BAEL-4018 Spring Security - Already logged in user redirect from the login page

spring-security-modules/spring-security-mvc-boot-2/src/main/java/com/baeldung/loginredirect/LoginPageFilter.java

@@ -0,0 +1,39 @@
+package com.baeldung.loginredirect;
+
+import org.apache.http.HttpStatus;
+import org.springframework.security.authentication.AnonymousAuthenticationToken;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.web.filter.GenericFilterBean;
+
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+class LoginPageFilter extends GenericFilterBean {
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
+        if (isAuthenticated() && ((HttpServletRequest) request).getRequestURI().equals("/loginUser")) {
+
+            String encodedRedirectURL = ((HttpServletResponse) response).encodeRedirectURL(
+              ((HttpServletRequest) request).getContextPath() + "/userMainPage");
+
+            ((HttpServletResponse) response).setStatus(HttpStatus.SC_TEMPORARY_REDIRECT);
+            ((HttpServletResponse) response).setHeader("Location", encodedRedirectURL);
+        }
+        chain.doFilter(request, response);
+    }
+
+    private boolean isAuthenticated() {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        if (authentication == null || authentication instanceof AnonymousAuthenticationToken) {
+            return false;
+        }
+        return authentication.isAuthenticated();
+    }
+}

spring-security-modules/spring-security-mvc-boot-2/src/main/java/com/baeldung/loginredirect/LoginPageInterceptor.java

@@ -0,0 +1,39 @@
+package com.baeldung.loginredirect;
+
+import org.apache.http.HttpStatus;
+import org.springframework.security.authentication.AnonymousAuthenticationToken;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
+import org.springframework.web.util.UrlPathHelper;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+class LoginPageInterceptor extends HandlerInterceptorAdapter {
+
+    @Override
+    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
+
+        UrlPathHelper urlPathHelper = new UrlPathHelper();
+        if (urlPathHelper.getLookupPathForRequest(request).equals("/loginUser") && isAuthenticated()) {
+
+            String encodedRedirectURL = response.encodeRedirectURL(
+              request.getContextPath() + "/userMainPage");
+            response.setStatus(HttpStatus.SC_TEMPORARY_REDIRECT);
+            response.setHeader("Location", encodedRedirectURL);
+
+            return false;
+        } else {
+            return true;
+        }
+    }
+
+    private boolean isAuthenticated() {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        if (authentication == null || authentication instanceof AnonymousAuthenticationToken) {
+            return false;
+        }
+        return authentication.isAuthenticated();
+    }
+}

spring-security-modules/spring-security-mvc-boot-2/src/main/java/com/baeldung/loginredirect/LoginRedirectApplication.java

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+package com.baeldung.loginredirect;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+//@ImportResource({"classpath*:spring-security-login-redirect.xml"})
+class LoginRedirectApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(LoginRedirectApplication.class, args);
+    }
+}

spring-security-modules/spring-security-mvc-boot-2/src/main/java/com/baeldung/loginredirect/LoginRedirectMvcConfig.java

@@ -0,0 +1,14 @@
+package com.baeldung.loginredirect;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+class LoginRedirectMvcConfig implements WebMvcConfigurer {
+
+    @Override
+    public void addInterceptors(InterceptorRegistry registry) {
+        registry.addInterceptor(new LoginPageInterceptor());
+    }
+}

spring-security-modules/spring-security-mvc-boot-2/src/main/java/com/baeldung/loginredirect/LoginRedirectSecurityConfig.java

