接着上节的讲，在添加了@EnableWebSecurity注解后，如果需要自定义一些配置，则需要和继承WebSecurityConfigurerAdapter后，覆盖某些方法。
我们来看一下WebSecurityConfigurerAdapter中哪些方法可以重写，需要重写。
（1）WebSecurity
默认是一个空方法，一般也不会再重写。
public void configure(WebSecurity web) throws Exception { }
（2）HttpSecurity
默认的父类代码默认任何request都需要认证，使用默认的login page基于表单认证，使用HTTP基本认证。
protected void configure(HttpSecurity http) throws Exception { http .authorizeRequests() .anyRequest().authenticated() .and() .formLogin().and() .httpBasic(); }
下面是一些自定义写法。
@Override protected void configure(HttpSecurity http) throws Exception { //@formatter:off http.authorizeRequests() // all users have access to these urls .antMatchers("/resources/**", "/signup", "/about").permitAll() // Any URL that starts with "/admin/" will be restricted to users who have the role "ROLE_ADMIN" .antMatchers("/admin/**").hasRole("ADMIN") // Any URL that starts with "/db/" requires the user to have both "ROLE_ADMIN" and "ROLE_DBA" .antMatchers("/db/**").access("hasRole('ADMIN') and hasRole('DBA')") // Any URL that starts with "/group_a/" requires the user to have both "ROLE_ADMIN" or "ROLE_GROUP_A" .antMatchers("/admin/**").hasAnyRole("ADMIN", "GROUP_A") // Any URL that has not already been matched on only requires that the user be authenticated .anyRequest().authenticated() .and().formLogin() // all users have access to custom login page .loginPage("/login").permitAll() .and().logout() // customize logout url .logoutUrl("/my/logout") // customize logout success url .logoutSuccessUrl("/my/index") // specify a custom LogoutSuccessHandler. If this is specified, logoutSuccessUrl() is ignored .logoutSuccessHandler(logoutSuccessHandler) // invalidate the HttpSession at the time of logout. This is true by default .invalidateHttpSession(true) // Adds a LogoutHandler. SecurityContextLogoutHandler is added as the last LogoutHandler by default .addLogoutHandler(logoutHandler) // Allows specifying the names of cookies to be removed on logout success .deleteCookies() .and().rememberMe() // Add remember me function and valid date. .key("uniqueAndSecret") .tokenValiditySeconds(60 * 60 * 24 * 7); //@formatter:on }
（3）AuthenticationManagerBuilder
默认是这样写的：
protected void configure(AuthenticationManagerBuilder auth) throws Exception { this.disableLocalConfigureAuthenticationBldr = true; }
由上一节分析可知，它其实默认使用DefaultPasswordEncoderAuthenticationManagerBuilder这个Builder及自动配置的UserDetails和UserDetailsService。
protected AuthenticationManager authenticationManager() throws Exception { if (!authenticationManagerInitialized) {
// [1]如果覆盖configure()方法，则disableLocalConfigureAuthenticationBldr为false
// [2]如果是默认的configure()方法，disableLocalConfigureAuthenticationBldr还是true configure(localConfigureAuthenticationBldr); if (disableLocalConfigureAuthenticationBldr) { authenticationManager = authenticationConfiguration .getAuthenticationManager(); // [2] } else { authenticationManager = localConfigureAuthenticationBldr.build(); // [1] } authenticationManagerInitialized = true; } return authenticationManager; }
如果被覆盖，虽然还是使用的DefaultPasswordEncoderAuthenticationManagerBuilder，但是我们可以使用UserDetailsManagerConfigurer（的两个子类InMemoryUserDetailsManagerConfigurer，JdbcUserDetailsManagerConfigurer）来构建UserDetailsService及UserDetails。以InMemoryUserDetailsManagerConfigurer为例，下面是自定义的写法。
@Bean PasswordEncoder passwordEncoder() { return PasswordEncoderFactories.createDelegatingPasswordEncoder(); } @Override protected void configure(AuthenticationManagerBuilder auth) throws Exception { //@formatter:off // returns InMemoryUserDetailsManagerConfigurer PasswordEncoder encoder = new BCryptPasswordEncoder(); auth.inMemoryAuthentication() // create a UserDetailsBuilder and add to userBuilders .withUser("user").password("{bcrypt}" + encoder.encode("pass")).roles("USER") // returns InMemoryUserDetailsManagerConfigurer .and() // create a UserDetailsBuilder again and add to userBuilders
