Javaweb崔希凡---Day11---Cookie和session
1 JSP概述
案例：演示jsp中java脚本的使用
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
JSP演示
JSP演示
<%
// Java语句
String s1 = "hello jsp";
// 不会输出到客户端，而是在服务器端的控制台打印
System.out.println(s1);
%>
输出变量：<%=s1 %>
输出int类型常量：<%=100 %>
输出String类型常量：<%="你好" %>
使用表达式输出常量是很傻的一件事，因为可以直接使用html即可，下面是输出上面的常量：
100
你好
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();//获取项目名
/*
http://localhost:8080/day11_1/
*/
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'index.jsp' starting page
This is my JSP page.
<%
int a = 10;
%>
<%
out.print(a++);
%>
<%=a %>
<%!
int a = 100;
public void fun1() {
System.out.println(a);
}
%>
<%
out.print(this.a++);
fun1();
%>
案例：演示jsp与servlet分工！
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'form.jsp' starting page
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'result.jsp' starting page
<%
Integer result = (Integer)request.getAttribute("result");
%>
<%=result %>
package cn.itcast.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class AServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 获取参数
String s1 = request.getParameter("num1");
String s2 = request.getParameter("num2");
// 转换成int类型
int num1 = Integer.parseInt(s1);
int num2 = Integer.parseInt(s2);
// 运算
int sum = num1 + num2;
// 把结果保存到request域中
request.setAttribute("result", sum);
// 转换到result.jsp
request.getRequestDispatcher("/jia/result.jsp").forward(request, response);
}
}
out.jsp
<%
//向客户端输出
out.print("你好！");
%>
out.jsp
<%
String s = "hello";
%>
<%
out.print(s);
%>
循环打印表格：
表格
序号
用户名
密码
<%
for(int i = 0; i < 10; i++) {
%>
<%=i+1 %>
user<%=i %>
<%=100 + 1 %>
<%
}
%>
4. jsp原理（理解）
a_jsp.java的_jspService()方法：
上述代码中标记的对象都是：
上述代码中末尾处…表示：
<%!
private String name;
public String hello() {
return "hello JSP!";
}
%>
5. jsp注释
会话跟踪技术
Cookie
1. Http协议与Cookie（了解）
2. Cookie的用途
3. JavaWeb中使用Cookie
1.5 Cookie第一例
AServlet.java ：
package cn.itcast.servlet;
import java.io.IOException;
import java.util.UUID;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 给客户端发送Cookie
* @author Administrator
*
*/
public class AServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
String id = UUID.randomUUID().toString();//生成一个随机字符串
Cookie cookie = new Cookie("id", id);//创建Cookie对象，指定名字和值
response.addCookie(cookie);//在响应中添加Cookie对象
response.getWriter().print("已经给你发送了ID");
}
}
BServlet.java ：
package cn.itcast.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 获取客户端请求中的Cookie
* @author Administrator
*
*/
public class BServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
Cookie[] cs = request.getCookies();//获取请求中的Cookie
if(cs != null) {//如果请求中存在Cookie
for(Cookie c : cs) {//遍历所有Cookie
if(c.getName().equals("id")) {//获取Cookie名字，如果Cookie名字是id
response.getWriter().print("您的ID是：" + c.getValue());//打印Cookie值
}
}
}
}
}
4. Cookie详解
Google查看Cookie：
AServlet.java ：
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
Cookie cookie = new Cookie("lasttime", new Date().toString());
cookie.setMaxAge(60 * 60);
response.addCookie(cookie);
Cookie[] cs = request.getCookies();
String s = "您是首次访问本站！";
if(cs != null) {
for(Cookie c : cs) {
if(c.getName().equals("lasttime")) {
s = "您上次的访问时间是：" + c.getValue();
}
}
}
response.getWriter().print(s);
}
3 Cookie的path
4 Cookie的domain
了解！！！
5 Cookie中保存中文
向客户端响应中添加Cookie：
String name = URLEncoder.encode("姓名", "UTF-8");
String value = URLEncoder.encode("张三", "UTF-8");
Cookie c = new Cookie(name, value);
c.setMaxAge(3600);
response.addCookie(c);
从客户端请求中获取Cookie ：
response.setContentType("text/html;charset=utf-8");
Cookie[] cs = request.getCookies();
if(cs != null) {
for(Cookie c : cs) {
String name = URLDecoder.decode(c.getName(), "UTF-8"); //把Cookie的name和value使用URL解码后再打印。
String value = URLDecoder.decode(c.getValue(), "UTF-8");
String s = name + ": " + value + "
