目录
IDEA配置
然后可以看到默认给你一个Hello World
然后注意端口占用的问题
JSP基本语法
page指令
Language:定义要使用的脚本语言,默认为java
contentType:定义jsp字符的编码和页面相应的MIME类型
pageEncodeing:定义jsp页面的字符集编码
ScriptLet标签
作用:在jsp中嵌入java代码
<%! %> 定义全局变量,方法,类
<% %>定义局部变量,方法,类
<%= %>输出一个变量或者具体内容
注释
html可见<%-- --%> html不可见
包含
静态包含: <%@include file="文件地址" %> 先包含,再编译处理
动态包含: <jsp:include page="文件地址" > 先编译处理,再包含
跳转
forward1.jsp
<jsp:forward page="forward2.jsp">
<jsp:param name="username" value="java"/>
<jsp:param name="password" value="123456"/>
</jsp:forward>
forward2.jsp
username:<%=request.getParameter("username")%>
password:<%=request.getParameter("password")%>
JSP四大作用域
application
有效范围是整个应用,从应用启动到应用结束
<%
application.setAttribute("application","applicationValue");
%>
<%
String applicationValue=(String) application.getAttribute("application");
%>
<%=applicationValue%>
<%
String applicationValue=(String) application.getAttribute("application");
%>
<%=applicationValue%>
session
有效范围是当前会话,从用户打开浏览器开始到用户关闭浏览器这段时间
代码中application换成session
换一个浏览器就会变成null
request
有效范围是一次请求
<%
request.setAttribute("request","requestValue");
%>
<%
String requestValue=(String) request.getAttribute("request");
%>
<%=requestValue%>
<jsp:forward page="requestScope2.jsp"></jsp:forward>
<%
String requestValue=(String) request.getAttribute("request");
%>
<%=requestValue%>
page
有效范围仅限于用户请求的当前页面
JSP九大内置对象
response
response代表的是对客户端的响应,主要是将JSP容器处理过的对象传回到客户端。response对象也具有作用域,它只在JSP页面内有效
自动刷新应用,页面重定向,操作cookie
自动刷新应用(没隔一秒)
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="java.util.*"%>
<html>
<head>
<title>Title</title>
<%
response.setHeader("refresh","1");
Date now=new Date();
%>
</head>
<body>
当前时间:<%=now.toLocaleString()%>
</body>
</html>
页面重定向(无法传参)
<%
response.sendRedirect("index.jsp");
%>
简单登录
responseLogin.jsp
<%--
Created by IntelliJ IDEA.
User: Initial
Date: 2024-01-05
Time: 13:16
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
<%
String username=null;
String password=null;
Cookie[] cookies=request.getCookies();
for(int i=0;cookies!=null && i<cookies.length;i++){
if(cookies[i].getName().equals("userNameAndPassword")){
username=cookies[i].getValue().split("xxx")[0];
password=cookies[i].getValue().split("xxx")[1];
}
}
if(username==null){
username="";
}
if(password==null){
password="";
}
%>
</head>
<body>
<form action="responseMain.jsp" method="get">
<table>
<tr>
<td>用户名</td>
<td><input type="text" name="username" id="username" value="<%=username%>" placeholder="请输入用户名"/> </td>
</tr>
<tr>
<td>密码</td>
<td><input type="password" name="password" id="password" value="<%=password%>" placeholder="请输入密码"/> </td>
</tr>
<tr>
<td><input type="checkbox" name="remember" id="remember" value="rememberMe"/></td>
<td>记住密码</td>
</tr>
<tr>
<td><input type="submit" value="登录"/> </td>
<td><input type="reset" value="重置"/></td>
</tr>
</table>
</form>
</body>
</html>
responseMain.jsp
<%--
Created by IntelliJ IDEA.
