在项目中，有时会将文本文件、图片以2进制的方式存入数据库，对应字段的类型为blob，一般在jsp页面操作字符串来处理图片、文本文件，如何将blob类型转换成String类型就成了关键。

public ActionForward getBulletin(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response) throws Exception {	buildAllBulletinType(request);	String id = request.getParameter("id");	String titleSub = "";	String title="";	String state="";	String bulletinDate = "";	List ll = BulletinServiceImpl.getInstance().selForId(id);        if(ll!=null && ll.size()>0)	{             Object [] obj = (Object [])ll.get(0);             if(obj[3]!=null)		{		Blob bo = (Blob)obj[3];		InputStream insm = bo.getBinaryStream();		byte [] fileContent = new byte [(int)bo.length()];		insm.read(fileContent);		String filetxt = new String (fileContent);                request.setAttribute("filetxt", filetxt);	        return  mapping.findForward("equityfile");        }    }