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超详细的文件上传和下载
前言Ⅰ：@RequestParam和@RequestPart的区别
@RequestPart
@RequestPart这个注解用在multipart/form-data表单提交请求的方法上。- 支持的请求方法的方式
MultipartFile，属于Spring的MultipartResolver类。这个请求是通过http协议传输的
@RequestParam
@RequestParam支持application/json，也同样支持multipart/form-data请求
代码演示
-
测试一：使用@RequestPart接收json数据
结论：
@RequestPart可以将jsonData的json数据转换为Person对象/** * 测试 RequestParam 和 RequestPart区别2 * @param person * @param file1 * @return * @throws IOException * @throws ServletException */ @RequestMapping(value = "/upload3",method = RequestMethod.POST) @ResponseBody public String readFile1(@RequestPart("person") Person person , @RequestPart("file1") MultipartFile file1) { StringBuilder sb = new StringBuilder(); sb.append(file1.getOriginalFilename()).append(";;;"); return person.toString() + ":::" + sb.toString(); }参数名 参数值 参数类型 file1 一个文件 file person {“name”:“cvzhanshi”,“age”:23} application/json 测试结果：能够用对象去接收json
-
测试二：使用@RequestParam接收json数据
结论：
@RequestParam对于jsonData的json数据只能用String字符串来接收/** * 测试 RequestParam 和 RequestPart区别2 * @param person * @param file1 * @return * @throws IOException * @throws ServletException */ @RequestMapping(value = "/upload3",method = RequestMethod.POST) @ResponseBody public String readFile1(@RequestParam("person") Person person , @RequestPart("file1") MultipartFile file1) { StringBuilder sb = new StringBuilder(); sb.append(file1.getOriginalFilename()).append(";;;"); return person.toString() + ":::" + sb.toString(); }
测试结果：报错 2022-10-08 10:19:48.434 WARN 3440 — [nio-8888-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.method.annotation.MethodArgumentConversionNotSupportedException: Failed to convert value of type ‘java.lang.String’ to required type ‘cn.cvzhanshi.test.entity.Person’; nested exception is java.lang.IllegalStateException: Cannot convert value of type ‘java.lang.String’ to required type ‘cn.cvzhanshi.test.entity.Person’: no matching editors or conversion strategy found]
报错说明：只能接收解析String类型的
区别(总结)
- 当请求为
multipart/form-data时，@RequestParam只能接收String类型的name-value值，@RequestPart可以接收复杂的请求域（像json、xml） @RequestParam依赖Converter or PropertyEditor进行数据解析，@RequestPart参考'Content-Type' header，依赖HttpMessageConverters进行数据解析- 当请求头中指定Content-Type:multipart/form-data时，传递的json参数，@RequestPart注解可以用对象来接收，@RequestParam只能用字符串接收
- @RequestParam适用于name-valueString类型的请求域，@RequestPart适用于复杂的请求域（像JSON，XML）；他们最大的不同是，当请求方法的请求参数类型不再是String类型的时候
前言Ⅱ：getParameter() 和 getPart() 区别
代码测试
/**
* 测试 RequestParam 和 RequestPart区别1
* @param request
* @param name
* @param file1
* @return
* @throws IOException
* @throws ServletException
*/
@RequestMapping(value = "/upload1",method = RequestMethod.POST)
@ResponseBody
public String readFile(HttpServletRequest request,@RequestParam("name") String name ,@RequestPart("file1") MultipartFile file1) throws IOException, ServletException {
String ageParameter = request.getParameter("age");
Part agePart = request.getPart("age");
String file2Parameter = request.getParameter("file2");
Part file2Part = request.getPart("file2");
Enumeration<String> parameterNames = request.getParameterNames();
Collection<Part> parts = request.getParts();
return "";
}
传递参数
| key | value | type |
|---|---|---|
| name | cvzhanshi | text |
| age | 18 | text |
| file1 | 新建文本文档.txt | file |
