两种思路，一种是使用plupload插件，使用插件就比较简单，进度在前端实现，plupload记录发送的文件大小并提供函数。具体可参考http://www.plupload.com/官网。
另一种就是在后台监听接收数据，前台使用ajax轮回实时读取展示进度信息。
本文旨在叙述第二种方法后台方法。
环境：前台上传插件http://www.jq22.com/jquery-info13450，后台Structs。（注插件提供了springmvc版本的进度显示）
1、定义返回信息实体类
public class UploadStatus {
private long bytesRead;//已读数据
private long contentLength;//文件总数据
private long items;//第几个文件
private long startTime = System.currentTimeMillis();//开始时间
private long useTime = System.currentTimeMillis();//已用时间
private int percent;//完成百分比
public long getBytesRead() {
return bytesRead;
}
public void setBytesRead(long bytesRead) {
this.bytesRead = bytesRead;
}
public long getContentLength() {
return contentLength;
}
public void setContentLength(long contentLength) {
this.contentLength = contentLength;
}
public long getItems() {
return items;
}
public void setItems(long items) {
this.items = items;
}
public long getStartTime() {
return startTime;
}
public void setStartTime(long startTime) {
this.startTime = startTime;
}
public long getUseTime() {
return useTime;
}
public void setUseTime(long useTime) {
this.useTime = useTime;
}
public int getPercent() {
return percent;
}
public void setPercent(int percent) {
this.percent = percent;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return "UploadStatus [percent=" + percent + ", items=" + items + "]";
}
}
2、创建监听类实现ProgressListener
import javax.servlet.http.HttpSession;
import org.apache.commons.fileupload.ProgressListener;
public class UploadListener implements ProgressListener{
private HttpSession session;
public UploadListener(HttpSession session){
super();
this.session = session;
UploadStatus uploadStatus = new UploadStatus();
session.setAttribute("upload_status", uploadStatus);
}
@Override
public void update(long bytesRead, long contentLength, int items) {
// TODO Auto-generated method stub
UploadStatus uploadStatus = (UploadStatus) session.getAttribute("upload_status");
uploadStatus.setBytesRead(bytesRead);
uploadStatus.setContentLength(contentLength);
uploadStatus.setItems(items);
uploadStatus.setUseTime(System.currentTimeMillis()-uploadStatus.getStartTime());
uploadStatus.setPercent((int)(100*bytesRead/contentLength));
session.setAttribute("upload_status", uploadStatus);
}
}
3、实现MultiPartRequest接口，主要是让自己的监听事件监听上传
package com.cngrain.util;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.RequestContext;
import org.apache.commons.fileupload.disk.DiskFileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.struts2.StrutsConstants;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.struts2.dispatcher.multipart.MultiPartRequest;
public class UploadCommonsMultipartResolver implements MultiPartRequest {
static final Logger LOG = LoggerFactory.getLogger(MultiPartRequest.class);
// maps parameter name -> List of FileItem objects
protected Map> files = new HashMap>();
// maps parameter name -> List of param values
protected Map> params = new HashMap>();
// any errors while processing this request
protected List errors = new ArrayList();
protected long maxSize;
@Inject(StrutsConstants.STRUTS_MULTIPART_MAXSIZE)
public void setMaxSize(String maxSize) {
this.maxSize = Long.parseLong(maxSize);
}
/**
* Creates a new request wrapper to handle multi-part data using methods
* adapted from Jason Pell's multipart classes (see class description).
*
* @param saveDir
* the directory to save off the file
* @param request
* the request containing the multipart
* @throws java.io.IOException
* is thrown if encoding fails.
*/
public void parse(HttpServletRequest request, String saveDir) throws IOException {
try {
processUpload(request, saveDir);
} catch (FileUploadException e) {
LOG.warn("Unable to parse request", e);
errors.add(e.getMessage());
}
}
private void processUpload(HttpServletRequest request, String saveDir)
throws FileUploadException, UnsupportedEncodingException {
for (FileItem item : parseRequest(request, saveDir)) {
if (LOG.isDebugEnabled()) {
LOG.debug("Found item " + item.getFieldName());
}
if (item.isFormField()) {
processNormalFormField(item, request.getCharacterEncoding());
} else {
processFileField(item);
}
}
}
private void processFileField(FileItem item) {
LOG.debug("Item is a file upload");
// Skip file uploads that don't have a file name - meaning that no file
// was selected.
