文件的上传下载

package com.example.file.controller;

import com.example.file.utils.FileUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.Resource;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;

@RestController
@RequestMapping("/file")
public class FileController {

    @Autowired
    private FileUtil fileUtil;

    @GetMapping("/spring/download")
    public ResponseEntity<Resource> download() throws Exception {
        String filePath = "D:\\1.jpg";
        String fileName = "Spring框架下载.jpg";
        return fileUtil.download(filePath,fileName);
    }

    @GetMapping("/io/download")
    public void ioDownload(HttpServletResponse response) throws Exception {
        String filePath = "D:\\1.jpg";
        String fileName = "IO下载.jpg";
        fileUtil.download(filePath,fileName,response);
    }

    @GetMapping("/tiny/download")
    public void tinyDownload(HttpServletResponse response) throws Exception {
        String filePath = "D:\\1.jpg";
        String fileName = "tiny下载.jpg";
        fileUtil.downloadTinyFile(filePath,fileName,response);
    }

    @PostMapping("/multipart/upload")
    public String download(MultipartFile file) throws Exception {
        String storagePath = "D:\\";
        return fileUtil.upload(file,storagePath);
    }
}

package com.example.file.utils;

import org.apache.tomcat.util.http.fileupload.IOUtils;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Component;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.util.UUID;

/**
 * 文件工具类
 * @author HTT
 */
@Component
public class FileUtil {

    /**
     * 使用Spring框架自带的下载方式
     * @param filePath
     * @param fileName
     * @return
     */
    public ResponseEntity<Resource> download(String filePath,String fileName) throws Exception {
        fileName = URLEncoder.encode(fileName,"UTF-8");
        File file = new File(filePath);
        if(!file.exists()){
            throw new Exception("文件不存在");
        }
        return ResponseEntity.ok().header(HttpHeaders.CONTENT_DISPOSITION,
                    "attachment; filename=" + fileName ).body(new FileSystemResource(filePath));
    }

    /**
     * 通过IOUtils以流的形式下载
     * @param filePath
     * @param fileName
     * @param response
     */
    public void download(String filePath , String fileName, HttpServletResponse response) throws Exception {
        fileName = URLEncoder.encode(fileName,"UTF-8");
        File file=new File(filePath);
        if(!file.exists()){
            throw new Exception("文件不存在");
        }
        response.setHeader("Content-disposition","attachment;filename="+ fileName);
        FileInputStream fileInputStream = new FileInputStream(file);
        IOUtils.copy(fileInputStream,response.getOutputStream());
        response.flushBuffer();
        fileInputStream.close();
    }

    /**
     * 原始的方法，下载一些小文件，边读边下载的
     * @param filePath
     * @param fileName
     * @param response
     * @throws Exception
     */
    public void downloadTinyFile(String filePath,String fileName, HttpServletResponse response)throws Exception{
        File file = new File(filePath);
        fileName = URLEncoder.encode(fileName, "UTF-8");
        if(!file.exists()){
            throw new Exception("文件不存在");
        }
        FileInputStream in = new FileInputStream(file);
        response.setHeader("Content-Disposition", "attachment;filename="+fileName);
        OutputStream out = response.getOutputStream();
        byte[] b = new byte[1024];
        int len = 0;
        while((len = in.read(b))!=-1){
            out.write(b, 0, len);
        }
        out.flush();
        out.close();
        in.close();
    }

    /**
     * 上传文件
     * @param multipartFile
     * @param storagePath
     * @return
     * @throws Exception
     */
    public String upload(MultipartFile multipartFile, String storagePath) throws Exception{
        if (multipartFile.isEmpty()) {
            throw new Exception("文件不能为空！");
        }
        String originalFilename = multipartFile.getOriginalFilename();
        String newFileName = UUID.randomUUID()+"_"+originalFilename;
        String filePath = storagePath+newFileName;
        File file = new File(filePath);
        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdirs();
        }
        multipartFile.transferTo(file);
        return filePath;
    }

