文件上传工具类

public class UploadUtils {
   /**
    * 表单字段常量
    */
   public static final String FORM_FIELDS = "form_fields";
   /**
    * 文件域常量
    */
   public static final String FILE_FIELDS = "file_fields";

   // 最大文件大小
   private long maxSize = 1000000;
   // 定义允许上传的文件扩展名
   private Map<String, String> extMap = new HashMap<String, String>();
   // 文件保存目录相对路径
   private String basePath = "upload";
   // 文件的目录名
   private String dirName = "images";
   // 上传临时路径
   private static final String TEMP_PATH = "/temp";
   private String tempPath = basePath + TEMP_PATH;
   // 若不指定则文件名默认为 yyyyMMddHHmmss_xyz
   private String fileName;

   // 文件保存目录路径
   private String savePath;
   // 文件保存目录url
   private String saveUrl;
   // 文件最终的url包括文件名
   private String fileUrl;

   public UploadUtils() {
      // 其中images,flashs,medias,files,对应文件夹名称,对应dirName
      // key文件夹名称
      // value该文件夹内可以上传文件的后缀名
      extMap.put("images", "gif,jpg,jpeg,png,bmp");
      extMap.put("flashs", "swf,flv");
      extMap.put("medias", "swf,flv,mp3,wav,wma,wmv,mid,avi,mpg,asf,rm,rmvb");
      extMap.put("files", "doc,docx,xls,xlsx,ppt,htm,html,txt,zip,rar,gz,bz2");
   }

   /**
    * 文件上传
    * 
    * @param request
    * @return infos info[0] 验证文件域返回错误信息 info[1] 上传文件错误信息 info[2] savePath info[3] saveUrl info[4] fileUrl
    */
   @SuppressWarnings("unchecked")
   public String[] uploadFile(HttpServletRequest request) {
      String[] infos = new String[5];
      // 验证
      infos[0] = this.validateFields(request);
      // 初始化表单元素
      Map<String, Object> fieldsMap = new HashMap<String, Object>();
      if (infos[0].equals("true")) {
         fieldsMap = this.initFields(request);
      }
      // 上传
      List<FileItem> fiList = (List<FileItem>) fieldsMap.get(UploadUtils.FILE_FIELDS);
      if (fiList != null) {
         for (FileItem item : fiList) {
            infos[1] = this.saveFile(item);
         }
         infos[2] = savePath;
         infos[3] = saveUrl;
         infos[4] = fileUrl;
      }
      return infos;
   }

   /**
    * 上传验证,并初始化文件目录
    * 
    * @param request
    */
   private String validateFields(HttpServletRequest request) {
      String errorInfo = "true";
      // boolean errorFlag = true;
      // 获取内容类型
      String contentType = request.getContentType();
      int contentLength = request.getContentLength();
      // 文件保存目录路径
      savePath = request.getSession().getServletContext().getRealPath("/") + basePath + "/";
      // 文件保存目录URL
      saveUrl = request.getContextPath() + "/" + basePath + "/";
      File uploadDir = new File(savePath);
      if (contentType == null || !contentType.startsWith("multipart")) {
         // TODO
         System.out.println("请求不包含multipart/form-data流");
         errorInfo = "请求不包含multipart/form-data流";
      } else if (maxSize < contentLength) {
         // TODO
         System.out.println("上传文件大小超出文件最大大小");
         errorInfo = "上传文件大小超出文件最大大小[" + maxSize + "]";
      } else if (!ServletFileUpload.isMultipartContent(request)) {
         // TODO
         errorInfo = "请选择文件";
      } else if (!uploadDir.isDirectory()) {// 检查目录
         // TODO
         errorInfo = "上传目录[" + savePath + "]不存在";
      } else if (!uploadDir.canWrite()) {
         // TODO
         errorInfo = "上传目录[" + savePath + "]没有写权限";
      } else if (!extMap.containsKey(dirName)) {
         // TODO
         errorInfo = "目录名不正确";
      } else {
         // .../basePath/dirName/
         // 创建文件夹
         savePath += dirName + "/";
         saveUrl += dirName + "/";
         File saveDirFile = new File(savePath);
         if (!saveDirFile.exists()) {
            saveDirFile.mkdirs();
         }
         // .../basePath/dirName/yyyyMMdd/
         SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
         String ymd = sdf.format(new Date());
         savePath += ymd + "/";
         saveUrl += ymd + "/";
         File dirFile = new File(savePath);
         if (!dirFile.exists()) {
            dirFile.mkdirs();
         }