| file2 | 美女.jpg | file |
DeBug分析：
-
request：可以看到request有两个 Parameter 和 两个 Part 参数
-
Parameter和Part：request.getParameter获得的值以及request.getPart获得的值
结果发现：使用 request.getParameter() 获取文件类型参数为空，使用 request.getPart() 获取非文件类型为空
-
ParameterNames和Parts：getParameterNames()和getParts()获取参数名
结果：使用 request.getParameterNames() 只能获取非文件类型的参数名, 使用 request.getParts() 可以获取全部参数名
结论
- Part 能获取所有的请求参数的参数名，而 Parameter 只能获取非文件类型的参数名
- Part 不能获得非文件类型参数的参数值，Part获得二进制的输入流
- Parameter 只能获得非文件类型参数值
- 使用 Part 获取文件很方便，可以获取文件大小文件类型
Ⅰ：文件上传
① form-data 类型上传
form-data 类型即常用的表单提交，可以通过两种方式接收前端传过来的文件
- 通过上述讲的Part 接收字节流，即@RequestPart注解以及request.getParts()
- 通过MultipartFile类来接收前端传过来的文件
说明：两种方法差不多
前端接口提交
上传文件的后端代码（接口）
/**
* form-data 类型(前端表单上传)
* @param request
* @param name
* @param file3
* @param photo
* @return
* @throws IOException
* @throws ServletException
*/
@RequestMapping(value = "/upload", method = RequestMethod.POST)
@ResponseBody
public String readFile(HttpServletRequest request,
@RequestParam("name") String name,
@RequestPart("file1") MultipartFile file3,
@RequestPart("photo") MultipartFile photo
) throws IOException, ServletException {
System.out.println(name);
/*
第一种 ： 使用 MultipartFile 封装好的 transferTo() 方法保存文件
photo.transferTo(new File(path + photo.getOriginalFilename()));
*/
/*
第二种 ： 使用 MultipartFile 字节流保存文件
fileUtil(file3, String.valueOf(path));
*/
/*第三种 ：用 Part 接收文件字节流
Part file2 = request.getPart("file2");
file2.write(path + file2.getSubmittedFileName());
request.getParts() 获取的是全部参数（name,age,file1,file2），包括文件参数和非文件参数
*/
for (Part part : request.getParts()) {
// 获取文件类型
part.getContentType();
// 获取文件大小
part.getSize();
// 获取文件名
part.getSubmittedFileName();
// 获取参数名 （name,age,file1,file2）
part.getName();
if(part.getContentType()!=null){
part.write(path + part.getSubmittedFileName());
}else{
// 可以获取文本参数值,文本参数 part.getContentType()为 null
System.out.println(request.getParameter(part.getName()));
}
}
return "success";
}
/**
* 字节流上传文件工具方法
* @param file
* @param path
* @return
*/
public String fileUtil(MultipartFile file, String path) {
if (!file.isEmpty()) {
try {
// 转化成字节流
byte[] bytes = file.getBytes();
bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(
new File(path + file.getOriginalFilename())));
// 写出
bufferedOutputStream.write(bytes);
// 关闭资源
bufferedOutputStream.close();
return file.getOriginalFilename() + " 上传成功";
} catch (Exception e) {
return file.getOriginalFilename() + " failed to upload ---> " + e;
}
} else {
return file.getOriginalFilename() + "You failed to upload file was empty.";
}
}
测试
② binary 类型上传
binary 这一类型，指的就是一些二进制文件类型，如application/pdf，指定了特定二进制文件的MIME类型。就像对于text文件类型若没有特定的子类型
（subtype），就使用 text/plain。类似的，二进制文件没有特定或已知的 subtype，即使用 application/octet-stream，这是应用程序文件的默认值。
对于application/octet-stream，只能提交二进制，而且只能提交一个二进制，如果提交文件的话，只能提交一个文件，后台接收参数只能有一个，而且只能是流
（或者字节数组）
前端接口提交
上传文件的后端代码（接口）
/**
* binary 类型上传
* @param request
* @return
* @throws IOException
*/
@RequestMapping(value = "/upload2",method = RequestMethod.POST)
public String upload2(HttpServletRequest request) throws IOException {
ServletInputStream inputStream = null;
FileOutputStream fileOutputStream = null;
try {
// 获取上传的文件流
inputStream = request.getInputStream();
// 定义输出流 上传到哪里
fileOutputStream = new FileOutputStream(new File(path + "a.pdf"));
int len;
byte[] bytes = new byte[1024];
