利用Servlet使用数据流在jsp页面中显示硬盘中的图片 - 宋建勇 - ITeye博客
博客分类：
ShowImageFromDiskServlet.java代码如下：
.songjy.test.
import java.io.BufferedInputS
import java.io.BufferedOutputS
import java.io.F
import java.io.FileInputS
import java.io.IOE
import javax.servlet.ServletC
import javax.servlet.ServletE
import javax.servlet.http.HttpS
import javax.servlet.http.HttpServletR
import javax.servlet.http.HttpServletR
import mons.logging.L
import mons.logging.LogF
public class ShowImageFromDiskServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final Log log = LogFactory
.getLog(ShowImageFromDiskServlet.class);
String imageP
public ShowImageFromDiskServlet() {
public void init(ServletConfig config) throws ServletException {
imagePath = config.getInitParameter("imagePath");
("图片路径：" + imagePath);
protected void service(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(
response.getOutputStream());
File file = new File(imagePath);
BufferedInputStream bufferedInputStream = new BufferedInputStream(
new FileInputStream(file));
byte[] buffer = new byte[1024];
for(int len=0;(len=bufferedInputStream.read(buffer))&0;){
bufferedOutputStream.write(buffer, 0, len);
//bufferedOutputStream.flush();//关闭时会自动刷新，无需显示调用，否则必须显示调用
bufferedOutputStream.close();
bufferedInputStream.close();
/*private byte[] readStream(InputStream in) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int data = -1;
while ((data = in.read()) != -1) {
baos.write(data);
return baos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
* 通过url请求返回图像的字节流
@RequestMapping("icon/{cateogry}")
public void getIcon(@PathVariable("cateogry") String cateogry, HttpServletRequest request,
HttpServletResponse response) throws IOException {
if (StringUtils.isEmpty(cateogry)) {
cateogry = "";
String fileName = request.getSession().getServletContext().getRealPath("/") + "resource\\icons\\auth\\"
+ cateogry.toUpperCase().trim() + ".png";
File file = new File(fileName);
// 判断文件是否存在如果不存在就返回默认图标
if (!(file.exists() && file.canRead())) {
file = new File(request.getSession().getServletContext().getRealPath("/") + "resource/icons/auth/root.png");
FileInputStream inputStream = new FileInputStream(file);
byte[] data = new byte[(int) file.length()];
int length = inputStream.read(data);
inputStream.close();
response.setContentType("image/png");
OutputStream stream = response.getOutputStream();
stream.write(data);
stream.flush();
stream.close();
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宋建勇 写道 写道&!-- 文件拷贝时 ...
写道&!-- 文件拷贝时的编码 -- ...17:14 提问
jsp+servlet中servlet怎么获取值的问题
jsp中是这样的
servelt怎么获取这些值
按赞数排序
用getParameter获取
最后循环每行数据就行
楼主你好，你这个后台应该是获取到List数据，或者是ajax类型的json。如果是list，那你jsp中就用el表达式去循环打印出来；
如果是ajax的json，那你就在js中对获取到的data循环一下拼接到html中
你可以编写一个实体类，在servlet中调用对象，
但是JSP页面中的控件名一定要写作实体类.加控件名，然后在servelet中就可以获取了，绝对一一对应
正常来说用户列表是从后台数据库获取的数据，如果是修改和删除操作把id提交给后台就可以了，如果是增加的话要用表单，servlet中getrequestparam，对应前台的name字段
首先要为表单设置action以及method属性，然后再相对应的servlet中用getparameter便可以获得
其他相似问题servlet中session简介和使用例子
字体：[ ] 类型：转载 时间：
在servlet中,session是封装在javax.servlet.http.HttpSession这个接口中的，这个接口是构建在cookie或者URL重写的基础上,要得到一个HttpSession的实例，就可以通过HttpServletRequest的getSession()方法来获得
HttpServletRequest有两个重载的getSession()方法，一个接受一个boolean的类型的值，另一个不带任何参数，getSession()方法和getSession(true)方法功能一样，就是如果对应的客户端已经产生过一个session，那么就会返回这个旧的session，否则，这个方法将会产生一个session ID并且和对应的客户端绑定在一起，而如果getSession(false)表示如果对应的客户端已经有对应的session，那么返回这个旧的session，否则不会产生新的session。可以使用HttpSession对象上的isNow()方法来判定这个session是否为新建的
HttpSession常用方法
public void setAttribute(String name,Object value)将value对象以name名称绑定到会话public object getAttribute(String name)取得name的属性值，如果属性不存在则返回nullpublic void removeAttribute(String name)从会话中删除name属性，如果不存在不会执行，也不会抛处错误.public Enumeration getAttributeNames()返回和会话有关的枚举值public void invalidate()使会话失效，同时删除属性对象public Boolean isNew()用于检测当前客户是否为新的会话public long getCreationTime()返回会话创建时间public long getLastAccessedTime()返回在会话时间内web容器接收到客户最后发出的请求的时间public int getMaxInactiveInterval()返回在会话期间内客户请求的最长时间为秒public void setMaxInactiveInterval(int seconds)允许客户客户请求的最长时间ServletContext getServletContext()返回当前会话的上下文环境，ServletContext对象可以使Servlet与web容器进行通信public String getId()返回会话期间的识别号
一个保存信息到session的简单例子
sessionlogin.html 代码如下:
