1. 分片：按照自定义缓冲区大小，将大文件分成多个小文件片段。
2. 断点续传：根据分片数量，给每个小文件通过循环起对应名称，当文件下载中断在续传时，判断小文件名称若存在则不存了，此时还需要判断文件若不是最后一个分片则大小为缓冲区固定大小，若没达到则证明小文件没传完需要重新传输。
3. 合并：下载时通过线程池创建任务进行下载或上传、当判断最后一个分片传完时，调用合并方法，根据之前定义的文件名称顺序进行合并，肯能出现最后一个分片传完，之前分片未传完的情况，需要使用while循环进行判断，多文件未传输完，则等待一会继续判断。
4. 大文件秒传：实际上是根据文件名称区一个唯一的md5值存储，传文件时进行判断，若存在则不传。
# 配置服务端口
server:
port: 8018
spring:
servlet:
multipart:
# Spring Boot中有默认的文件上传组件，在使用ServletFileUpload时需要关闭Spring Boot的默认配置
enabled: false
# 设置单个文件大小
max-file-size: 1GB
# 设置单次请求文件的总大小
max-request-size: 10GB
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.1</version>
</dependency>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.4</version>
</dependency>
<!-- 做断点下载使用 -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpcore</artifactId>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.22</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version>
</dependency>
</dependencies>
业务逻辑代码
package com.liyh.service;
import com.liyh.entity.DownloadFileInfo;
import com.liyh.entity.FileInfo;
import com.liyh.entity.UploadFileInfo;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClients;
import org.springframework.stereotype.Service;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
@Service
public class FileService {
/**
* 编码
*/
private static final String UTF_8 = "UTF-8";
/**
* 文件上传路径(当前项目路径下，也可配置固定路径)
*/
private String uploadPath = System.getProperty("user.dir") + "/springboot-file/upload/";
/**
* 下载指定文件
*/
private String downloadFile = "D:\\Download\\git.exe";
/**
* 文件下载地址(当前项目路径下，也可配置固定路径)
*/
private String downloadPath = System.getProperty("user.dir") + "/springboot-file/download/";
/**
* 分片下载每一片大小为50M
*/
private static final Long PER_SLICE = 1024 * 1024 * 50L;
/**
* 定义分片下载线程池
*/
private ExecutorService executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
/**
* final string
*/
private static final String RANGE = "Range";
/**
* 上传文件
*/
public void upload(HttpServletRequest request, HttpServletResponse response) throws Exception {
// 获取ServletFileUpload
ServletFileUpload servletFileUpload = getServletFileUpload();
List<FileItem> items = servletFileUpload.parseRequest(request);
// 获取文件信息
UploadFileInfo uploadFileInfo = getFileInfo(items);
// 写入临时文件
writeTempFile(items, uploadFileInfo);
// 判断是否合并
mergeFile(uploadFileInfo);
// 返回结果
response.setCharacterEncoding(UTF_8);
response.getWriter().write("上传成功");
}
/**
* 获取ServletFileUpload
*/
private ServletFileUpload getServletFileUpload() {
// 设置缓冲区大小，先读到内存里在从内存写
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setSizeThreshold(1024);
File file = new File(uploadPath);
// 如果文件夹不存在则创建
if (!file.exists() && !file.isDirectory()) {
file.mkdirs();
}
factory.setRepository(file);
// 解析
ServletFileUpload upload = new ServletFileUpload(factory);
// 设置单个大小与最大大小
upload.setFileSizeMax(1 * 1024 * 1024 * 1024L);
upload.setSizeMax(10 * 1024 * 1024 * 1024L);
return upload;
}
/**
* 获取文件信息
*
* @param items
* @return
* @throws UnsupportedEncodingException
*/
private UploadFileInfo getFileInfo(List<FileItem> items) throws UnsupportedEncodingException {
UploadFileInfo uploadFileInfo = new UploadFileInfo();
for (FileItem item : items) {
if (item.isFormField()) {
// 获取分片数据
if ("chunk".equals(item.getFieldName())) {
uploadFileInfo.setCurrentChunk(Integer.parseInt(item.getString(UTF_8)));
}
if ("chunks".equals(item.getFieldName())) {
uploadFileInfo.setChunks(Integer.parseInt(item.getString(UTF_8)));
}
if ("name".equals(item.getFieldName())) {
uploadFileInfo.setFileName(item.getString(UTF_8));