while((len = inputStream.read(bytes))!=-1){
fileOutputStream.write(bytes,0,len);
}
} catch (IOException e) {
e.printStackTrace();
return "上传失败";
} finally {
// 关闭资源
if(fileOutputStream!=null){
fileOutputStream.close();
}
if(inputStream!=null){
inputStream.close();
}
}
return "上传成功";
}
测试
说明：part 使用起来比较方便，接受的就是字节流，读取文件类型，文件名，文件大小也比较方便
③ 配置说明
如果不自定义配置的话，他会默认上传大小1M\
SpringBoot项目的话通过配置文件配置
server:
port: 8888
spring:
servlet:
multipart:
max-file-size: 10MB # 最大上传大小
max-request-size: 100MB # 单文件最大上传大小
Ⅱ：文件下载
① 补充说明
Content-Disposition
- 在常规的 HTTP 应答中，
Content-Disposition响应头指示回复的内容该以何种形式展示，是以内联的形式（即网页或者页面的一部分），还是以附件的形式下载并保存到本地 - 在 multipart/form-data 类型的应答消息体中，
Content-Disposition消息头可以被用在 multipart 消息体的子部分中，用来给出其对应字段的相关信息。各个子部分由在Content-Type中定义的分隔符分隔。用在消息体自身则无实际意义。
语法：
-
作为消息主体中的消息头：在 HTTP 场景中，第一个参数或者是
inline（默认值，表示回复中的消息体会以页面的一部分或者整个页面的形式展示），或者是attachment（意味着消息体应该被下载到本地；大多数浏览器会呈现一个“保存为”的对话框，将filename的值预填为下载后的文件名，假如它存在的话）。Content-Disposition: inline Content-Disposition: attachment Content-Disposition: attachment; filename="filename.jpg" -
作为 multipart body 中的消息头：在 HTTP 场景中。第一个参数总是固定不变的
form-data；附加的参数不区分大小写，并且拥有参数值，参数名与参数值用等号 ('=') 连接，参数值用双引号括起来。参数之间用分号 (';') 分隔。Content-Disposition: form-data Content-Disposition: form-data; name="fieldName" Content-Disposition: form-data; name="fieldName"; filename="filename.jpg"
response.setContentType()的String参数及对应类型
| 文件扩展名 | Content-Type(Mime-Type) | 文件扩展名 | Content-Type(Mime-Type) |
|---|---|---|---|
| .*（ 二进制流，不知道下载文件类型） | application/octet-stream | .tif | image/tiff |
| .001 | application/x-001 | .301 | application/x-301 |
| .323 | text/h323 | .906 | application/x-906 |
| .907 | drawing/907 | .a11 | application/x-a11 |
| .acp | audio/x-mei-aac | .ai | application/postscript |
| .aif | audio/aiff | .aifc | audio/aiff |
| .aiff | audio/aiff | .anv | application/x-anv |
| .asa | text/asa | .asf | video/x-ms-asf |
| .asp | text/asp | .asx | video/x-ms-asf |
| .au | audio/basic | .avi | video/avi |
| .awf | application/vnd.adobe.workflow | .biz | text/xml |
| .bmp | application/x-bmp | .bot | application/x-bot |
| .c4t | application/x-c4t | .c90 | application/x-c90 |
| .cal | application/x-cals | .cat | application/vnd.ms-pki.seccat |
| .cdf | application/x-netcdf | .cdr | application/x-cdr |
| .cel | application/x-cel | .cer | application/x-x509-ca-cert |
| .cg4 | application/x-g4 | .cgm | application/x-cgm |
| .cit | application/x-cit | .class | java/* |
| .cml | text/xml | .cmp | application/x-cmp |
| .cmx | application/x-cmx | .cot | application/x-cot |
| .crl | application/pkix-crl | .crt | application/x-x509-ca-cert |
| .csi | application/x-csi | .css | text/css |
| .cut | application/x-cut | .dbf | application/x-dbf |
| .dbm | application/x-dbm | .dbx | application/x-dbx |
| .dcd | text/xml | .dcx | application/x-dcx |
| .der | application/x-x509-ca-cert | .dgn | application/x-dgn |
| .dib | application/x-dib | .dll | application/x-msdownload |
| .doc | application/msword | .dot | application/msword |
| .drw | application/x-drw | .dtd | text/xml |
| .dwf | Model/vnd.dwf | .dwf | application/x-dwf |
| .dwg | application/x-dwg | .dxb | application/x-dxb |
| .dxf | application/x-dxf | .edn | application/vnd.adobe.edn |
| .emf | application/x-emf | .eml | message/rfc822 |
| .ent | text/xml | .epi | application/x-epi |