@@ -0,0 +1,43 @@
+package com.baeldung.loginredirect;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
+import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;
+
+@Configuration
+@EnableWebSecurity
+class LoginRedirectSecurityConfig extends WebSecurityConfigurerAdapter {
+
+    @Override
+    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
+        auth.inMemoryAuthentication().withUser("user").password(encoder().encode("user")).roles("USER");
+    }
+
+    @Override
+    protected void configure(HttpSecurity http) throws Exception {
+
+        http
+          .addFilterAfter(new LoginPageFilter(), UsernamePasswordAuthenticationFilter.class)
+
+          .authorizeRequests()
+          .antMatchers("/loginUser").permitAll()
+          .antMatchers("/user*").hasRole("USER")
+
+          .and().formLogin().loginPage("/loginUser").loginProcessingUrl("/user_login")
+          .failureUrl("/loginUser?error=loginError").defaultSuccessUrl("/userMainPage").permitAll()
+
+          .and().logout().logoutUrl("/user_logout").logoutSuccessUrl("/loginUser").deleteCookies("JSESSIONID")
+          .and().csrf().disable();
+    }
+
+    @Bean
+    public static PasswordEncoder encoder() {
+        return new BCryptPasswordEncoder();
+    }
+}

spring-security-modules/spring-security-mvc-boot-2/src/main/java/com/baeldung/loginredirect/UsersController.java

@@ -0,0 +1,32 @@
+package com.baeldung.loginredirect;
+
+import org.springframework.security.authentication.AnonymousAuthenticationToken;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+
+@Controller
+class UsersController {
+
+    @GetMapping("/userMainPage")
+    public String getUserPage() {
+        return "userMainPage";
+    }
+
+    @GetMapping("/loginUser")
+    public String getUserLoginPage() {
+        if (isAuthenticated()) {
+            return "redirect:userMainPage";
+        }
+        return "loginUser";
+    }
+
+    private boolean isAuthenticated() {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        if (authentication == null || authentication instanceof AnonymousAuthenticationToken) {
+            return false;
+        }
+        return authentication.isAuthenticated();
+    }
+}

spring-security-modules/spring-security-mvc-boot-2/src/main/resources/spring-security-login-redirect.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns="http://www.springframework.org/schema/beans"
+       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns:mvc="http://www.springframework.org/schema/mvc"
+       xmlns:beans="http://www.springframework.org/schema/beans"
+       xmlns:security="http://www.springframework.org/schema/security"
+       xsi:schemaLocation="
+        http://www.springframework.org/schema/mvc
+        http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
+       http://www.springframework.org/schema/security
+        http://www.springframework.org/schema/security/spring-security-5.2.xsd
+		http://www.springframework.org/schema/beans
+		http://www.springframework.org/schema/beans/spring-beans.xsd">
+
+    <security:authentication-manager>
+        <security:authentication-provider>
+            <security:user-service>
+                <security:user name="user" password="{noop}user" authorities="ROLE_USER"/>
+            </security:user-service>
+        </security:authentication-provider>
+    </security:authentication-manager>
+
+    <security:http pattern="/**" use-expressions="true" auto-config="true">
+        <security:intercept-url pattern="/loginUser" access="permitAll"/>
+        <security:intercept-url pattern="/user*" access="hasRole('ROLE_USER')"/>
+
+        <security:form-login login-page="/loginUser"
+                             login-processing-url="/user_login"
+                             authentication-failure-url="/loginUser?error=loginError"
+                             default-target-url="/userMainPage"/>
+        <security:csrf disabled="true"/>
+        <security:logout logout-url="/user_logout" delete-cookies="JSESSIONID" logout-success-url="/loginUser"/>
+
+
+        <security:custom-filter after="BASIC_AUTH_FILTER" ref="loginPageFilter"/>
+    </security:http>
+
+    <beans:bean id="loginPageFilter" class="com.baeldung.loginredirect.LoginPageFilter"/>
+
+    <mvc:interceptors>
+        <mvc:interceptor>
+            <mvc:mapping path="/loginUser"/>
+            <bean class="com.baeldung.loginredirect.LoginPageInterceptor"/>
+        </mvc:interceptor>
+    </mvc:interceptors>
+</beans>

spring-security-modules/spring-security-mvc-boot-2/src/main/resources/templates/userMainPage.html

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+<!DOCTYPE html>
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
+<title>Baeldung Login Redirect</title>
+</head>
+<body>
+Welcome user! <a th:href="@{/user_logout}" >Logout</a>
+</body>
+</html>