         // 获取上传临时路径
         tempPath = request.getSession().getServletContext().getRealPath("/") + tempPath + "/";
         File file = new File(tempPath);
         if (!file.exists()) {
            file.mkdirs();
         }
      }

      return errorInfo;
   }

   /**
    * 处理上传内容
    * 
    * @param request
    * @param maxSize
    * @return
    */
// @SuppressWarnings("unchecked")
   private Map<String, Object> initFields(HttpServletRequest request) {

      // 存储表单字段和非表单字段
      Map<String, Object> map = new HashMap<String, Object>();

      // 第一步：判断request
      boolean isMultipart = ServletFileUpload.isMultipartContent(request);
      // 第二步：解析request
      if (isMultipart) {
         // Create a factory for disk-based file items
         DiskFileItemFactory factory = new DiskFileItemFactory();

         // 阀值,超过这个值才会写到临时目录,否则在内存中
         factory.setSizeThreshold(1024 * 1024 * 10);
         factory.setRepository(new File(tempPath));

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

         upload.setHeaderEncoding("UTF-8");

         // 最大上传限制
         upload.setSizeMax(maxSize);

         /* FileItem */
         List<FileItem> items = null;
         // Parse the request
         try {
            items = upload.parseRequest(request);
         } catch (FileUploadException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         }

         // 第3步：处理uploaded items
         if (items != null && items.size() > 0) {
            Iterator<FileItem> iter = items.iterator();
            // 文件域对象
            List<FileItem> list = new ArrayList<FileItem>();
            // 表单字段
            Map<String, String> fields = new HashMap<String, String>();
            while (iter.hasNext()) {
               FileItem item = iter.next();
               // 处理所有表单元素和文件域表单元素
               if (item.isFormField()) { // 表单元素
                  String name = item.getFieldName();
                  String value = item.getString();
                  fields.put(name, value);
               } else { // 文件域表单元素
list.add(item);               }            }            


map.put(FORM_FIELDS, fields);            
map.put(FILE_FIELDS, list);         }      }      


return map;   }   


/**
    * 保存文件
* 
    * @param obj
*            要上传的文件域
* @param file
* @return
    */
private String saveFile(FileItem item) {      
String error = "true";      
String fileName = item.getName();      
String fileExt = fileName.substring(fileName.lastIndexOf(".") + 1).toLowerCase();      

if (item.getSize() > maxSize) { // 检查文件大小
// TODO
         error = "上传文件大小超过限制";      } 
else if (!Arrays.<String> asList(extMap.get(dirName).split(",")).contains(fileExt)) {// 检查扩展名
         error = "上传文件扩展名是不允许的扩展名。
只允许" + extMap.get(dirName) + "格式。";      } 
else {         
String newFileName;         
if ("".equals(fileName.trim())) {            
SimpleDateFormat df = new SimpleDateFormat("yyyyMMddHHmmss");            
newFileName = df.format(new Date()) + "_" + new Random().nextInt(1000) + "." + fileExt;         } 
else {            
newFileName = fileName + "." + fileExt;         }         

// .../basePath/dirName/yyyyMMdd/yyyyMMddHHmmss_xxx.xxx
fileUrl = saveUrl + newFileName;         
try {            
File uploadedFile = new File(savePath, newFileName);            item.write(

uploadedFile);            

/*
             * FileOutputStream fos = new FileOutputStream(uploadFile); // 文件全在内存中 if (item.isInMemory()) { fos.write(item.get()); } else { InputStream is = item.getInputStream(); byte[] buffer =
             * new byte[1024]; int len; while ((len = is.read(buffer)) > 0) { fos.write(buffer, 0, len); } is.close(); } fos.close(); item.delete();
             */
         } catch (IOException e) {            e.printStackTrace();            

System.out.println("上传失败了！！！");         } 
catch (Exception e) {            e.printStackTrace();         }      }      



return error;   }   


/** **********************get/set方法********************************* */

public String getSavePath() {      
return savePath;   }   


public String getSaveUrl() {      
return saveUrl;   }   


public long getMaxSize() {      
return maxSize;   }   


public void setMaxSize(long maxSize) {      
this.maxSize = maxSize;   }   


public Map<String, String> getExtMap() {      
return extMap;   }   


public void setExtMap(Map<String, String> extMap) {      
this.extMap = extMap;   }   


public String getBasePath() {      
return basePath;   }   


public void setBasePath(String basePath) {      
this.basePath = basePath;      
tempPath = basePath + TEMP_PATH;   }   


public String getDirName() {      
return dirName;   }   


public void setDirName(String dirName) {      
this.dirName = dirName;   }   


public String getTempPath() {      
return tempPath;   }   


public void setTempPath(String tempPath) {      
this.tempPath = tempPath;   }   


public String getFileUrl() {      
return fileUrl;   }   


public String getFileName() {      
return fileName;   }   


public void setFileName(String fileName) {      
this.fileName = fileName;   }}