            // 根据文件类型设置合适的响应内容类型
            if (fileSuffix.equalsIgnoreCase("jpg") || fileSuffix.equalsIgnoreCase("jpeg") || fileSuffix.equalsIgnoreCase("png") || fileSuffix.equalsIgnoreCase("gif")) {
                response.setContentType("image/" + fileSuffix);
            } else {
                // 对于其他文件类型，可以根据需要设置不同的内容类型
                // 或者生成预览内容，返回预览页面等
                // 这里对于其他类型直接进行下载
                response.setContentType("application/" + fileSuffix);
                try {
                    response.addHeader("Content-Disposition", "attachment;filename=" + new String(fileName.getBytes("UTF-8"), "ISO8859-1"));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            try {
                Files.copy(path, response.getOutputStream());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

}