Spring MVC 监听文件上传进度，实现上传进度条

首先Spring是一个非常成熟的J2EE框架，其非入侵式的架构为系统的集成和扩展提供了最大的可能。所以Spring MVC下实现进度监听非常容易，甚至不需要改以前的上传业务代码，具体实现分三个步骤：1、接管CommonsMultipartResolver，重写针对文件上传的请求。2、在第一步中写入监听，以获取上传进度。3、修改上传部分的配置文件。具体见代码1、CommonsMultipartResolver代码

package com.van.utils.upload.handle;

import java.util.List;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpSession;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.FileItemFactory;

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.web.multipart.MaxUploadSizeExceededException;

import org.springframework.web.multipart.MultipartException;

import org.springframework.web.multipart.MultipartHttpServletRequest;

import org.springframework.web.multipart.commons.CommonsMultipartResolver;

import com.van.utils.upload.listener.PJProgressListener;

/**

* 重写CommonsMultipartResolver以监听文件上传进度

* @author Van

* @date 2012-12-12

*/

public class PJCommonsMultipartResolver extends CommonsMultipartResolver {

private HttpServletRequest request;

protected FileUpload newFileUpload(FileItemFactory fileItemFactory) {

ServletFileUpload upload = new ServletFileUpload(fileItemFactory);

upload.setSizeMax(-1);

if (request != null) {

HttpSession session = request.getSession();

PJProgressListener uploadProgressListener = new PJProgressListener(session);

upload.setProgressListener(uploadProgressListener);

}

return upload;

}

public MultipartHttpServletRequest resolveMultipart(

HttpServletRequest request) throws MultipartException {

this.request = request;// 获取到request,要用到session

return super.resolveMultipart(request);

}

@SuppressWarnings("unchecked")

@Override

    public MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {

HttpSession session = request.getSession();

        String encoding = "utf-8";

        FileUpload fileUpload = prepareFileUpload(encoding);

        PJProgressListener uploadProgressListener = new PJProgressListener(session);

        fileUpload.setProgressListener(uploadProgressListener);

        try {

            List fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);

            return parseFileItems(fileItems, encoding);

        }

        catch (FileUploadBase.SizeLimitExceededException ex) {

            throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);

        }

        catch (FileUploadException ex) {

            throw new MultipartException("Could not parse multipart servlet request", ex);

        }

    }

}

PJProgressListener 代码：

package com.van.utils.upload.listener;

import javax.servlet.http.HttpSession;

import org.apache.commons.fileupload.ProgressListener;

import com.van.utils.upload.entity.ProgressEntity;

public class PJProgressListener implements ProgressListener{

private HttpSession session;

public PJProgressListener() {

}

public PJProgressListener(HttpSession _session) {

session=_session;

ProgressEntity ps = new ProgressEntity();

session.setAttribute("upload_ps", ps);

}

public void update(long pBytesRead, long pContentLength, int pItems) {

ProgressEntity ps = (ProgressEntity) session.getAttribute("upload_ps");

ps.setpBytesRead(pBytesRead);

ps.setpContentLength(pContentLength);

ps.setpItems(pItems);

//更新

session.setAttribute("upload_ps", ps);

}

}

上传进度信息记录实体类：

package com.van.utils.upload.entity;

/**

* 文件上传进度信息

* @author Van

*

*/

public class ProgressEntity {

private long pBytesRead = 0L;

private long pContentLength = 0L;

private int pItems;

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() {

return "ProgressEntity [pBytesRead=" + pBytesRead + ", pContentLength="

+ pContentLength + ", pItems=" + pItems + "]";

}

}

配置文件部分修改：

将org.springframework.web.multipart.commons.CommonsMultipartResolver替换成：com.van.utils.upload.handle.PJCommonsMultipartResolver

作者：Java高级技术
链接：https://www.jianshu.com/p/4680e5929366