这篇文章主要介绍了spring boot如何实现切割分片上传,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下
文件上传是web开发中经常会遇到的
springboot的默认配置为10MB，大于10M的是传不上服务器的，需要修改默认配置
但是如果修改支持大文件又会增加服务器的负担。
当文件大于一定程度时，不仅服务器会占用大量内存，而且http传输极可能会中断。
可以采用切割分片上传
html5提供的文件API中可以轻松的对文件进行分割切片，然后通过ajax异步处理向服务器传输数据，突破对大文件上传的限制，
同时异步处理在一定程度上也提高了文件上传的效率。
过程描述：
1.服务端
（1）添加依赖
<dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3.3</version> </dependency>
（2）UploadController
package com.example.demo.controller;
import com.example.demo.core.Result;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FileUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
@CrossOrigin
@Controller
@RequestMapping("/api/upload")
public class UploadController {
@PostMapping("/part")
@ResponseBody
public Result bigFile(HttpServletRequest request, HttpServletResponse response, String guid, Integer chunk, MultipartFile file, Integer chunks) {
try {
String projectUrl = System.getProperty("user.dir").replaceAll("\\\\", "/");
;
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if (isMultipart) {
if (chunk == null) chunk = 0;
// 临时目录用来存放所有分片文件
String tempFileDir = projectUrl + "/upload/" + guid;
File parentFileDir = new File(tempFileDir);
if (!parentFileDir.exists()) {
parentFileDir.mkdirs();
}
// 分片处理时，前台会多次调用上传接口，每次都会上传文件的一部分到后台
File tempPartFile = new File(parentFileDir, guid + "_" + chunk + ".part");
FileUtils.copyInputStreamToFile(file.getInputStream(), tempPartFile);
}
} catch (Exception e) {
return Result.failMessage(400,e.getMessage());
}
return Result.successMessage(200,"上次成功");
}
@RequestMapping("merge")
@ResponseBody
public Result mergeFile(String guid, String fileName) {
// 得到 destTempFile 就是最终的文件
String projectUrl = System.getProperty("user.dir").replaceAll("\\\\", "/");
try {
String sname = fileName.substring(fileName.lastIndexOf("."));
//时间格式化格式
Date currentTime = new Date();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMddHHmmssSSS");
//获取当前时间并作为时间戳
String timeStamp = simpleDateFormat.format(currentTime);
//拼接新的文件名
String newName = timeStamp + sname;
simpleDateFormat = new SimpleDateFormat("yyyyMM");
String path = projectUrl + "/upload/";
String tmp = simpleDateFormat.format(currentTime);
File parentFileDir = new File(path + guid);
if (parentFileDir.isDirectory()) {
File destTempFile = new File(path + tmp, newName);
if (!destTempFile.exists()) {
//先得到文件的上级目录，并创建上级目录，在创建文件
destTempFile.getParentFile().mkdir();
try {
destTempFile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
for (int i = 0; i < parentFileDir.listFiles().length; i++) {
File partFile = new File(parentFileDir, guid + "_" + i + ".part");
FileOutputStream destTempfos = new FileOutputStream(destTempFile, true);
//遍历"所有分片文件"到"最终文件"中
FileUtils.copyFile(partFile, destTempfos);
destTempfos.close();
}
// 删除临时目录中的分片文件
FileUtils.deleteDirectory(parentFileDir);
return Result.successMessage(200,"合并成功");
}else{
return Result.failMessage(400,"没找到目录");
}
} catch (Exception e) {
return Result.failMessage(400,e.getMessage());
}
}
}
说明：
注解 @CrossOrigin 解决跨域问题
（3）Result
package com.example.demo.core;
import com.alibaba.fastjson.JSON;
/**
* Created by Beibei on 19/02/22
* API响应结果
*/
public class Result<T> {
private int code;
private String message;
private T data;
public Result setCode(Integer code) {
this.code = code;
return this;
}
public int getCode() {
return code;
}
public String getMessage() {
return message;
}
public Result setMessage(String message) {
this.message = message;
return this;
}
public T getData() {
return data;
}
public Result setData(T data) {
this.data = data;
return this;
}
@Override
public String toString() {
return JSON.toJSONString(this);
}
public static <T> Result<T> fail(Integer code,T data) {
Result<T> ret = new Result<T>();
ret.setCode(code);
ret.setData(data);
return ret;
}
public static <T> Result<T> failMessage(Integer code,String msg) {
Result<T> ret = new Result<T>();
ret.setCode(code);
ret.setMessage(msg);
return ret;
}
public static <T> Result<T> successMessage(Integer code,String msg) {
Result<T> ret = new Result<T>();
ret.setCode(code);
