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sessionreturn 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;}@Overridepublic 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