SpringBoot+fileUpload獲取檔案上傳進度
我本人在網上找了很多關於檔案上傳進度獲取的文章,普遍基於spring MVC 框架通過 fileUpload 實現,對於spring Boot 通過 fileUpload 實現的帖子非常少,由於小弟學藝不精,雖然 Spring Boot 和 Spring MVC 相差不大,只是配置方式的差別,還是搞了很久,上傳此文章的目的是希望自己作為文字保留,以便日後檢視備忘,並且希望通過我的例子可以幫助到其他人而已,如果各位大佬發現小弟對於某些知識有誤解,還請不吝賜教,先謝謝各位前輩了!
寫此篇文章之前我查了很多關於spring MVC 框架通過 fileUpload 實現進度條的帖子和文章,在此對各位作者表示感謝!
此方法有一個問題,很嚴重的問題,就是隻能獲取當前伺服器上傳的總進度,沒法分使用者計算,不知道哪位前輩有辦法分使用者計算,煩請不吝賜教,謝謝各位前輩!
本功能基於commons fileUpload 元件實現
1.首先,不能在程式中直接使用 fileUpload.parseRequest(request)的方式來獲取 request 請求中的 multipartFile 檔案物件,原因是因為在 spring 預設的檔案上傳處理器 multipartResolver 指向的類CommonsMultipartResolver 中就是通過 commons fileUpload 元件實現的檔案獲取,因此,在程式碼中再次使用該方法,是獲取不到檔案物件的,因為此時的 request 物件是不包含檔案的,它已經被CommonsMultipartResolver 類解析處理並轉型。
CommonsMultipartResolver 類中相關原始碼片段:
protected MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException { String encoding = determineEncoding(request); FileUpload fileUpload = prepareFileUpload(encoding); try { List<FileItem> fileItems = ((ServletFileUpload) fileUpload).parseRequest(request); return parseFileItems(fileItems, encoding); } catch (FileUploadBase.SizeLimitExceededException ex) { throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex); } catch (FileUploadBase.FileSizeLimitExceededException ex) { throw new MaxUploadSizeExceededException(fileUpload.getFileSizeMax(), ex); } catch (FileUploadException ex) { throw new MultipartException("Failed to parse multipart servlet request", ex); } }
2.由於spring 中的 CommonsMultipartResolver 類中並沒有加入 processListener 檔案上傳進度監聽器,所以,直接使用 CommonsMultipartResolver 類是無法監聽檔案上傳進度的,如果我們需要獲取檔案上傳進度,就需要繼承 CommonsMultipartResolver 類並重寫 parseRequest 方法,在此之前,我們需要建立一個實現了 processListener 介面的實現類用於監聽檔案上傳進度。
processListener介面實現類:
import javax.servlet.http.HttpSession;
import org.apache.commons.fileupload.ProgressListener;
import org.springframework.stereotype.Component;
@Component
public class UploadProgressListener implements ProgressListener{
private HttpSession session;
public void setSession(HttpSession session){
this.session=session;
ProgressEntity status = new ProgressEntity();
session.setAttribute("status", status);
}
/*
* pBytesRead 到目前為止讀取檔案的位元數 pContentLength 檔案總大小 pItems 目前正在讀取第幾個檔案
*/
@Override
public void update(long pBytesRead, long pContentLength, int pItems) {
ProgressEntity status = (ProgressEntity) session.getAttribute("status");
status.setpBytesRead(pBytesRead);
status.setpContentLength(pContentLength);
status.setpItems(pItems);
}
}
ProgressEntity 實體類:
import org.springframework.stereotype.Component;
@Component
public class ProgressEntity {
private long pBytesRead = 0L; //到目前為止讀取檔案的位元數
private long pContentLength = 0L; //檔案總大小
private int pItems; //目前正在讀取第幾個檔案
public long getpBytesRead() {
return pBytesRead;
}
public void setpBytesRead(long pBytesRead) {
this.pBytesRead = pBytesRead;
}
public long getpContentLength() {
return pContentLength;
}
public void setpContentLength(long pContentLength) {
this.pContentLength = pContentLength;
}
public int getpItems() {
return pItems;
}
public void setpItems(int pItems) {
this.pItems = pItems;
}
@Override
public String toString() {
float tmp = (float)pBytesRead;
float result = tmp/pContentLength*100;
return "ProgressEntity [pBytesRead=" + pBytesRead + ", pContentLength="
+ pContentLength + ", percentage=" + result + "% , pItems=" + pItems + "]";
}
}