&meta name="keywords" content="keyword1,keyword2,keyword3" /&&meta name="description" content="this is my page" /&&meta name="content-type" content="text/ charset=UTF-8" /&&&!--&&& &link rel="stylesheet" type="text/css" href="./styles.css"&--&&/pre&&form action="servlet/saveinfo" method="post"&&用户名:&&input type="text" name="username" /& &input type="submit" /&&密码:&&input type="password" name="userpasswd" /&&&/form&&pre&&/pre&&/div&&div&
代码如下:package chap03;import java.io.IOEimport java.io.PrintWimport javax.servlet.ServletEimport javax.servlet.http.HttpSimport javax.servlet.http.HttpServletRimport javax.servlet.http.HttpServletRimport javax.servlet.http.HttpSpublic class saveinfo extends HttpServlet {/**&* Constructor of the object.&*/&public saveinfo() {&super();&}/**&* Destruction of the servlet.&*/&public void destroy() {&super.destroy(); // Just puts "destroy" string in log&// Put your code here&}/**&* The doGet method of the servlet.&*&* This method is called when a form has its tag value method equals to get.&*&* @param request the request send by the client to the server&* @param response the response send by the server to the client&* @throws ServletException if an error occurred&* @throws IOException if an error occurred&*/&public void doGet(HttpServletRequest request, HttpServletResponse response)&throws ServletException, IOException {&//如果用户输入过了用户名 则将其放在session中&if(request.getParameter("username")!=null);&{&HttpSession session = request.getSession();&session.setAttribute("username",request.getParameter("username"));&}&response.setContentType("text/charset=GBK");&PrintWriter out = response.getWriter();&out.println("session已经创建");&out.println("");&out.println("跳转到其他&a&页面&/a&");&}/**&* The doPost method of the servlet.&*&* This method is called when a form has its tag value method equals to post.&*&* @param request the request send by the client to the server&* @param response the response send by the server to the client&* @throws ServletException if an error occurred&* @throws IOException if an error occurred&*/&public void doPost(HttpServletRequest request, HttpServletResponse response)&throws ServletException, IOException {&doGet(request,response);&}/**&* Initialization of the servlet.&*&* @throws ServletException if an error occurs&*/&public void init() throws ServletException {&// Put your code here&}}&/pre&&/div&&div&
代码如下:package chap03;import java.io.IOEimport java.io.PrintWimport javax.servlet.ServletEimport javax.servlet.http.HttpSimport javax.servlet.http.HttpServletRimport javax.servlet.http.HttpServletRimport javax.servlet.http.HttpSpublic class getsession extends HttpServlet {/**&* Constructor of the object.&*/&public getsession() {&super();&}/**&* Destruction of the servlet.&*/&public void destroy() {&super.destroy(); // Just puts "destroy" string in log&// Put your code here&}/**&* The doGet method of the servlet.&*&* This method is called when a form has its tag value method equals to get.&*&* @param request the request send by the client to the server&* @param response the response send by the server to the client&* @throws ServletException if an error occurred&* @throws IOException if an error occurred&*/&public void doGet(HttpServletRequest request, HttpServletResponse response)&throws ServletException, IOException {response.setContentType("text/charset=GBK");&PrintWriter out = response.getWriter();&String username = "";&//此处不是创建session 而是去取已经创建的session&HttpSession session = request.getSession();&//如果已经取到，说明已经登录&if(session!=null)&{&username = (String)session.getAttribute("username");&out.println("获得创建的Session");&out.println("");&out.println("登录名:"+username);&}&else&{&response.sendRedirect("../sessionlogin.html");&}&}/**&* The doPost method of the servlet.&*&* This method is called when a form has its tag value method equals to post.&*&* @param request the request send by the client to the server&* @param response the response send by the server to the client&* @throws ServletException if an error occurred&* @throws IOException if an error occurred&*/&public void doPost(HttpServletRequest request, HttpServletResponse response)&throws ServletException, IOException {&doGet(request,response);&}/**&* Initialization of the servlet.&*&* @throws ServletException if an error occurs&*/&public void init() throws ServletException {&// Put your code here&}}&/pre&&/div&&div&&/div&&div&
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