struts2实现文件上传显示进度条效果

一. struts2读取进度原理分析(作为草稿存了好久，刚刚发布出来......)

1.　在strut2中控制文件上传信息的类是实现MultiPartRequest接口的JakartaMultiPartRequest

其实第一次看到源文件时我打了个退堂鼓，因为觉得内容太长了，不想看。冷静下来将思路理顺，将分开的各个方法还原到一个方方中中，发现还是很好理解的：

@Override
 public void parse(HttpServletRequest request, String saveDir)
   throws IOException {
  setLocale(request);
　　　 　//规定了File文件的格式（如文件名必须是xxFileName，文件类型xxContentType），并定义了File的保存路径　　　　             DiskFileItemFactory factory = new DiskFileItemFactory(); 
  ServletFileUpload upload = new ServletFileUpload(factory);//处理文件上传的servlet
  upload.setProgressListener(new FileUploadProgressListener(request)); //为文件上传添加监听  factory.setSizeThreshold(0); //if (saveDir != null
   factory.setRepository(new File(saveDir));//临时路径
  }
  try {
   upload.setSizeMax(maxSize);
   List items = upload.parseRequest(createRequestContext(request)); //获取所有请求
   for (Object obItem : items) {
    FileItem item = (FileItem) obItem; //获取每个请求的文件
    if (LOG.isDebugEnabled()) {
     LOG.debug("Found item" + item.getFieldName());
    }
    if (item.isFormField()) { //普通表单提交
     LOG.debug("Item is a normal form field");
     List<String> values;
     if (params.get(item.getFieldName()) != null) {
      values = params.get(item.getFieldName());
     } else {
      values = new ArrayList<String>();
     }
     String charset = request.getCharacterEncoding();
     if (charset != null) {
      values.add(item.getString(charset));
     } else {
      values.add(item.getString());
     }
     params.put(item.getFieldName(), values);
    } else { //文件上传请求
     LOG.debug("Item is a file upload");
     if (item.getName() == null
       || item.getName().trim().length() <= 0) {
      LOG.debug("No file has been uploded for the filed:"
        + item.getFieldName());
      continue;
     }

     List<FileItem> values;
     if (files.get(item.getFieldName()) != null) {
      values = files.get(item.getFieldName());
     } else {
      values = new ArrayList<FileItem>();
     }
     values.add(item);
     files.put(item.getFieldName(), values);
    }
   }

  } catch (FileUploadBase.SizeLimitExceededException e) {
   System.out.println("错误1：" + e);
   if (LOG.isWarnEnabled()) {
    LOG.warn("Request exceeded size limit!", e);
   }
   String errorMessage = buildErrorMessage(e, new Object[]{e.getPermittedSize(), e.getActualSize()});
   if (!errors.contains(errorMessage)) {
    errors.add(errorMessage);
   }
  } catch (Exception e) {
   System.out.println("错误1：" + e);
   if (LOG.isWarnEnabled()) {
    LOG.warn("Unable to parse request", e);
   }
   String errorMessage = buildErrorMessage(e, new Object[]{});
   if (!errors.contains(errorMessage)) {
    errors.add(errorMessage);
   }
  }
 }

2.  文件上传监听文件FileUploadProgressListener.java

public class FileUploadProgressListener implements ProgressListener {
　　private final HttpSession session;
　　private final DecimalFormat format = new DecimalFormat("#00.0");

　　public FileUploadProgressListener(HttpServletRequest request) {
　　　　session = request.getSession();
　　　　FileUploadStatus status = new FileUploadStatus();
　　　　session.setAttribute("uploadStatus", status);
　　}

