之前在做一个项目时用到了图片上传并立即展示到页面浏览，而且图片存放在硬盘上的一个文件夹中而非在工程与数据库中，这就会出现一个问题，如果不是在开发程序环境中访问图片页面，则会出现图片不能展示情况，原因很明显，就是外部无法访问到服务器硬盘上的图片。所以这时就需要用到i/o流读取图片并展示，以下是具体步骤：
1.图片展示页面showImg.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>i/o流读取图片</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <script src="local/communication/static/jquery.min.js" charset="utf-8"></script> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <div> <img id="viewImg2" src="local/communication/db/img.jsp?flag=zheng" style="height:90px;width:200px;" > </div> </body> </html>2.通过jsp页面服务读取图片，imp.jsp代码：
<%@ page language="java" import="java.util.*,java.util.Map.Entry,java.text.SimpleDateFormat,java.util.Date,net.sf.json.JSONArray,net.sf.json.JSONObject,java.net.URLEncoder,java.net.URLDecoder" pageEncoding="utf-8"%> <%@page import="java.io.FileInputStream"%> <%@page import="java.io.BufferedOutputStream"%> <%@page import="java.io.InputStream"%> <%@page import="java.io.BufferedInputStream"%> <%@page import="java.io.OutputStream,java.io.FileOutputStream,java.io.IOException,java.io.FileInputStream,java.io.PrintWriter," %> <% request.setCharacterEncoding("UTF-8"); response.setContentType("image/png"); response.setHeader("Content-Disposition","attachment;Filename=test.png"); BufferedOutputStream bos = null; InputStream fis = null; BufferedInputStream bis = null; String flag=request.getParameter("flag")==null?"":request.getParameter("flag"); try{ String tPath="D://img/11.jsp"; bos = new BufferedOutputStream(response.getOutputStream()); fis = new FileInputStream(tPath); bis = new BufferedInputStream(fis); byte[] buff = new byte[2048]; int bytesRead; while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) { bos.write(buff, 0, bytesRead); } bos.flush(); }catch(Exception e){ }finally{ if(bos!=null){ bos.close(); } if(bis!=null){ bis.close(); } if(fis!=null){ fis.close(); } } out.clear(); out = pageContext.pushBody(); %>