}
}
}
return uploadFileInfo;
}
/**
* 写入临时文件
*
* @param items
* @param uploadFileInfo
* @throws Exception
*/
private void writeTempFile(List<FileItem> items, UploadFileInfo uploadFileInfo) throws Exception {
// 获取文件基本信息后
for (FileItem item : items) {
if (!item.isFormField()) {
// 有分片需要临时目录
String tempFileName = uploadFileInfo.getFileName();
if (StringUtils.isNotBlank(tempFileName)) {
if (uploadFileInfo.getCurrentChunk() != null) {
tempFileName = uploadFileInfo.getCurrentChunk() + "_" + uploadFileInfo.getFileName();
}
// 判断文件是否存在
File tempFile = new File(uploadPath, tempFileName);
// 断点续传，判断文件是否存在，若存在则不传
if (!tempFile.exists()) {
item.write(tempFile);
}
}
}
}
}
/**
* 判断是否合并
*
* @param uploadFileInfo
* @throws IOException
* @throws InterruptedException
*/
private void mergeFile(UploadFileInfo uploadFileInfo) throws IOException, InterruptedException {
Integer currentChunk = uploadFileInfo.getCurrentChunk();
Integer chunks = uploadFileInfo.getChunks();
String fileName = uploadFileInfo.getFileName();
// 如果当前分片等于总分片那么合并文件
if (currentChunk != null && chunks != null && currentChunk.equals(chunks - 1)) {
File tempFile = new File(uploadPath, fileName);
try (BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream(tempFile))) {
// 根据之前命名规则找到所有分片
for (int i = 0; i < chunks; i++) {
File file = new File(uploadPath, i + "_" + fileName);
// 并发情况，需要判断所有，因为可能最后一个分片传完，之前有的还没传完
while (!file.exists()) {
// 不存在休眠100毫秒后在重新判断
Thread.sleep(100);
}
// 分片存在，读入数组中
byte[] bytes = FileUtils.readFileToByteArray(file);
os.write(bytes);
os.flush();
file.delete();
}
os.flush();
}
}
}
/**
* 文件下载
*
* @param request
* @param response
* @throws IOException
*/
public void download(HttpServletRequest request, HttpServletResponse response) throws IOException {
// 获取文件
File file = new File(downloadFile);
// 获取下载文件信息
DownloadFileInfo downloadFileInfo = getDownloadFileInfo(file.length(), request, response);
// 设置响应头
setResponse(response, file.getName(), downloadFileInfo);
// 下载文件
try (InputStream is = new BufferedInputStream(new FileInputStream(file));
OutputStream os = new BufferedOutputStream(response.getOutputStream())) {
// 跳过已经读取文件
is.skip(downloadFileInfo.getPos());
byte[] buffer = new byte[1024];
long sum = 0;
// 读取
while (sum < downloadFileInfo.getRangeLength()) {
int length = is.read(buffer, 0, (downloadFileInfo.getRangeLength() - sum) <= buffer.length ? (int) (downloadFileInfo.getRangeLength() - sum) : buffer.length);
sum = sum + length;
os.write(buffer, 0, length);
}
}
}
/**
* 有两个map，我要去判断里面相同键的值一致不一致，除了双重for循环，有没有别的好办法
*/
private DownloadFileInfo getDownloadFileInfo(long fSize, HttpServletRequest request, HttpServletResponse response) {
long pos = 0;
long last = fSize - 1;
// 判断前端是否需要分片下载
if (request.getHeader(RANGE) != null) {
response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
String numRange = request.getHeader(RANGE).replace("bytes=", "");
String[] strRange = numRange.split("-");
if (strRange.length == 2) {
pos = Long.parseLong(strRange[0].trim());
last = Long.parseLong(strRange[1].trim());
// 若结束字节超出文件大小，取文件大小
if (last > fSize - 1) {
last = fSize - 1;
}
} else {
// 若只给一个长度，开始位置一直到结束
pos = Long.parseLong(numRange.replace("-", "").trim());
}
}
long rangeLength = last - pos + 1;
String contentRange = "bytes " + pos + "-" + last + "/" + fSize;
return new DownloadFileInfo(fSize, pos, last, rangeLength, contentRange);
}
/**
* 分片下载
*
* @throws IOException
*/
public void downloads() throws IOException {
