commons-fileupload实现上传 Upload.java

import java.io.File;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadBase;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

public class SlideUploadAction extends Action {

 @SuppressWarnings("unchecked")
 @Override
 public ActionForward execute(ActionMapping mapping, ActionForm form,
   HttpServletRequest request, HttpServletResponse response)
   throws Exception {
  String newName = request.getParameter("newName");
  String uploadPath = this.getServlet().getServletContext().getRealPath(
    "/upload/slide/"); // 上传文件的目录 
  // getRealPath 返回值在不同服务器上有的带反斜杠，有的不带
  if (!uploadPath.endsWith(File.separator)) {
   uploadPath += File.separator;
  }
  String tempPath = uploadPath + "temp/"; // 临时文件目录

  // 检查文件上传目录和临时目录是否存在，若不存在则创建目录。
  File uploadFile = new File(uploadPath);
  if (!uploadFile.exists()) {
   uploadFile.mkdirs();
  }
  File tempPathFile = new File(tempPath);
  if (!tempPathFile.exists()) {
   tempPathFile.mkdirs();
  }

  PrintWriter writer = response.getWriter();
  // OutputStream out = response.getOutputStream();
  boolean isError = false;
  String error = "";
  String msg = "";
  // Create a factory for disk-based file items
  DiskFileItemFactory factory = new DiskFileItemFactory();

  // Set factory constraints
  factory.setSizeThreshold(4096); // 设置缓冲区大小，这里是4kb
  factory.setRepository(tempPathFile);// 设置缓冲区目录

  // Create a new file upload handler
  ServletFileUpload upload = new ServletFileUpload(factory);

  // Set overall request size constraint
  upload.setSizeMax(2 * 1024 * 1024); // 设置最大文件尺寸，这里是4MB
  try {
   List items = upload.parseRequest(request);// 得到所有的文件
   System.out.println("----items:" + items.size());
   Iterator i = items.iterator();
   while (i.hasNext()) {
    FileItem fi = (FileItem) i.next();
    System.out.println("----fileSize:" + fi.getSize());

    String fileName = fi.getName();
    if (fileName.isEmpty()) {
     isError = true;
     error = "没有文件要上传！";
    } else if (!fileName.endsWith(".jpg")) {
     isError = true;
     error = "只能上传jpg格式的文件！";
    } else if (fi.getSize() > 2 * 1024 * 1024) {
     isError = true;
     error = "文件不能超过2M！";

     throw new Exception("文件超过大小");
    }
    if (!isError) {
     File fullFile = new File(newName);
     File savedFile = new File(uploadPath, fullFile.getName());
     fi.write(savedFile);
    }
   }
   System.out.print("upload succeed");
   msg = "上传完成！";
  } catch (FileUploadBase.SizeLimitExceededException e) {
   error = "文件超出大小限制！";
  } catch (FileUploadBase.IOFileUploadException e) {
   error = "传输错误，可能磁盘空间不足！";
  } catch (FileUploadBase.InvalidContentTypeException e) {
   error = "无效的请求类型，enctype != 'multipart/form-data'";
  } catch (Exception e) {
   // 可以跳转出错页面
   if (error.isEmpty()) {
    error = "出现未知错误，上传失败";
   }
   e.printStackTrace();
  }
  writer.println("{");
  writer.println("error: '" + error + "',");
  writer.println("msg: '" + msg + "'");
  writer.println("}");

  writer.flush();
  writer.close();
  return null;
 }

}