";
response.getWriter().print(s);
}
}
6 显示曾经浏览过的商品
index.jsp
商品列表
ThinkPad
Lenovo
Apple
HP
SONY
ACER
DELL
您浏览过的商品：
<%
Cookie[] cs = request.getCookies();
if(cs != null) {
for(Cookie c : cs) {
if(c.getName().equals("goods")) {
out.print(c.getValue());
}
}
}
%>
GoodServlet
public class GoodServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String goodName = request.getParameter("name");
String goods = CookieUtils.getCookValue(request, "goods");
if(goods != null) {
String[] arr = goods.split(", ");
Set goodSet = new LinkedHashSet(Arrays.asList(arr));
goodSet.add(goodName);
goods = goodSet.toString();
goods = goods.substring(1, goods.length() - 1);
} else {
goods = goodName;
}
Cookie cookie = new Cookie("goods", goods);
cookie.setMaxAge(1 * 60 * 60 * 24);
response.addCookie(cookie);
response.sendRedirect("/day06_3/index.jsp");
}
}
CookieUtils
public class CookieUtils {
public static String getCookValue(HttpServletRequest request, String name) {
Cookie[] cs = request.getCookies();
if(cs == null) {
return null;
}
for(Cookie c : cs) {
if(c.getName().equals(name)) {
return c.getValue();
}
}
return null;
}
}
HttpSession
1 HttpSession概述
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'a.jsp' starting page
向session域保存数据
<%
session.setAttribute("aaa", "AAA");
%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'b.jsp' starting page
获取session中的数据
<%
String s = (String)session.getAttribute("aaa");
%>
<%=s %>
案例2：演示保存用户登录信息（精通）
login.jsp :
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'login.jsp' starting page
<%-- 本页面提供登录表单，还要显示错误信息 --%>
登录
<%
/*
读取名为uname的Cookie!
如果为空显示：""
如果不为空显示：Cookie的值
*/
String uname = "";
Cookie[] cs = request.getCookies();//获取请求中所有的cookie
if(cs != null) {// 如果存在cookie
for(Cookie c : cs) {//循环遍历所有的cookie
if("uname".equals(c.getName())) {//查找名为uname的cookie
uname = c.getValue();//获取这个cookie的值，给uname这个变量
}
}
}
%>
<%
String message = "";
String msg = (String)request.getAttribute("msg");//获取request域中的名为msg的属性
if(msg != null) {
message = msg;
}
%>
<%=message %>
LoginServlet.java :
package cn.itcast.servlet;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LoginServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* 1. 获取表单数据
*/
// 处理中文问题
request.setCharacterEncoding("utf-8");
// 获取
String username = request.getParameter("username");
String password = request.getParameter("password");
/*
* 2. 校验用户名和密码是否正确
*/
if(!"itcast".equalsIgnoreCase(username)) {//登录成功
/*
* 附加项：把用户名保存到cookie中，发送给客户端浏览器
* 当再次打开login.jsp时，login.jsp中会读取request中的cookie，把它显示到用户名文本框中
*/
Cookie cookie = new Cookie("uname", username);//创建Cookie
cookie.setMaxAge(60*60*24);//设置cookie命长为1天
response.addCookie(cookie);//保存cookie
/*
* 3. 如果成功
* > 保存用户信息到session中
* > 重定向到succ1.jsp
*/
HttpSession session = request.getSession();//获取session
session.setAttribute("username", username);//向session域中保存用户名
response.sendRedirect("/day11_3/session2/succ1.jsp");
} else {//登录失败
/*
* 4. 如果失败
* > 保存错误信息到request域中
* > 转发到login.jsp
*/
request.setAttribute("msg", "用户名或密码错误!");
RequestDispatcher qr = request.getRequestDispatcher("/session2/login.jsp");//得到转发器
qr.forward(request, response);//转发
}
}
}
succ1.jsp :
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'succ1.jsp' starting page
succ1
<%
String username = (String)session.getAttribute("username");
if(username == null) {
/*
1. 向request域中保存错误信息，转发到login.jsp
*/
request.setAttribute("msg", "您还没有登录，不要冒充领导！");
request.getRequestDispatcher("/session2/login.jsp").forward(request, response);
return;
}
%>
欢迎欢迎，热烈欢迎，欢迎<%=username %>领导指导工作！
succ2.jsp :
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'succ2.jsp' starting page
succ2
<%
String username = (String)session.getAttribute("username");
if(username == null) {
/*
1. 向request域中保存错误信息，转发到login.jsp
*/
