Spring-Security-入门（一）：登录与退出
前言
Spring Security 比较复杂，愿与各位一起研究使用，有歧义的地方，欢迎指出，谢谢！
Github 地址
https://github.com/ChinaSilence/any-spring-security.git 本文示例地址：https://github.com/ChinaSilence/any-spring-security/tree/master/security-login-no-db
启动应用
1、clone 代码之后，进入 目录，启动应用
mvn spring-boot:run2、demo 演示，地址：http://localhost:8080 账号 anoy 密码 pwd
相关解释说明
注解 @EnableWebSecurity
在 Spring boot 应用中使用 Spring Security，用到了 @EnableWebSecurity注解，官方说明如下：
/**
* Add this annotation to an {@code @Configuration} class to have the Spring Security
* configuration defined in any {@link WebSecurityConfigurer} or more likely by extending
* the {@link WebSecurityConfigurerAdapter} base class and overriding individual methods:
*/意思是说， 该注解和 @Configuration 注解一起使用, 注解 WebSecurityConfigurer 类型的类，或者利用 @EnableWebSecurity 注解继承 WebSecurityConfigurerAdapter的类，这样就构成了 Spring Security 的配置。
抽象类 WebSecurityConfigurerAdapter
一般情况，会选择继承 WebSecurityConfigurerAdapter 类，其官方说明如下：
/**
* Provides a convenient base class for creating a {@link WebSecurityConfigurer}
* instance. The implementation allows customization by overriding methods.
*
* <p>
* Will automatically apply the result of looking up
* {@link AbstractHttpConfigurer} from {@link SpringFactoriesLoader} to allow
* developers to extend the defaults.
* To do this, you must create a class that extends AbstractHttpConfigurer and then create a file in the classpath at "META-INF/spring.factories" that looks something like:
* </p>
* <pre>
* org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer = sample.MyClassThatExtendsAbstractHttpConfigurer
* </pre>
* If you have multiple classes that should be added you can use "," to separate the values. For example:
*
* <pre>
* org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer = sample.MyClassThatExtendsAbstractHttpConfigurer, sample.OtherThatExtendsAbstractHttpConfigurer
* </pre>
*
*/意思是说 WebSecurityConfigurerAdapter 提供了一种便利的方式去创建 WebSecurityConfigurer的实例，只需要重写 WebSecurityConfigurerAdapter 的方法，即可配置拦截什么URL、设置什么权限等安全控制。
方法 configure(AuthenticationManagerBuilder auth) 和 configure(HttpSecurity http)
Demo 中重写了 WebSecurityConfigurerAdapter 的两个方法：
/**
* 通过 {@link #authenticationManager()} 方法的默认实现尝试获取一个 {@link AuthenticationManager}.
* 如果被复写, 应该使用{@link AuthenticationManagerBuilder} 来指定 {@link AuthenticationManager}.
*
* 例如, 可以使用以下配置在内存中进行注册公开内存的身份验证{@link UserDetailsService}:
*
* // 在内存中添加 user 和 admin 用户
* @Override
* protected void configure(AuthenticationManagerBuilder auth) {
* auth
* .inMemoryAuthentication().withUser("user").password("password").roles("USER").and()
* .withUser("admin").password("password").roles("USER", "ADMIN");
* }
*
* // 将 UserDetailsService 显示为 Bean
* @Bean
* @Override
* public UserDetailsService userDetailsServiceBean() throws Exception {
* return super.userDetailsServiceBean();
* }
*
*/
protected void configure(AuthenticationManagerBuilder auth) throws Exception {
this.disableLocalConfigureAuthenticationBldr = true;
}/**
* 复写这个方法来配置 {@link HttpSecurity}.
* 通常，子类不能通过调用 super 来调用此方法，因为它可能会覆盖其配置。 默认配置为：
*
* http.authorizeRequests().anyRequest().authenticated().and().formLogin().and().httpBasic();
*
*/
protected void configure(HttpSecurity http) throws Exception {
logger.debug("Using default configure(HttpSecurity). If subclassed this will potentially override subclass configure(HttpSecurity).");
http
.authorizeRequests()
.anyRequest().authenticated()
.and()
.formLogin().and()
.httpBasic();
}final 类 HttpSecurity
表1 HttpSecurity 常用方法及说明
用于基于 OpenId 的验证类 AuthenticationManagerBuilder
/**
* {@link SecurityBuilder} used to create an {@link AuthenticationManager}. Allows for
* easily building in memory authentication, LDAP authentication, JDBC based
* authentication, adding {@link UserDetailsService}, and adding
* {@link AuthenticationProvider}'s.
*/意思是， AuthenticationManagerBuilder 用于创建一个 AuthenticationManager，让我能够轻松的实现内存验证、LADP验证、基于JDBC的验证、添加 UserDetailsService、添加 AuthenticationProvider。
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