User: Initial
Date: 2024-01-05
Time: 13:22
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
<%
String username=(String) request.getParameter("username");
String password=(String) request.getParameter("password");
String remember=(String) request.getParameter("remember");
if(remember.equals("rememberMe")){
Cookie userNameAndPassword=new Cookie("userNameAndPassword",username+"xxx"+password);
userNameAndPassword.setMaxAge(1*24*60*60);
response.addCookie(userNameAndPassword);
}
System.out.println("到此一游");
response.sendRedirect("responseLogin.jsp");
%>
</head>
<body>
username:<%=username%><br>
password:<%=password%><br>
remember:<%=remember%><br>
</body>
</html>
out
out对象用于在web浏览器内输出信息,并且管理应用服务器上的输出缓冲区。在使用out对象输出数据时,可以对数据缓冲区进行操作,及时
清除缓冲区中的残余数据,为其他的输出让出缓冲空间。待数据输出完毕后,要及时关闭输出流。
导入tomcat中的jsp-api和servlet-api包
pageContext
pageContext对象的作用是取得任何范围的参数,通过它可以获取JSP页面的out,request,reponse,session,application等对象
pageContext对象的创建和初始化都是由容器来完成的,在jsp页面可以直接使用pageContext对象
<%
pageContext.setAttribute("pageContext","pageContext");
request.setAttribute("request","request");
session.setAttribute("session","session");
application.setAttribute("application","application");
String pageContextValue=(String) pageContext.getAttribute("pageContext");
String requestValue=(String) pageContext.getRequest().getAttribute("request");
String sessionValue=(String) pageContext.getSession().getAttribute("session");
String applicationValue=(String) pageContext.getServletContext().getAttribute("application");
%>
<%=pageContextValue%>
<%=requestValue%>
<%=sessionValue%>
<%=applicationValue%>
config
config对象的主要作用是取得服务器的配置信息。通过pageContext对象的getServletConfig()方法可以获取一个config对象
当一个Servlet初始化时,容器把某些信息通过config对象传递给这个Servlet.开发者可以在web.xml文件中为应用程序环境中的Servlet
程序和JSP页面提供初始化参数
config1.jsp
<%response.sendRedirect("config2");%>
config2.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
<%
String a=config.getInitParameter("key");
%>
</head>
<body>
<%=a%>
</body>
</html>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>config2</servlet-name>
<jsp-file>/config2.jsp</jsp-file>
<init-param>
<param-name>key</param-name>
<param-value>123456</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>config2</servlet-name>
<url-pattern>/config2</url-pattern>
</servlet-mapping>
</web-app>
exception
exception.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page errorPage="error.jsp"%>
<html>
<head>
<title>Title</title>
</head>
<body>
<%
int a=1;
int b=0;
int c=a/b;
%>
</body>
</html>
error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isErrorPage="true"%>
<html>
<head>
<title>Title</title>
</head>
<body>
您的程序出错了
<%
if(exception!=null){
out.println("错误信息:");
out.println(exception.getMessage());
}
%>
</body>
</html>
JavaBean组件
JavaBean组件引入
JavaBean是使用Java语言开发的一个可重用的组件,在JSP开发中可以使用JavaBean减少重复代码,使得整个JSP代码的开发更加灵活简洁
创建JavaBean
<jsp:userBean id="实例化对象的名称" scope="保存范围(默认page)" class="类完整名称"/>
设置属性值
<jsp:setProperty property="属性名称" name="实例化对象的名称" value="属性的值" param="参数名称"/>
Property="*" 匹配所以的属性
或者
获取属性值
<jsp:getProperty property="属性名称" name="实例化对象的名称"/>
JavaBean的保存范围
page,request,session,application
JavaBean的删除
作用域对象,removeAttribute("javabean的名称");
<%
pageContext.removeAttribute("teacher");
%>
Servlet
HelloWorld
ctrl+o快速调出重写方法
注意编码问题
配置映射
生命周期
Servlet类加载->实例化->服务->销毁
两种页面跳转方式
客户端跳转:不能获取request中的参数,能获取session,application中的参数
response.sendRedirect("目标地址")
服务端跳转:能获取request中的参数,也能获取session,application中的参数
RequestDispatcher rd=request.getRequestDispatcher("main.jsp");
rd.forward(request,response);
demo代码
package com.example.servlet;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class ServerSkipServlet extends HttpServlet {
private static final long serialVersionUID = 6436509275737527901L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setAttribute("request","requestValue");
HttpSession session= request.getSession();
session.setAttribute("session","sessionValue");
ServletContext application= request.getServletContext();
application.setAttribute("application","applicationValue");
//客户端跳转 response.sendRedirect("main.jsp");