ret.setMessage(msg);
return ret;
}
public static <T> Result<T> success(Integer code,T data) {
Result<T> ret = new Result<T>();
ret.setCode(code);
ret.setData(data);
return ret;
}
}
2.前端
（1）使用插件
webuploader，下载 https://github.com/fex-team/webuploader/releases
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link href="css/webuploader.css" rel="external nofollow" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="jquery-1.10.1.min.js"></script>
<script type="text/javascript" src="dist/webuploader.min.js"></script>
</head>
<body>
<div id="uploader">
<div class="btns">
<div id="picker">选择文件</div>
<button id="startBtn" class="btn btn-default">开始上传</button>
</div>
</div>
</body>
<script type="text/javascript">
var GUID = WebUploader.Base.guid();//一个GUID
var uploader = WebUploader.create({
// swf文件路径
swf: 'dist/Uploader.swf',
// 文件接收服务端。
server: 'http://localhost:8080/api/upload/part',
formData:{
guid : GUID
},
pick: '#picker',
chunked : true, // 分片处理
chunkSize : 1 * 1024 * 1024, // 每片1M,
chunkRetry : false,// 如果失败，则不重试
threads : 1,// 上传并发数。允许同时最大上传进程数。
resize: false
});
$("#startBtn").click(function () {
uploader.upload();
});
//当文件上传成功时触发。
uploader.on( "uploadSuccess", function( file ) {
$.post('http://localhost:8080/api/upload/merge', { guid: GUID, fileName: file.name}, function (data) {
if(data.code == 200){
alert('上传成功!');
}
});
});
</script>
</html>
（2）不使用插件
直接用HTML5的File API
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script src="jquery-1.10.1.min.js" type="text/javascript">
</script>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type"/>
</head>
<body>
<div id="uploader">
<div class="btns">
<input id="file" name="file" type="file"/>
<br>
<br>
<button id="startBtn">
开始上传
</button>
</br>
</br>
</div>
<div id="output">
</div>
</div>
</body>
<script type="text/javascript">
var status = 0;
var page = {
init: function(){
$("#startBtn").click($.proxy(this.upload, this));
},
upload: function(){
status = 0;
var GUID = this.guid();
var file = $("#file")[0].files[0], //文件对象
name = file.name, //文件名
size = file.size; //总大小
var shardSize = 20 * 1024 * 1024, //以1MB为一个分片
shardCount = Math.ceil(size / shardSize); //总片数
for(var i = 0;i < shardCount;++i){
//计算每一片的起始与结束位置
var start = i * shardSize,
end = Math.min(size, start + shardSize);
var partFile = file.slice(start,end);
this.partUpload(GUID,partFile,name,shardCount,i);
}
},
partUpload:function(GUID,partFile,name,chunks,chunk){
//构造一个表单，FormData是HTML5新增的
var now = this;
var form = new FormData();
form.append("guid", GUID);
form.append("file", partFile); //slice方法用于切出文件的一部分
form.append("fileName", name);
form.append("chunks", chunks); //总片数
form.append("chunk", chunk); //当前是第几片
//Ajax提交
$.ajax({
url: "http://localhost:8080/api/upload/part",
type: "POST",
data: form,
async: true, //异步
processData: false, //很重要，告诉jquery不要对form进行处理
contentType: false, //很重要，指定为false才能形成正确的Content-Type
success: function(data){
status++;
if(data.code == 200){
$("#output").html(status+ " / " + chunks);
}
if(status==chunks){
now.mergeFile(GUID,name);
}
}
});
},
mergeFile:function(GUID,name){
var formMerge = new FormData();
formMerge.append("guid", GUID);
formMerge.append("fileName", name);
$.ajax({
url: "http://localhost:8080/api/upload/merge",
type: "POST",
data: formMerge,
processData: false, //很重要，告诉jquery不要对form进行处理
contentType: false, //很重要，指定为false才能形成正确的Content-Type
success: function(data){
if(data.code == 200){
alert('上传成功!');
}
}
});
},
guid:function(prefix){
var counter = 0;
var guid = (+new Date()).toString( 32 ),
i = 0;
for ( ; i < 5; i++ ) {
guid += Math.floor( Math.random() * 65535 ).toString( 32 );
}
return (prefix || 'wu_') + guid + (counter++).toString( 32 );
}
};
$(function(){
page.init();
});
</script>
</html>
3.优化
springboot的默认配置为10MB，前端分片改为20M时，就会报错
org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (10486839) exceeds the configured maximum (10485760)
解决方法：
在 src/main/resources 下的 application.properties里添加
spring.servlet.multipart.max-file-size=30MB spring.servlet.multipart.max-request-size=35MB
说明:
设置的数值虽好比前端传过来的大，要不容易报错
