项目启动时找不到`org.springframework.security.authentication.AuthenticationManager`

前言

项目启动报错，required a bean of type 'org.springframework.security.authentication.AuthenticationManager' that could not be found.

1 具体问题

项目启动报错，具体报错信息如下

2024-10-21 10:30:54.538 ERROR 17676 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Field loginService in com.haixin.initadmin.controller.system.SysLoginController required a bean of type 'org.springframework.security.authentication.AuthenticationManager' that could not be found.

The injection point has the following annotations:
	- @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'org.springframework.security.authentication.AuthenticationManager' in your configuration.

2 问题原因

项目启动创建SysLoginController时找不到org.springframework.security.authentication.AuthenticationManager

3 解决方案

1. 没有引入spring-boot-starter-securitypom依赖，如果是这个问题，一般在开发阶段就可以发现爆红出差。只需引入以下依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

2. 自定义配置类中定义AuthenticationManager Bean

在spring boot 2.0X的默认配置中，不再自动注册AuthenticationManager ，如果使用自定义的安全配置类，需要手动暴露AuthenticationManager Bean
如下：

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.config.annotation.authentication.configuration.AuthenticationConfiguration;

@Configuration
public class SecurityConfig {

    @Bean
    public AuthenticationManager authenticationManager(AuthenticationConfiguration authenticationConfiguration) throws Exception {
        return authenticationConfiguration.getAuthenticationManager();
    }
}

4 原理分析

AuthenticationManager是 Spring Security 框架中的一个核心接口，用于处理用户的认证逻辑。在应用程序中，当用户登录时，AuthenticationManager负责验证用户的凭据，并决定是否允许用户访问系统。