//服务端跳转
RequestDispatcher rd=request.getRequestDispatcher("main.jsp");
rd.forward(request,response);
}
}
main.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%
String requestValue=(String) request.getAttribute("request");
String sessionValue=(String) session.getAttribute("session");
String applicationValue=(String) application.getAttribute("application");
%>
<%=requestValue%>
<%=sessionValue%>
<%=applicationValue%>
</body>
</html>
JSP&Servlet实现用户登录
index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>用户登录</title>
</head>
<body>
<form action="login" method="post">
<table>
<tr>
<td>用户名:</td>
<td><input type="text" name="username"/></td>
</tr>
<tr>
<td>密码:</td>
<td><input type="password" name="password"/></td>
</tr>
<tr>
<td><input type="submit" value="提交"/></td>
<td><input type="reset" value="重置"/></td>
</tr>
<tr>
<td></td>
<td>
<%
String msg=(String) request.getAttribute("msg");
if(msg==null){
msg="";
}
%>
<%=msg%>
</td>
</tr>
</table>
</form>
</body>
</html>
java
package com.example.servlet;
import com.example.entity.User;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class LoginServlet extends HttpServlet{
/**
*
*/
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username=request.getParameter("username");
String password=request.getParameter("password");
HttpSession session=request.getSession();
if(username.equals("admin") && password.equals("123456")){
User currentUser=new User();
currentUser.setUsername(username);
currentUser.setPassword(password);
session.setAttribute("currentUser", currentUser);
response.sendRedirect("login.jsp");
}else{
request.setAttribute("msg", "用户名或密码错误!");
RequestDispatcher rd=request.getRequestDispatcher("index.jsp");
rd.forward(request, response);
}
}
}
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="com.example.entity.User" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>主页</title>
</head>
<body>
欢迎您！！！<%User currentUser=(User)session.getAttribute("currentUser"); %><%=currentUser.getUsername() %>
</body>
</html>
User.java
package com.example.entity;
public class User {
private Integer id;
private String username;
private String password;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
web.xml
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.example.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
Servlet过滤器
web.xml添加过滤器
<filter>
<filter-name>LoginFilter</filter-name>
<filter-class>com.example.filter.LoginFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>LoginFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
过滤器demo代码
package com.example.filter;
import com.example.entity.User;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class LoginFilter implements Filter{
@Override
public void destroy() {
}
@Override
public void init(FilterConfig arg0) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest request=(HttpServletRequest)servletRequest;
HttpServletResponse response=(HttpServletResponse)servletResponse;
HttpSession session=request.getSession();
User currentUser=(User)session.getAttribute("currentUser");
String path=request.getServletPath();
if(currentUser==null&& !path.contains("login")){
RequestDispatcher rd=request.getRequestDispatcher("index.jsp");
rd.forward(request, response);
}else{
filterChain.doFilter(servletRequest, servletResponse);
}
}
}
Servlet监听器
web.xml中配置
<listener>
<listener-class>com.example.listener.SessionListener</listener-class>
</listener>
监听器demo代码
package com.example.listener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
public class SessionListener implements HttpSessionAttributeListener {
@Override
public void attributeAdded(HttpSessionBindingEvent event) {
System.out.println("在session里面添加了值,键为: "+event.getName()+" 值为: "+event.getValue());
}
@Override
public void attributeRemoved(HttpSessionBindingEvent event) {
}
@Override
public void attributeReplaced(HttpSessionBindingEvent event) {
}
}
EL表达式
内置对象
EL表达式访问范围属性
page->request->session->application
EL表达式接收请求参数
param:单个参数
paramValues:数组参数
EL表达式对象操作
EL表达式集合操作