request.setAttribute("msg", "您还没有登录，不要冒充领导！");
request.getRequestDispatcher("/session2/login.jsp").forward(request, response);
return;
}
%>
欢迎欢迎，热烈欢迎，欢迎<%=username %>领导指导工作！
5. HttpSession原理（理解）
web.xml ：
30
index.jsp ：
URL重写
主页
请求注意，在index.jsp后面使用的是分号，而不是问号，这是服务器对jsessionid这个参数的特殊要求。
主页
案例：一次性图片验证码
动态生成图片：
package cn.itcast.image;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import org.junit.Test;
/**
* 动态生成图片
* @author cxf
*
*/
public class Demo {
@Test
public void fun1() throws FileNotFoundException, IOException {
/*
* 1. 创建图片缓冲区
* 2. 设置其宽高
* 3. 得到这个图片的绘制环境（得到画笔）
* 4. 保存起来
*/
BufferedImage bi = new BufferedImage(70, 35, BufferedImage.TYPE_INT_RGB);
Graphics2D g = (Graphics2D)bi.getGraphics();//得到绘制环境
g.setColor(Color.WHITE);//把环境设置为白色
g.fillRect(0, 0, 70, 35);//填充矩形！填充矩形，从0,0点开始，宽70，高35，即整个图片，即为图片设置背景色
g.setColor(Color.RED);//把环境设置为红色
g.drawString("Hello", 2, 35-2);//向图片上写入字符串，其中2,2表示x,y轴的坐标
ImageIO.write(bi, "JPEG", new FileOutputStream("F:/xxx.jpg"));
}
@Test
public void fun2() throws FileNotFoundException, IOException {
VerifyCode vc = new VerifyCode();
BufferedImage bi = vc.getImage();
VerifyCode.output(bi, new FileOutputStream("F:/xxx.jpg"));
System.out.println(vc.getText());
}
}
package cn.itcast.image;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
public class VerifyCode {
private int w = 70;
private int h = 35;
private Random r = new Random();
// {"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_GB2312"}
private String[] fontNames = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};
// 可选字符
private String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
// 背景色
private Color bgColor = new Color(255, 255, 255);
// 验证码上的文本
private String text ;
// 生成随机的颜色
private Color randomColor () {
int red = r.nextInt(150);
int green = r.nextInt(150);
int blue = r.nextInt(150);
return new Color(red, green, blue);
}
// 生成随机的字体
private Font randomFont () {
int index = r.nextInt(fontNames.length);
String fontName = fontNames[index];//生成随机的字体名称
int style = r.nextInt(4);//生成随机的样式, 0(无样式), 1(粗体), 2(斜体), 3(粗体+斜体)
int size = r.nextInt(5) + 24; //生成随机字号, 24 ~ 28
return new Font(fontName, style, size);
}
// 画干扰线
private void drawLine (BufferedImage image) {
int num = 3;//一共画3条
Graphics2D g2 = (Graphics2D)image.getGraphics();
for(int i = 0; i < num; i++) {//生成两个点的坐标，即4个值
int x1 = r.nextInt(w);
int y1 = r.nextInt(h);
int x2 = r.nextInt(w);
int y2 = r.nextInt(h);
g2.setStroke(new BasicStroke(1.5F));
g2.setColor(Color.BLUE); //干扰线是蓝色
g2.drawLine(x1, y1, x2, y2);//画线
}
}
// 随机生成一个字符
private char randomChar () {
int index = r.nextInt(codes.length());
return codes.charAt(index);
}
// 创建BufferedImage
private BufferedImage createImage () {
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = (Graphics2D)image.getGraphics();
g2.setColor(this.bgColor);
g2.fillRect(0, 0, w, h);
return image;
}
// 调用这个方法得到验证码
public BufferedImage getImage () {
BufferedImage image = createImage();//创建图片缓冲区
Graphics2D g2 = (Graphics2D)image.getGraphics();//得到绘制环境
StringBuilder sb = new StringBuilder();//用来装载生成的验证码文本
// 向图片中画4个字符
for(int i = 0; i < 4; i++) {//循环四次，每次生成一个字符
String s = randomChar() + "";//随机生成一个字母
sb.append(s); //把字母添加到sb中
float x = i * 1.0F * w / 4; //设置当前字符的x轴坐标
g2.setFont(randomFont()); //设置随机字体
g2.setColor(randomColor()); //设置随机颜色
g2.drawString(s, x, h-5); //画图
}
this.text = sb.toString(); //把生成的字符串赋给了this.text
drawLine(image); //添加干扰线
return image;
}
// 返回验证码图片上的文本
public String getText () {
return text;
}
// 保存图片到指定的输出流
public static void output (BufferedImage image, OutputStream out)
throws IOException {
ImageIO.write(image, "JPEG", out);
}
}
login.jsp ：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'login.jsp' starting page
<%-- 本页面提供登录表单，还要显示错误信息 --%>
登录
<%
/*
读取名为uname的Cookie!