| .eps | application/x-ps | .eps | application/postscript |
| .etd | application/x-ebx | .exe | application/x-msdownload |
| .fax | image/fax | .fdf | application/vnd.fdf |
| .fif | application/fractals | .fo | text/xml |
| .frm | application/x-frm | .g4 | application/x-g4 |
| .gbr | application/x-gbr | . | application/x- |
| .gif | image/gif | .gl2 | application/x-gl2 |
| .gp4 | application/x-gp4 | .hgl | application/x-hgl |
| .hmr | application/x-hmr | .hpg | application/x-hpgl |
| .hpl | application/x-hpl | .hqx | application/mac-binhex40 |
| .hrf | application/x-hrf | .hta | application/hta |
| .htc | text/x-component | .htm | text/html |
| .html | text/html | .htt | text/webviewhtml |
| .htx | text/html | .icb | application/x-icb |
| .ico | image/x-icon | .ico | application/x-ico |
| .iff | application/x-iff | .ig4 | application/x-g4 |
| .igs | application/x-igs | .iii | application/x-iphone |
| .img | application/x-img | .ins | application/x-internet-signup |
| .isp | application/x-internet-signup | .IVF | video/x-ivf |
| .java | java/* | .jfif | image/jpeg |
| .jpe | image/jpeg | .jpe | application/x-jpe |
| .jpeg | image/jpeg | .jpg | image/jpeg |
| .jpg | application/x-jpg | .js | application/x-javascript |
| .jsp | text/html | .la1 | audio/x-liquid-file |
| .lar | application/x-laplayer-reg | .latex | application/x-latex |
| .lavs | audio/x-liquid-secure | .lbm | application/x-lbm |
| .lmsff | audio/x-la-lms | .ls | application/x-javascript |
| .ltr | application/x-ltr | .m1v | video/x-mpeg |
| .m2v | video/x-mpeg | .m3u | audio/mpegurl |
| .m4e | video/mpeg4 | .mac | application/x-mac |
| .man | application/x-troff-man | .math | text/xml |
| .mdb | application/msaccess | .mdb | application/x-mdb |
| .mfp | application/x-shockwave-flash | .mht | message/rfc822 |
| .mhtml | message/rfc822 | .mi | application/x-mi |
| .mid | audio/mid | .midi | audio/mid |
| .mil | application/x-mil | .mml | text/xml |
| .mnd | audio/x-musicnet-download | .mns | audio/x-musicnet-stream |
| .mocha | application/x-javascript | .movie | video/x-sgi-movie |
| .mp1 | audio/mp1 | .mp2 | audio/mp2 |
| .mp2v | video/mpeg | .mp3 | audio/mp3 |
| .mp4 | video/mpeg4 | .mpa | video/x-mpg |
| .mpd | application/vnd.ms-project | .mpe | video/x-mpeg |
| .mpeg | video/mpg | .mpg | video/mpg |
| .mpga | audio/rn-mpeg | .mpp | application/vnd.ms-project |
| .mps | video/x-mpeg | .mpt | application/vnd.ms-project |
| .mpv | video/mpg | .mpv2 | video/mpeg |
| .mpw | application/vnd.ms-project | .mpx | application/vnd.ms-project |
| .mtx | text/xml | .mxp | application/x-mmxp |
| image/pnetvue | .nrf | application/x-nrf | |
| .nws | message/rfc822 | .odc | text/x-ms-odc |
| .out | application/x-out | .p10 | application/pkcs10 |
| .p12 | application/x-pkcs12 | .p7b | application/x-pkcs7-certificates |
| .p7c | application/pkcs7-mime | .p7m | application/pkcs7-mime |
| .p7r | application/x-pkcs7-certreqresp | .p7s | application/pkcs7-signature |
| .pc5 | application/x-pc5 | .pci | application/x-pci |
| .pcl | application/x-pcl | .pcx | application/x-pcx |
| application/pdf | application/pdf | ||
| .pdx | application/vnd.adobe.pdx | .pfx | application/x-pkcs12 |
| .pgl | application/x-pgl | .pic | application/x-pic |
| .pko | application/vnd.ms-pki.pko | .pl | application/x-perl |