最後,是繼承 CommonsMultipartResolver 類的自定義檔案上傳處理類:
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUpload;
import org.apache.commons.fileupload.FileUploadBase;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.multipart.MaxUploadSizeExceededException;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
public class CustomMultipartResolver extends CommonsMultipartResolver{
@Autowired
private UploadProgressListener uploadProgressListener;
@Override
protected MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {
String encoding = determineEncoding(request);
FileUpload fileUpload = prepareFileUpload(encoding);
uploadProgressListener.setSession(request.getSession());//問檔案上傳進度監聽器設定session用於儲存上傳進度
fileUpload.setProgressListener(uploadProgressListener);//將檔案上傳進度監聽器加入到 fileUpload 中
try {
List<FileItem> fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);
return parseFileItems(fileItems, encoding);
}
catch (FileUploadBase.SizeLimitExceededException ex) {
throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);
}
catch (FileUploadBase.FileSizeLimitExceededException ex) {
throw new MaxUploadSizeExceededException(fileUpload.getFileSizeMax(), ex);
}
catch (FileUploadException ex) {
throw new MultipartException("Failed to parse multipart servlet request", ex);
}
}
}
3.此時,所有需要的類已經準備好,接下來我們需要將 spring 預設的檔案上傳處理類取消自動配置,並將 multipartResolver 指向我們剛剛建立好的繼承 CommonsMultipartResolver 類的自定義檔案上傳處理類。
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.web.MultipartAutoConfiguration;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.multipart.MultipartResolver;
import com.example.listener.CustomMultipartResolver;
/*
* 將 spring 預設的檔案上傳處理類取消自動配置,這一步很重要,沒有這一步,當multipartResolver重新指向了我們定義好
* 的新的檔案上傳處理類後,前臺傳回的 file 檔案在後臺獲取會是空,加上這句話就好了,推測不加這句話,spring 依然
* 會先走預設的檔案處理流程並修改request物件,再執行我們定義的檔案處理類。(這只是個人推測)
* exclude表示自動配置時不包括Multipart配置
*/
@EnableAutoConfiguration(exclude = {MultipartAutoConfiguration.class})
@Configuration
@ComponentScan(basePackages = {"com.example"})
@ServletComponentScan(basePackages = {"com.example"})
public class UploadProgressApplication {
/*
* 將 multipartResolver 指向我們剛剛建立好的繼承 CommonsMultipartResolver 類的自定義檔案上傳處理類
*/
@Bean(name = "multipartResolver")
public MultipartResolver multipartResolver() {
CustomMultipartResolver customMultipartResolver = new CustomMultipartResolver();
return customMultipartResolver;
}
public static void main(String[] args) {
SpringApplication.run(UploadProgressApplication.class, args);
}
}
至此,準備工作完成,我們再建立一個測試用的 controller 和 html 頁面用於檔案上傳。
controller:
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;
@Controller
@RequestMapping("/uploadProgress")
public class UploadController {
@RequestMapping(value = "/showUpload", method = RequestMethod.GET)
public ModelAndView showUpload() {
return new ModelAndView("/UploadProgressDemo");
}
@RequestMapping("/upload")
@ResponseBody
public void uploadFile(MultipartFile file) {
System.out.println(file.getOriginalFilename());
}
}
HTML:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8"></meta>
<title>測試</title>這裡寫程式碼片
</head>
<body>
這是檔案上傳頁面
<form action="/uploadProgress/upload" method="POST" enctype="multipart/form-data">
<input type="file" name="file"/>
<br/>
<input type="submit" value="提交"/>
</form>
</body>
</html>
經本人測試,確實可以獲取檔案上傳進度,前臺頁面修改進度條進度可以採用前臺頁面輪詢的方式訪問後臺,在相應action中通過儲存在session中的物件 status 來獲取最新的上傳進度並返回展示即可。