我们可以使用Springboot的登录拦截器进行登录验证，并完成登录跳转，错误的账户不进行跳转，正确的账户则跳转至success页面中。
同时添加登录拦截器，对于错误的账户不允许直接访问main.html页面。
实现步骤：
一.配置登录页面以及登录业务逻辑处理
1.首先建立一个springboot的项目，项目目录结构如下：
首先，我们需要导入Springboot相应的jar包，在pom.xml文件中进行添加：
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.zk.myspringboot_014</groupId> <artifactId>myspringboot_014</artifactId> <packaging>jar</packaging> <version>0.0.1-SNAPSHOT</version> <name>myspringboot_014 Maven Webapp</name> <url>http://maven.apache.org</url> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </dependency> <!-- 继承父包 --> <dependency> <groupId>org.webjars</groupId> <artifactId>jquery</artifactId> <version>3.3.1-1</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <dependency> <groupId>net.sourceforge.nekohtml</groupId> <artifactId>nekohtml</artifactId> </dependency> </dependencies> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.4.3.RELEASE</version> </parent> <build> <finalName>myspringboot_014</finalName> </build> </project>
接下来，建立我们的登录页面以及登录跳转页面login.html和main.html
login.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>用户登录</title>
</head>
<body>
<form action="/user/login" method="post">
用户名:<input name="username" type="text"/><br>
密码:<input name="password" type="password"> <br>
<input type="submit" value="登录">
</form>
</body>
</html>
main.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<meta name="description" content="">
<meta name="author" content="">
</head>
<body class="text-center">
success
</body>
</html>
可以看到，登录login.html页面中表单返回的action为/user/login，所以需要构建一个返回的LoginController.java
LoginController.java
package com.zk.myspringboot;
import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.*;
import javax.servlet.http.HttpSession;
import java.util.Map;
@Controller
public class LoginController {
// @DeleteMapping
// @PutMapping
// @GetMapping
//@RequestMapping(value = "/user/login",method = RequestMethod.POST)
@PostMapping(value = "/user/login")
public String login(@RequestParam("username") String username,
@RequestParam("password") String password,
Map<String,Object> map, HttpSession session){
if(!StringUtils.isEmpty(username) && "123456".equals(password)){
//登陆成功，防止表单重复提交，可以重定向到主页
session.setAttribute("loginUser",username);
return "redirect:/main.html";
}else{
//登陆失败
map.put("msg","用户名密码错误");
return "login";
}
}
}
(1)这里使用发送post请求，使用@PostMapping代替了RequestMapping（value="/login", method="post"）
(2)跳转页面时使用 return ”redirect:/ main.html“，而不是 return ”main“ 。这里会直接调用controller
最后加上启动项DemoApplication.java
DemoApplication.java
package com.zk.myspringboot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
二. 配置拦截器
当我们未在login.html页面输入用户名和密码时，直接访问main.html，此时也是可以访问到main.html文件的。这种操作不应当被允许，所以需要配置拦截器，当用户名与密码不正确时，页面无权跳转main.html，而直接跳转login.html
1.添加HandlerInterceptor拦截器
LoginHandlerInterceptor.java
package com.zk.myspringboot;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 登陆检查，
*/
public class LoginHandlerInterceptor implements HandlerInterceptor {
//目标方法执行之前
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
Object user = request.getSession().getAttribute("loginUser");
if(user == null){
//未登陆，返回登陆页面
request.setAttribute("msg","没有权限请先登陆");
request.getRequestDispatcher("/index.html").forward(request,response);
return false;
}else{
//已登陆，放行请求
return true;
}
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
}
}
在此拦截器中，需要取出LoginController.java中放在loginUser属性中的值进行判断，如果这个值为null，则未登录，返回原始登陆页面，否则放行请求。
2.配置WebMvcConfigurer 拦截器
需要让登录有个拦截器的功能，意思是除了访问首页我们可以，其他未登录的全部拦截下来，所以需要配置一个WebMvcConfigurer 拦截器：
MyMvcConfig.java
package com.zk.myspringboot;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
//@EnableWebMvc //不要接管SpringMVC
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//浏览器发送 /index 请求来到 login
registry.addViewController("/index").setViewName("login");
}
//所有的WebMvcConfigurerAdapter组件都会一起起作用
@Bean //将组件注册在容器
public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){
WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("login");
registry.addViewController("/index.html").setViewName("login");
registry.addViewController("/main.html").setViewName("main");
}
//注册拦截器
@Override
public void addInterceptors(InterceptorRegistry registry) {
//super.addInterceptors(registry);
//静态资源； *.css , *.js
//SpringBoot已经做好了静态资源映射
registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
.excludePathPatterns("/index.html","/","/user/login");
}
};
return adapter;
}
}
最后，application.properties配置如下：
spring.thymeleaf.cache=false spring.thymeleaf.mode=LEGACYHTML5
运行此程序，运行结果图如下：