如果为空显示：""
如果不为空显示：Cookie的值
*/
String uname = "";
Cookie[] cs = request.getCookies();//获取请求中所有的cookie
if(cs != null) {// 如果存在cookie
for(Cookie c : cs) {//循环遍历所有的cookie
if("uname".equals(c.getName())) {//查找名为uname的cookie
uname = c.getValue();//获取这个cookie的值，给uname这个变量
}
}
}
%>
<%
String message = "";
String msg = (String)request.getAttribute("msg");//获取request域中的名为msg的属性
if(msg != null) {
message = msg;
}
%>
<%=message %>
succ1.jsp ：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'succ1.jsp' starting page
succ1
<%
String username = (String)session.getAttribute("username");
if(username == null) {
/*
1. 向request域中保存错误信息，转发到login.jsp
*/
request.setAttribute("msg", "您还没有登录，不要冒充领导！");
request.getRequestDispatcher("/session2/login.jsp").forward(request, response);
return;
}
%>
欢迎欢迎，热烈欢迎，欢迎<%=username %>领导指导工作！
succ2.jsp ：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'succ2.jsp' starting page
succ2
<%
String username = (String)session.getAttribute("username");
if(username == null) {
/*
1. 向request域中保存错误信息，转发到login.jsp
*/
request.setAttribute("msg", "您还没有登录，不要冒充领导！");
request.getRequestDispatcher("/session2/login.jsp").forward(request, response);
return;
}
%>
欢迎欢迎，热烈欢迎，欢迎<%=username %>领导指导工作！
VerifyCodeServlet.java
package cn.itcast.servlet;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import cn.itcast.image.VerifyCode;
public class VerifyCodeServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* 1. 生成图片
* 2. 保存图片上的文本到session域中
* 3. 把图片响应给客户端
*/
VerifyCode vc = new VerifyCode();
BufferedImage image = vc.getImage();
request.getSession().setAttribute("session_vcode", vc.getText());//保存图片上的文本到session域
VerifyCode.output(image, response.getOutputStream());
}
}
LoginServlet.java
package cn.itcast.servlet;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LoginServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/*
* 校验验证码
* 1. 从session中获取正确的验证码
* 2. 从表单中获取用户填写的验证码
* 3. 进行比较！
* 4. 如果相同，向下运行，否则保存错误信息到request域，转发到login.jsp
*/
String sessionCode = (String) request.getSession().getAttribute("session_vcode");
String paramCode = request.getParameter("verifyCode");
if(!paramCode.equalsIgnoreCase(sessionCode)) {
request.setAttribute("msg", "验证码错误！");
request.getRequestDispatcher("/session2/login.jsp").forward(request, response);
return;
}
/*
* 1. 获取表单数据
*/
// 处理中文问题
request.setCharacterEncoding("utf-8");
// 获取
String username = request.getParameter("username");
String password = request.getParameter("password");
/*
* 2. 校验用户名和密码是否正确
*/
if(!"itcast".equalsIgnoreCase(username)) {//登录成功
/*
* 附加项：把用户名保存到cookie中，发送给客户端浏览器
* 当再次打开login.jsp时，login.jsp中会读取request中的cookie，把它显示到用户名文本框中
*/
Cookie cookie = new Cookie("uname", username);//创建Cookie
cookie.setMaxAge(60*60*24);//设置cookie命长为1天
response.addCookie(cookie);//保存cookie
/*
* 3. 如果成功
* > 保存用户信息到session中
* > 重定向到succ1.jsp
*/
HttpSession session = request.getSession();//获取session
session.setAttribute("username", username);//向session域中保存用户名
response.sendRedirect("/day11_3/session2/succ1.jsp");
} else {//登录失败
/*
* 4. 如果失败
* > 保存错误信息到request域中
* > 转发到login.jsp
*/
request.setAttribute("msg", "用户名或密码错误!");
RequestDispatcher qr = request.getRequestDispatcher("/session2/login.jsp");//得到转发器
qr.forward(request, response);//转发
}
}
}
详解版：day11.doc