1. 點選圖片觸發上傳的事件

2. 上傳圖片

3. 返回圖片路徑展示

具體程式碼為：

1. 在物件上繫結點選事件

<img src="" alt="點選上傳" id="faceImg" style="border: 1px solid; width: 50px; height: 50px; padding: 5px; cursor: pointer;" onclick="toUpload();" />

function toUpload() {
			jQuery('#oldFilePath').val(getImgPath()); 
			jQuery('#fileUpload').click();
		}
 

function getImgPath() {
			return jQuery('#faceImg').attr('src').replace(extApi.getWebRoot(), '');
		}

 <form id="formFile" method="post" enctype="multipart/form-data"  target="frameFile" >
				<input type="file" accept="image/*" id="fileUpload" name="fileUpload" class="input-file" onchange="uploadFile();">  
				<input type="hidden" value="" id="oldFilePath" name="oldFilePath"> 
		  </form>
 

function uploadFile() {
			var form = jQuery("#formFile");
			form.ajaxSubmit({
				url : 'upload_img_used.action',
				type : 'post',
				beforeSubmit : function() {
					layer.load();
				},
				success : function(data) {
					layer.closeAll('loading');
					jQuery('#faceImg').attr('src', extApi.getWebRoot() + data);
				}
			});
		}
 

public class FileUpload
{
	private static Logger logger = Logger.getLogger(FileUpload.class);

	/**
	 * 伺服器檔案上傳總資料夾名
	 */
	public static final String UPLOAD = "upload" + File.separator;

	/**
	 * 預設表單檔名
	 */
	public static final String INPUT = "fileUpload";

	/**
	 * 上傳檔案,隨機生成檔名,採用預設檔案表單name
	 * 
	 * @param request
	 * @param uploadFolder
	 *            上傳目標目錄
	 * @return
	 * @throws FrameworkException
	 */
	public static String upload(HttpServletRequest request, String uploadFolder)
			throws FrameworkException
	{
		return uploadFile(request, INPUT, uploadFolder, false, null);
	}
	/**
	 * 上傳檔案,隨機生成檔名
	 * 
	 * @param request
	 * @param imgInput
	 *            檔案表單name
	 * @param uploadFolder
	 *            上傳目標目錄
	 * @return
	 * @throws FrameworkException
	 */
	public static String upload(HttpServletRequest request, String imgInput, String uploadFolder)
			throws FrameworkException
	{
		return uploadFile(request, imgInput, uploadFolder, false, null);
	}

	/**
	 * 上傳檔案,檔名隨機生成,採用預設表單name, 刪除舊檔案
	 * 
	 * @param request
	 * @param uploadFolder
	 *            上傳目標路徑
	 * @param oldPath
	 *            舊檔案路徑
	 * @return
	 * @throws FrameworkException
	 */
	public static String uploadDelOld(HttpServletRequest request, String uploadFolder,
			String oldPath) throws FrameworkException
	{
		return uploadFile(request, INPUT, uploadFolder, false, oldPath);
	}
	/**
	 * 上傳檔案,檔名隨機生成,刪除舊檔案
	 * 
	 * @param request
	 * @param inputName
	 *            檔案表單name
	 * @param uploadFolder
	 *            上傳目標路徑
	 * @param oldPath
	 *            舊檔案路徑
	 * @return
	 * @throws FrameworkException
	 */
	public static String uploadDelOld(HttpServletRequest request, String inputName,
			String uploadFolder, String oldPath) throws FrameworkException
	{
		return uploadFile(request, inputName, uploadFolder, false, oldPath);
	}

	/**
	 * 上傳檔案,指定檔名,採取預設表單name
	 * 
	 * @param request
	 * @param uploadFolder
	 *            上傳資料夾
	 * @param fileName
	 *            檔名
	 * @return
	 * @throws FrameworkException
	 */
	public static String uploadHasName(HttpServletRequest request, String uploadFolder)
			throws FrameworkException
	{
		return uploadFile(request, INPUT, uploadFolder, true, null);
	}
	/**
	 * 上傳檔案,並指定檔名
	 * 
	 * @param request
	 * @param inputName
	 *            檔案表單name
	 * @param uploadFolder
	 *            上傳目錄
	 * @param fileName
	 *            檔名
	 * @return
	 * @throws FrameworkException
	 */
	public static String uploadHasName(HttpServletRequest request, String inputName,
			String uploadFolder) throws FrameworkException
	{
		return uploadFile(request, inputName, uploadFolder, true, null);
	}
	/**
	 * 上傳檔案,指定檔名稱,並刪除舊檔案
	 * 
	 * @param request
	 * @param inputName
	 *            檔案表單name
	 * @param uploadFolder
	 *            上傳目錄
	 * @param fileName
	 *            檔名
	 * @param oldPath
	 *            舊檔案路徑
	 * @return
	 * @throws FrameworkException
	 */
	public static String uploadHasName(HttpServletRequest request, String inputName,
			String uploadFolder, String oldPath) throws FrameworkException
	{
		return uploadFile(request, inputName, uploadFolder, true, oldPath);
	}