File file = new File(downloadPath);
// 如果文件夹不存在则创建
if (!file.exists() && !file.isDirectory()) {
file.mkdirs();
}
// 探测下载，获取文件相关信息
FileInfo fileInfoDto = sliceDownload(1, 10, -1, null);
// 如果不为空，执行分片下载
if (fileInfoDto != null) {
// 计算有多少分片
long pages = fileInfoDto.getFileSize() / PER_SLICE;
// 适配最后一个分片
for (long i = 0; i <= pages; i++) {
long start = i * PER_SLICE;
long end = (i + 1) * PER_SLICE - 1;
executorService.execute(new SliceDownloadRunnable(start, end, i, fileInfoDto.getFileName()));
}
}
}
/**
* 分片下载
*
* @param start 分片起始位置
* @param end 分片结束位置
* @param page 第几个分片, page=-1时是探测下载
*/
private FileInfo sliceDownload(long start, long end, long page, String fName) throws IOException {
// 断点下载
File file = new File(downloadPath, page + "-" + fName);
// 如果当前文件已经存在，并且不是探测任务，并且文件的长度等于分片的大小，那么不用下载当前文件
if (file.exists() && page != -1 && file.length() == PER_SLICE) {
return null;
}
// 创建HttpClient
HttpClient client = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://localhost:8018/file/download");
httpGet.setHeader(RANGE, "bytes=" + start + "-" + end);
HttpResponse httpResponse = client.execute(httpGet);
String fSize = httpResponse.getFirstHeader("fSize").getValue();
fName = URLDecoder.decode(httpResponse.getFirstHeader("fName").getValue(), UTF_8);
HttpEntity entity = httpResponse.getEntity();
// 下载
try (InputStream is = entity.getContent();
FileOutputStream fos = new FileOutputStream(file)) {
byte[] buffer = new byte[1024];
int ch;
while ((ch = is.read(buffer)) != -1) {
fos.write(buffer, 0, ch);
}
fos.flush();
}
// 判断是否是最后一个分片，如果是那么合并
if (end - Long.parseLong(fSize) > 0) {
mergeFile(fName, page);
}
return new FileInfo(Long.parseLong(fSize), fName);
}
private void mergeFile(String fName, long page) throws IOException {
File file = new File(downloadPath, fName);
try (BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream(file))) {
for (int i = 0; i <= page; i++) {
File tempFile = new File(downloadPath, i + "-" + fName);
// 文件不存在或文件没写完
while (!tempFile.exists() || (i != page && tempFile.length() < PER_SLICE)) {
Thread.sleep(100);
}
byte[] bytes = FileUtils.readFileToByteArray(tempFile);
os.write(bytes);
os.flush();
tempFile.delete();
}
// 删除文件
File f = new File(downloadPath, "-1" + "-null");
if (f.exists()) {
f.delete();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private class SliceDownloadRunnable implements Runnable {
private final long start;
private final long end;
private final long page;
private final String fName;
private SliceDownloadRunnable(long start, long end, long page, String fName) {
this.start = start;
this.end = end;
this.page = page;
this.fName = fName;
}
@Override
public void run() {
try {
sliceDownload(start, end, page, fName);
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 设置响应头
*/
private void setResponse(HttpServletResponse response, String fileName, DownloadFileInfo downloadFileInfo) throws UnsupportedEncodingException {
response.setCharacterEncoding(UTF_8);
response.setContentType("application/x-download");
response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, UTF_8));
// 支持分片下载
response.setHeader("Accept-Range", "bytes");
response.setHeader("fSize", String.valueOf(downloadFileInfo.getFSize()));
response.setHeader("fName", URLEncoder.encode(fileName, UTF_8));
// range响应头
response.setHeader("Content-Range", downloadFileInfo.getContentRange());
response.setHeader("Content-Length", String.valueOf(downloadFileInfo.getRangeLength()));
}
}
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