}

package com.example.file.test;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;

public class DownLoadFile {
    /**
     * @param path     想要下载的文件的路径
     * @param response
     * @功能描述 下载文件:
     */
    @RequestMapping("/download")
    public void download(String path, HttpServletResponse response) throws FileNotFoundException {
        Logger log = LoggerFactory.getLogger(DownLoadFile.class);

        try {
            // path是指想要下载的文件的路径
            File file = new File(path);
            log.info(file.getPath());
            // 获取文件名
            String filename = file.getName();
            // 获取文件后缀名
            String ext = filename.substring(filename.lastIndexOf(".") + 1).toLowerCase();
            log.info("文件后缀名：" + ext);
            // 将文件写入输入流
            FileInputStream fileInputStream = new FileInputStream(file);
            InputStream fis = new BufferedInputStream(fileInputStream);
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            fis.close();

            // 清空response
            response.reset();
            // 设置response的Header
            response.setCharacterEncoding("UTF-8");
            //Content-Disposition的作用：告知浏览器以何种方式显示响应返回的文件，用浏览器打开还是以附件的形式下载到本地保存
            //attachment表示以附件方式下载   inline表示在线打开   "Content-Disposition: inline; filename=文件名.mp3"
            // filename表示文件的默认名称，因为网络传输只支持URL编码的相关支付，因此需要将文件名URL编码后进行传输,前端收到后需要反编码才能获取到真正的名称
            response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
            // 告知浏览器文件的大小
            response.addHeader("Content-Length", "" + file.length());
            OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
            response.setContentType("application/octet-stream");
            outputStream.write(buffer);
            outputStream.flush();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    /**

     * @param path     指想要下载的文件的路径

     * @param response

     * @功能描述 下载文件:将输入流中的数据循环写入到响应输出流中，而不是一次性读取到内存

     */

    @RequestMapping("/downloadLocal")

    public void downloadLocal(String path, HttpServletResponse response) throws IOException {

        // 读到流中
        InputStream inputStream = new FileInputStream(path);// 文件的存放路径
        response.reset();
        response.setContentType("application/octet-stream");
        String filename = new File(path).getName();
        response.addHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));
        ServletOutputStream outputStream = response.getOutputStream();
        byte[] b = new byte[1024];
        int len;
        //从输入流中读取一定数量的字节，并将其存储在缓冲区字节数组中，读到末尾返回-1
        while ((len = inputStream.read(b)) > 0) {
            outputStream.write(b, 0, len);
        }
        inputStream.close();

    }


    /**

     * @param path       下载后的文件路径和名称

     * @param netAddress 文件所在网络地址

     * @功能描述 网络文件下载到服务器本地

     */

    @RequestMapping("/netDownloadLocal")

    public void downloadNet(String netAddress, String path) throws IOException {

        URL url = new URL(netAddress);
        URLConnection conn = url.openConnection();
        InputStream inputStream = conn.getInputStream();
        FileOutputStream fileOutputStream = new FileOutputStream(path);
        int bytesum = 0;
        int byteread;
        byte[] buffer = new byte[1024];
        while ((byteread = inputStream.read(buffer)) != -1) {
            bytesum += byteread;
            System.out.println(bytesum);
            fileOutputStream.write(buffer, 0, byteread);
        }
        fileOutputStream.close();

    }

    /**
     * @param netAddress
     * @param filename
     * @param isOnLine
     * @param response
     * @功能描述 网络文件获取到服务器后，经服务器处理后响应给前端
     */
    @RequestMapping("/netDownLoadNet")
    public void netDownLoadNet(String netAddress, String filename, boolean isOnLine, HttpServletResponse response) throws Exception {
        URL url = new URL(netAddress);
        URLConnection conn = url.openConnection();
        InputStream inputStream = conn.getInputStream();
        response.reset();
        response.setContentType(conn.getContentType());
        if (isOnLine) {
            // 在线打开方式 文件名应该编码成UTF-8
            response.setHeader("Content-Disposition", "inline; filename=" + URLEncoder.encode(filename, "UTF-8"));
        } else {
            //纯下载方式 文件名应该编码成UTF-8
            response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));
        }

        byte[] buffer = new byte[1024];
        int len;
        OutputStream outputStream = response.getOutputStream();
        while ((len = inputStream.read(buffer)) > 0) {
            outputStream.write(buffer, 0, len);
        }
        inputStream.close();

    }


}