if (item.getName() == null || item.getName().trim().length() < 1) {
LOG.debug("No file has been uploaded for the field: " + item.getFieldName());
return;
}
List values;
if (files.get(item.getFieldName()) != null) {
values = files.get(item.getFieldName());
} else {
values = new ArrayList();
}
values.add(item);
files.put(item.getFieldName(), values);
}
private void processNormalFormField(FileItem item, String charset) throws UnsupportedEncodingException {
LOG.debug("Item is a normal form field");
List values;
if (params.get(item.getFieldName()) != null) {
values = params.get(item.getFieldName());
} else {
values = new ArrayList();
}
// note: see http://jira.opensymphony.com/browse/WW-633
// basically, in some cases the charset may be null, so
// we're just going to try to "other" method (no idea if this
// will work)
if (charset != null) {
values.add(item.getString(charset));
} else {
values.add(item.getString());
}
params.put(item.getFieldName(), values);
}
private List parseRequest(HttpServletRequest servletRequest, String saveDir) throws FileUploadException {
DiskFileItemFactory fac = createDiskFileItemFactory(saveDir);
ServletFileUpload upload = new ServletFileUpload(fac);
upload.setSizeMax(maxSize);
/* 自己新建监听器 */
UploadListener progressListener = new UploadListener(servletRequest.getSession());
upload.setProgressListener(progressListener);// 添加自己的监听器
return upload.parseRequest(createRequestContext(servletRequest));
}
private DiskFileItemFactory createDiskFileItemFactory(String saveDir) {
DiskFileItemFactory fac = new DiskFileItemFactory();
// Make sure that the data is written to file
fac.setSizeThreshold(0);
if (saveDir != null) {
fac.setRepository(new File(saveDir));
}
return fac;
}
/*
* (non-Javadoc)
*
* @see org.apache.struts2.dispatcher.multipart.MultiPartRequest#
* getFileParameterNames()
*/
public Enumeration getFileParameterNames() {
return Collections.enumeration(files.keySet());
}
/*
* (non-Javadoc)
*
* @see
* org.apache.struts2.dispatcher.multipart.MultiPartRequest#getContentType(
* java.lang.String)
*/
public String[] getContentType(String fieldName) {
List items = files.get(fieldName);
if (items == null) {
return null;
}
List contentTypes = new ArrayList(items.size());
for (FileItem fileItem : items) {
contentTypes.add(fileItem.getContentType());
}
return contentTypes.toArray(new String[contentTypes.size()]);
}
/*
* (non-Javadoc)
*
* @see
* org.apache.struts2.dispatcher.multipart.MultiPartRequest#getFile(java.
* lang.String)
*/
public File[] getFile(String fieldName) {
List items = files.get(fieldName);
if (items == null) {
return null;
}
List fileList = new ArrayList(items.size());
for (FileItem fileItem : items) {
File storeLocation = ((DiskFileItem) fileItem).getStoreLocation();
if (fileItem.isInMemory() && storeLocation != null && !storeLocation.exists()) {
try {
storeLocation.createNewFile();
} catch (IOException e) {
if (LOG.isErrorEnabled()) {
LOG.error("Cannot write uploaded empty file to disk: " + storeLocation.getAbsolutePath(), e);
}
}
}
fileList.add(storeLocation);
}
return fileList.toArray(new File[fileList.size()]);
}
/*
* (non-Javadoc)
*
* @see
* org.apache.struts2.dispatcher.multipart.MultiPartRequest#getFileNames(
* java.lang.String)
*/
public String[] getFileNames(String fieldName) {
List items = files.get(fieldName);
if (items == null) {
return null;
}
List fileNames = new ArrayList(items.size());
for (FileItem fileItem : items) {
fileNames.add(getCanonicalName(fileItem.getName()));
}
return fileNames.toArray(new String[fileNames.size()]);
}
/*
* (non-Javadoc)
*
* @see org.apache.struts2.dispatcher.multipart.MultiPartRequest#
* getFilesystemName(java.lang.String)
*/
public String[] getFilesystemName(String fieldName) {
List items = files.get(fieldName);
if (items == null) {
return null;
}
List fileNames = new ArrayList(items.size());
for (FileItem fileItem : items) {
fileNames.add(((DiskFileItem) fileItem).getStoreLocation().getName());
}
return fileNames.toArray(new String[fileNames.size()]);
}
/*
* (non-Javadoc)
*
* @see
* org.apache.struts2.dispatcher.multipart.MultiPartRequest#getParameter(
* java.lang.String)
*/
public String getParameter(String name) {
List v = params.get(name);
if (v != null && v.size() > 0) {
return v.get(0);
}
return null;
}
/*
* (non-Javadoc)
*
* @see org.apache.struts2.dispatcher.multipart.MultiPartRequest#
* getParameterNames()
*/
public Enumeration getParameterNames() {
return Collections.enumeration(params.keySet());
}
/*
* (non-Javadoc)
*
* @see org.apache.struts2.dispatcher.multipart.MultiPartRequest#
* getParameterValues(java.lang.String)
*/
public String[] getParameterValues(String name) {
List v = params.get(name);
if (v != null && v.size() > 0) {
return v.toArray(new String[v.size()]);
}
return null;
}
/*
* (non-Javadoc)
*
* @see org.apache.struts2.dispatcher.multipart.MultiPartRequest#getErrors()
*/
public List getErrors() {
return errors;
}
/**
* Returns the canonical name of the given file.
*
* @param filename
* the given file
* @return the canonical name of the given file
*/
private String getCanonicalName(String filename) {
int forwardSlash = filename.lastIndexOf("/");
int backwardSlash = filename.lastIndexOf("\\");
if (forwardSlash != -1 && forwardSlash > backwardSlash) {
filename = filename.substring(forwardSlash + 1, filename.length());
} else if (backwardSlash != -1 && backwardSlash >= forwardSlash) {
filename = filename.substring(backwardSlash + 1, filename.length());
}
return filename;
}
/**
* Creates a RequestContext needed by Jakarta Commons Upload.
*
* @param req
* the request.
* @return a new request context.
*/
private RequestContext createRequestContext(final HttpServletRequest req) {
return new RequestContext() {
public String getCharacterEncoding() {
return req.getCharacterEncoding();
}
public String getContentType() {
return req.getContentType();
}
public int getContentLength() {
return req.getContentLength();
}
public InputStream getInputStream() throws IOException {
InputStream in = req.getInputStream();
if (in == null) {
throw new IOException("Missing content in the request");
}
return req.getInputStream();
}
};
}
@Override
public void cleanUp() {
// TODO Auto-generated method stub
}
}
4、.配置struts.xml
5、编写action获取上传信息
@Action(value = "getStatus", results = { @Result(name = SUCCESS, type = "json" ) })
public String getStatus(){
uploadStatus = (UploadStatus)request.getSession().getAttribute("upload_status");
return SUCCESS;
}