SpringMVC归纳-2(Session会话、拦截器)
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2023-10-17 09:01:48
要点： 1.HttpSession：一个session的建立是从一个用户向服务器发第一个请求开始，而以用户显式结束或session超时为结束，借助session能在一定时间内记录用户状态。 2.ModelAndView：既可以设置URL地址，又可以渲染视图。 3.HandlerInterceptor ......
要点：
1.httpsession：一个session的建立是从一个用户向服务器发第一个请求开始，而以用户显式结束或session超时为结束，借助session能在一定时间内记录用户状态。
2.modelandview：既可以设置url地址，又可以渲染视图。
3.handlerinterceptor：拦截器接口，通过实现改接口的三个方法（prehandle、posthandle、aftercompletion）可以自定义一个拦截器。
实例：
实现登录、购物车功能。
login.html
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>乐淘登录</title>
</head>
<body>
<form action="http://localhost:8888/login-commit" method="post">
<input type="submit" value="login">
</form>
</body>
</html>
mall.html
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>乐淘商场</title>
</head>
<body>
<form action="http://localhost:8888/shopcar" method="post">
<label>请选择要购买的书籍：<br>
<input type="checkbox" name="bookname" value="c prime plus">c prime plus<br>
<input type="checkbox" name="bookname" value="c prime plus2">c prime plus2<br>
<input type="checkbox" name="bookname" value="c prime plus3">c prime plus3<br>
<input type="checkbox" name="bookname" value="c prime plus4">c prime plus4<br>
</label>
<input type="submit" value="加入购物车">
</form>
<form action="http://localhost:8888/quit" method="post">
<input value="log out" type="submit">
</form>
</body>
</html>
myshoppingcar.html
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>乐淘购物车</title>
</head>
<body>
<h2>我的购物车：</h2>
<!--存在购买时显示已购书籍-->
<ul th:if="${books.size()} != 0">
<li th:each="bookcount:${books}" th:text="${bookcount}"></li>
</ul>
<!--无购买-->
<div th:if="${books.size()} == 0">
您未购买任何书籍！
</div>
<form action="http://localhost:8888/mall" method="get">
<input type="submit" value="继续购买">
</form>
</body>
</html>
books.java
package com.example.demo.controller.login;
import java.util.hashmap;
import java.util.map.entry;
import java.util.set;
public class books {
private hashmap<string,integer> books = new hashmap<string,integer>();
//根据请求url中获得的表单数组，更新已有书本
public void refreshbooks(string[] newbooks) {
for (string book:newbooks) {
if (books.containskey(book)) {
books.put(book, books.get(book)+1);
}else {
books.put(book, 1);
}
}
}
//获取books集合，送往页面
public set<entry<string, integer>> getbooks(){
return books.entryset();
}
}
logincontroller.java
package com.example.demo.controller.login;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpsession;
import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.postmapping;
@controller
public class logincontroller {
//登录界面
@getmapping("login")
public string getlogin(httpservletrequest req) {
httpsession session = req.getsession();
//已登录直接进入到商场
if (session.getattribute("login")!=null) {
return "redirect:mall";
}
return "login";
}
//登录请求处理
@postmapping("login-commit")
public string postlogin(httpservletrequest req) {
httpsession session = req.getsession();
//session标记登录状态
session.setattribute("login",true);
return "redirect:mall";
}
//退出登录，保留购物记录
@postmapping("quit")
public string quit(httpservletrequest req) {
httpsession session = req.getsession();
session.removeattribute("login");
return "redirect:login";
}
}
shoppingcontroller.java
package com.example.demo.controller.login;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpsession;
import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.postmapping;
import org.springframework.web.servlet.modelandview;
@controller
public class shoppingcontroller {
//商场
@getmapping("mall")
public string getmall() {
return "mall";
}
//我的购物车
@postmapping("shopcar")
public modelandview getshopcar(modelandview view,httpservletrequest req) {
httpsession session = req.getsession();
books books = (books) session.getattribute("shopcar");//session会话获取已购书籍
string[] newbooks = req.getparametervalues("bookname");//新的购物请求
//从未购买
if (books==null){
books = new books();
}
//刷新session会话
if (newbooks!=null) {
books.refreshbooks(newbooks);
session.setattribute("shopcar", books);
}
//刷新model，渲染视图
view.addobject("books",books.getbooks());
view.setviewname("myshoppingcar");
return view;
}
}
logininterceptor.java
package com.example.demo.controller.login;
import java.io.ioexception;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
import javax.servlet.http.httpsession;
import org.springframework.web.servlet.handlerinterceptor;
import org.springframework.web.servlet.modelandview;
//登录拦截器
public class logininterceptor implements handlerinterceptor {
@override
//在controller方法之前调用
public boolean prehandle(httpservletrequest req,httpservletresponse res,object handler) throws ioexception {
httpsession session = req.getsession();
if (session.getattribute("login") != null) {
system.out.println("login!");
return true;
}
res.sendredirect("login");
return false;
}
@override
public void posthandle(httpservletrequest req,httpservletresponse res,object handler,modelandview modelandview) throws exception {
//controller方法处理完，但html页面并未送出显示时调用
}
@override
public void aftercompletion(httpservletrequest req,httpservletresponse res,object handler,exception ex) {
//页面渲染完毕后调用，通常用来回收资源，类似于finally
}
}
springwebconfig.java
package com.example.demo.controller.login;
import org.springframework.boot.springbootconfiguration;
import org.springframework.web.servlet.config.annotation.interceptorregistry;
import org.springframework.web.servlet.config.annotation.webmvcconfigurer;
@springbootconfiguration
public class springwebconfig implements webmvcconfigurer{
//增加拦截器，可以对特定url设定拦截以检查是否登录
public void addinterceptors(interceptorregistry registry) {
//装载一个拦截器,可以使用通配符，或字符串数组
registry.addinterceptor(new logininterceptor()).addpathpatterns("/mall","/quit");
}
}
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