| .plg | text/html | .pls | audio/scpls |
| .plt | application/x-plt | .png | image/png |
| .png | application/x-png | .pot | application/vnd.ms-powerpoint |
| .ppa | application/vnd.ms-powerpoint | .ppm | application/x-ppm |
| .pps | application/vnd.ms-powerpoint | .ppt | application/vnd.ms-powerpoint |
| .ppt | application/x-ppt | .pr | application/x-pr |
| .prf | application/pics-rules | .prn | application/x-prn |
| .prt | application/x-prt | .ps | application/x-ps |
| .ps | application/postscript | .ptn | application/x-ptn |
| .pwz | application/vnd.ms-powerpoint | .r3t | text/vnd.rn-realtext3d |
| .ra | audio/vnd.rn-realaudio | .ram | audio/x-pn-realaudio |
| .ras | application/x-ras | .rat | application/rat-file |
| .rdf | text/xml | .rec | application/vnd.rn-recording |
| .red | application/x-red | .rgb | application/x-rgb |
| .rjs | application/vnd.rn-realsystem-rjs | .rjt | application/vnd.rn-realsystem-rjt |
| .rlc | application/x-rlc | .rle | application/x-rle |
| .rm | application/vnd.rn-realmedia | .rmf | application/vnd.adobe.rmf |
| .rmi | audio/mid | .rmj | application/vnd.rn-realsystem-rmj |
| .rmm | audio/x-pn-realaudio | .rmp | application/vnd.rn-rn_music_package |
| .rms | application/vnd.rn-realmedia-secure | .rmvb | application/vnd.rn-realmedia-vbr |
| .rmx | application/vnd.rn-realsystem-rmx | .rnx | application/vnd.rn-realplayer |
| .rp | image/vnd.rn-realpix | .rpm | audio/x-pn-realaudio-plugin |
| .rsml | application/vnd.rn-rsml | .rt | text/vnd.rn-realtext |
| .rtf | application/msword | .rtf | application/x-rtf |
| .rv | video/vnd.rn-realvideo | .sam | application/x-sam |
| .sat | application/x-sat | .sdp | application/sdp |
| .sdw | application/x-sdw | .sit | application/x-stuffit |
| .slb | application/x-slb | .sld | application/x-sld |
| .slk | drawing/x-slk | .smi | application/smil |
| .smil | application/smil | .smk | application/x-smk |
| .snd | audio/basic | .sol | text/plain |
| .sor | text/plain | .spc | application/x-pkcs7-certificates |
| .spl | application/futuresplash | .spp | text/xml |
| .ssm | application/streamingmedia | .sst | application/vnd.ms-pki.certstore |
| .stl | application/vnd.ms-pki.stl | .stm | text/html |
| .sty | application/x-sty | .svg | text/xml |
| .swf | application/x-shockwave-flash | .tdf | application/x-tdf |
| .tg4 | application/x-tg4 | .tga | application/x-tga |
| .tif | image/tiff | .tif | application/x-tif |
| .tiff | image/tiff | .tld | text/xml |
| .top | drawing/x-top | .torrent | application/x-bittorrent |
| .tsd | text/xml | .txt | text/plain |
| .uin | application/x-icq | .uls | text/iuls |
| .vcf | text/x-vcard | .vda | application/x-vda |
| .vdx | application/vnd.visio | .vml | text/xml |
| .vpg | application/x-vpeg005 | .vsd | application/vnd.visio |
| .vsd | application/x-vsd | .vss | application/vnd.visio |
| .vst | application/vnd.visio | .vst | application/x-vst |
| .vsw | application/vnd.visio | .vsx | application/vnd.visio |
| .vtx | application/vnd.visio | .vxml | text/xml |
| .wav | audio/wav | .wax | audio/x-ms-wax |
| .wb1 | application/x-wb1 | .wb2 | application/x-wb2 |
| .wb3 | application/x-wb3 | .wbmp | image/vnd.wap.wbmp |
| .wiz | application/msword | .wk3 | application/x-wk3 |
| .wk4 | application/x-wk4 | .wkq | application/x-wkq |