　　@Override
　　public void update(long pBytesRead, long pContentLength, int pItems) {
　　　　FileUploadStatus uploadStatus = (FileUploadStatus) session.getAttribute("uploadStatus");
　　　　Double uploadRate = (double) (pBytesRead * 100 / pContentLength);
　　　　uploadStatus.setUploadRate(Double.valueOf(format.format(uploadRate)));
　　　　uploadStatus.setReadedBytes(pBytesRead / 1024);
　　　　uploadStatus.setTotalBytes(pContentLength / 1024);
　　　　uploadStatus.setCurrentItems(pItems);
　　}
}

3. 添加状态文件：FileUploadStatus.java

public class FileUploadStatus {
 private Double uploadRate = 0.0;
 private Long readedBytes = 0L;
 private Long totalBytes = 0L;
 private int currentItems = 0;
 private Long uploadSpeed = 0L;
 private Long startTime = System.currentTimeMillis();
 private Long readedTimes = 0L;
 private Long totalTimes = 0L;
 // "-1" 错误 "0" 正常 "1" 完成
 private String error = "0";

 ...
  setter getter方法
 ...  
}

4. Action类（如果是多文件上传，则将File   FileName   ContentType定义成数组形式即可）

/**
 * 利用io流上传文件
 */
public class FileStreamUploadAction extends ActionSupport {
 /**
  * serialVersionUID作用： ---相当于类的身份证。 序列化时为了保持版本的兼容性，即在版本升级时反序列化仍保持对象的唯一性。
  * 有两种生成方式： 一个是默认的1L，比如：private static final long serialVersionUID = 1L;
  * 一个是根据类名、接口名、成员方法及属性等来生成一个64位的哈希字段，比如： private static final long
  * serialVersionUID = xxxxL;
  */
 private static final long serialVersionUID = 1L;
 private File image;
 private String imageFileName;
 private String imageContentType;
 private String message;
 public String uploadFile() {
  FileInputStream in = null;
  FileOutputStream out = null;
  System.out.println("文件名：" + imageFileName);
  try {
   this.setNewFileName(imageFileName);
   String realPath = ServletActionContext.getServletContext()
     .getRealPath("/file");
   File filePath = new File(realPath);
   if (!filePath.exists()) { // 如果保存的路径不存在则创建
    filePath.mkdir();
   }
   if (image == null) {
    message = "上传文件为空";
    System.out.println(message);
   } else {
    File saveFile = new File(filePath, this.getNewFileName());
    out = new FileOutputStream(saveFile);
   }
   in = new FileInputStream(image);
   byte[] byt = new byte[1024];
   int length = 0;
   while ((length = in.read(byt)) > 0) {
    out.write(byt, 0, length);
    out.flush();
   }
   message = "上传成功";
   System.out.println(message);
  } catch (FileNotFoundException e) {
   message = "找不到文件！";
   e.printStackTrace();
  } catch (IOException e) {
   message = "文件读取失败！";
   e.printStackTrace();
  } finally {
   closeStream(in, out);
  }
  return "uploadSucc";
 }
 public void closeStream(FileInputStream in, FileOutputStream out) {
  try {
   if (in != null) {
    in.close();
   }
   if (out != null) {
    out.close();
   }
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
  ...
  setter() getter()
  ...  
}

获取进度的Action

public class FileProgressAction extends ActionSupport {
　　private static final long serialVersionUID = 1L;
　　private FileUploadStatus uploadStatus;

　　public String uploadPercent() {
　　　　HttpSession session = ServletActionContext.getRequest().getSession();
　　　　this.uploadStatus = (FileUploadStatus) session.getAttribute("uploadStatus");
　　　　if (uploadStatus == null) {
　　　　　　System.out.println("action is null");
　　　　　　uploadStatus = new FileUploadStatus();
　　　　　　uploadStatus.setCurrentItems(0);
　　　　}
　　　　return "getPercent";
　　}

　　public FileUploadStatus getUploadStatus() {
　　　　return uploadStatus;
　　}

　　public void setUploadStatus(FileUploadStatus uploadStatus) {
　　　　this.uploadStatus = uploadStatus;
　　}
}

5.struts.xml中