	/**
	 * 獲取表單中檔案資料內容
	 * 
	 * @param request
	 * @param inputName
	 *            檔案表單name
	 * @param uploadFolder
	 *            上傳目標目錄
	 * @param fileName
	 *            檔名
	 * @param oldPath
	 *            舊檔案路徑
	 * @return
	 * @throws FrameworkException
	 */
	private static String uploadFile(HttpServletRequest request, String inputName,
			String uploadFolder, boolean isHasName, String oldPath) throws FrameworkException
	{
		// 獲取上傳的資料內容
		MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
		CommonsMultipartFile file = (CommonsMultipartFile) multipartRequest.getFile(inputName);
		if (null == file)
		{
			return null;
		}
		return uploadFile(request, file, uploadFolder, isHasName, oldPath);
	}

	/**
	 * 將檔案資料存入伺服器
	 * 
	 * @param request
	 * @param file
	 *            檔案資料內容
	 * @param upLoadPath
	 *            上傳目標路徑
	 * @param fileName
	 *            檔名
	 * @param oldPath
	 *            舊檔案路徑
	 * @return
	 * @throws FrameworkException
	 */
	private static String uploadFile(HttpServletRequest request, CommonsMultipartFile file,
			String upLoadPath, boolean isHasName, String oldPath) throws FrameworkException
	{
		try
		{
			// 拼湊檔案儲存到服務端本地的路徑
			String strRoot = getRootUrl(request);
			// 若存在舊路徑且檔案存在,則刪除舊檔案
			if (!StringUtils.isNullOrEmpty(oldPath) && FileUtils.isExist(strRoot + oldPath))
			{
				delImg(request, oldPath);
			}
			// 獲取檔名
			String fileName = file.getOriginalFilename();
			// 不保留檔名則隨機生成檔名
			if (!isHasName)
			{
				// 獲取字尾
				String suffix = FileUtils.getFileExt(file.getOriginalFilename());
				fileName = EnvUtils.getHashId();
				// 與字尾拼接
				fileName += suffix;
			}
			logger.info("檔名: " + fileName);
			// 獲取路徑
			String filePath = getFilePath(strRoot, upLoadPath, fileName);
			// 若檔案存在,則刪除
			if (FileUtils.isExist(filePath))
			{
				FileUtils.delete(filePath);
			}
			// 上傳檔案
			FileUtils.save(file.getInputStream(), filePath);
			// 獲取返回路徑
			filePath = filePath.replace(strRoot, ""); // 清除伺服器根目錄
			filePath = filePath.replaceAll("\\\\", "/"); // 瀏覽器和linux中路徑使用反斜槓.
			logger.info("檔案已上傳: " + filePath);
			return filePath;
		}
		catch (Exception e)
		{
			logger.error("上傳圖片失敗", e);
			throw new FrameworkException("上傳檔案失敗", e);
		}
	}

	/**
	 * 獲取當前伺服器根路徑
	 * 
	 * @param request
	 * @return
	 */
	private static String getRootUrl(HttpServletRequest request)
	{
		return request.getSession().getServletContext().getRealPath("/");
	}

	/**
	 * 轉化出一個資料夾名
	 * 
	 * @param folderName
	 * @return
	 */
	public static String toFolder(String folderName)
	{
		return folderName + File.separator;
	}

	/**
	 * 拼接檔案上傳路徑
	 * 
	 * @param strRoot
	 *            伺服器根路徑
	 * @param upLoadPath
	 *            上傳路徑
	 * @param fileName
	 *            檔名
	 * @return
	 */
	private static String getFilePath(String strRoot, String upLoadPath, String fileName)
	{
		StringBuffer path = new StringBuffer(strRoot);
		path.append(UPLOAD);
		path.append(upLoadPath);
		path.append(fileName);
		return path.toString();
	}
	/**
	 * @param path
	 * @param request
	 * @throws FrameworkException
	 */
	public static void delImg(HttpServletRequest request, String path) throws FrameworkException
	{
		String strRoot = getRootUrl(request);
		FileUtils.delete(strRoot + path);
		logger.info("刪除舊檔案: " + strRoot + path);
	}
}