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<fileitem> 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);
        }
    }

}

</fileitem>

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：

<!-- 文件上传支持  -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="UTF-8">
        <!-- 内存缓存1M -->
        <property name="maxInMemorySize" value="1000000"></property>
        <!-- 最大2GB -->
        <property name="maxUploadSize" value="2000000000"></property>
    </property></bean>

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