| .wks | application/x-wks | .wm | video/x-ms-wm |
| .wma | audio/x-ms-wma | .wmd | application/x-ms-wmd |
| .wmf | application/x-wmf | .wml | text/vnd.wap.wml |
| .wmv | video/x-ms-wmv | .wmx | video/x-ms-wmx |
| .wmz | application/x-ms-wmz | .wp6 | application/x-wp6 |
| .wpd | application/x-wpd | .wpg | application/x-wpg |
| .wpl | application/vnd.ms-wpl | .wq1 | application/x-wq1 |
| .wr1 | application/x-wr1 | .wri | application/x-wri |
| .wrk | application/x-wrk | .ws | application/x-ws |
| .ws2 | application/x-ws | .wsc | text/scriptlet |
| .wsdl | text/xml | .wvx | video/x-ms-wvx |
| .xdp | application/vnd.adobe.xdp | .xdr | text/xml |
| .xfd | application/vnd.adobe.xfd | .xfdf | application/vnd.adobe.xfdf |
| .xhtml | text/html | .xls | application/vnd.ms-excel |
| .xls | application/x-xls | .xlw | application/x-xlw |
| .xml | text/xml | .xpl | audio/scpls |
| .xq | text/xml | .xql | text/xml |
| .xquery | text/xml | .xsd | text/xml |
| .xsl | text/xml | .xslt | text/xml |
| .xwd | application/x-xwd | .x_b | application/x-x_b |
| .sis | application/vnd.symbian.install | .sisx | application/vnd.symbian.install |
| .x_t | application/x-x_t | .ipa | application/vnd.iphone |
| .apk | application/vnd.android.package-archive | .xap | application/x-silverlight-app |
② 下载本地资源
下载代码
/**
* 下载本地资源
* @param fileName 下载的文件名
* @param response 响应头
* @param isOnLine 是否默认下载 true浏览器中打开
* @throws IOException
*/
@GetMapping("/download")
public void download(String fileName, HttpServletResponse response, boolean isOnLine) throws IOException {
// 路径可以指定当前项目相对路径
File file = new File(path + fileName);
if (file.exists()) {
// 把文件转化成流
FileInputStream fileInputStream = new FileInputStream(file);
ServletOutputStream outputStream = response.getOutputStream();
// 是否立即下载
if(!isOnLine){
response.setContentType("application/octet-stream");
// 如果文件名为中文需要设置编码
response.setHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode("背景.jpg", "utf8"));
}
byte[] bytes = new byte[1024];
int len;
// 把文件流写入响应头
while ((len = fileInputStream.read(bytes)) != -1) {
outputStream.write(bytes, 0, len);
}
}
}
测试链接：http://localhost:8888/download?fileName=背景.jpg
或者http://localhost:8888/download?isOnLine=true&fileName=背景.jpg
③ 下载网络资源
代码演示
说明：首先要获取到正确的url才能获取到想要的资源
/**
* 下载网络资源
* @param response
* @throws IOException
*/
@RequestMapping("/downLoadMusic")
public void downloadNetworkFile(HttpServletResponse response) throws IOException {
// 创建url对象
URL url = new URL("https://m701.music.126/20221009103058/70acd1fa2256e82ae0a90f833aec1072/jdyyaac/obj/w5rDlsOJwrLDjj7CmsOj/18195365565/53a1/ad15/9e1c/1b3457995065a152f56f61c38eda1914.m4a");
// 建立连接
URLConnection urlConnection = url.openConnection();
// 获取到输入流
InputStream inputStream = urlConnection.getInputStream();
// 获取到响应头的输出流
ServletOutputStream outputStream = response.getOutputStream();
// 设置响应头
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition","attachment;fileName=" + URLEncoder.encode("爱似水仙.m4a", "utf8"));
int len;
// 通过字节流下载下来
byte[] bytes = new byte[1024];
while ((len = inputStream.read(bytes)) != -1){
outputStream.write(bytes,0, len);
}
// 关闭资源
inputStream.close();
outputStream.close();
}
测试链接：http://localhost:8888/downLoadMusic
参考文章1
参考文章2
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