.withUser("admin").password("{bcrypt}" + encoder.encode("pass")).roles("USER", "ADMIN"); //@formatter:on }[注] 框架要求密码必须加密，所以这里加了有关password encode的支持。
那么这段代码如何生成UserDetailsService及UserDetails的呢？流程如下：
[1] 调用AuthenticationManagerBuilder的inMemoryAuthentication()方法创建InMemoryUserDetailsManagerConfigurer，调用InMemoryUserDetailsManagerConfigurer的构造器时则会创建InMemoryUserDetailsManager（即UserDetailsService的实现类），最终经过层层父类（InMemoryUserDetailsManagerConfigurer -> UserDetailsManagerConfigurer -> UserDetailsServiceConfigurer -> AbstractDaoAuthenticationConfigurer）设定到AbstractDaoAuthenticationConfigurer中。
public InMemoryUserDetailsManagerConfigurer<AuthenticationManagerBuilder> inMemoryAuthentication() throws Exception { return apply(new InMemoryUserDetailsManagerConfigurer<>()); }
public InMemoryUserDetailsManagerConfigurer() { super(new InMemoryUserDetailsManager(new ArrayList<>())); }
protected AbstractDaoAuthenticationConfigurer(U userDetailsService) { this.userDetailsService = userDetailsService; provider.setUserDetailsService(userDetailsService); if (userDetailsService instanceof UserDetailsPasswordService) { this.provider.setUserDetailsPasswordService((UserDetailsPasswordService) userDetailsService); } }
[2] 调用AuthenticationManagerBuilder的apply()方法设定defaultUserDetailsService为[1]的InMemoryUserDetailsManager并且把[1]的InMemoryUserDetailsManagerConfigurer加到父类AbstractConfiguredSecurityBuilder的configurers list中
private <C extends UserDetailsAwareConfigurer<AuthenticationManagerBuilder, ? extends UserDetailsService>> C apply( C configurer) throws Exception { this.defaultUserDetailsService = configurer.getUserDetailsService(); return (C) super.apply(configurer); }
[3] 调用InMemoryUserDetailsManagerConfigurer的父类UserDetailsManagerConfigurer的withUser()方法生成多个UserDetailsBuilder放在userBuilders list中
public final UserDetailsBuilder withUser(String username) { UserDetailsBuilder userBuilder = new UserDetailsBuilder((C) this); userBuilder.username(username); this.userBuilders.add(userBuilder); return userBuilder; }
[4] 当调用DefaultPasswordEncoderAuthenticationManagerBuilder的build()方法时，则会调用
[4.1] 调用UserDetailsServiceConfigurer的configure()方法
@Override public void configure(B builder) throws Exception { initUserDetailsService(); super.configure(builder); }
[4.2] 调用UserDetailsManagerConfigurer的initUserDetailsService()方法通过[3]的userBuilders创建User对象（UserDetails的实现类），并且从[1]中的AbstractDaoAuthenticationConfigurer获取UserDetailsService，并把UserDetails放到UserDetailsService中。
@Override protected void initUserDetailsService() throws Exception { for (UserDetailsBuilder userBuilder : userBuilders) { getUserDetailsService().createUser(userBuilder.build()); } for (UserDetails userDetails : this.users) { getUserDetailsService().createUser(userDetails); } }
下面是一些自定义写法：
@Override protected void configure(AuthenticationManagerBuilder auth) throws Exception { //@formatter:off // returns InMemoryUserDetailsManagerConfigurer auth.inMemoryAuthentication() // create a UserBuilder and add to userBuilders .withUser("user").password("password").roles("USER") // returns InMemoryUserDetailsManagerConfigurer .and() // create a UserBuilder again and add to userBuilders .withUser("admin").password("password").roles("USER", "ADMIN"); //@formatter:on }
（4）authenticationManagerBean()
我们覆盖了configure(AuthenticationManagerBuilder auth)后，我们使用了AuthenticationManagerBuilder 的实现类DefaultPasswordEncoderAuthenticationManagerBuilder，通过InMemoryUserDetailsManagerConfigurer创建自己的UserDetailsService的实现类InMemoryUserDetailsManager及User，系统还会默认给我们创建AuthenticationProvider的实现类DaoAuthenticationProvider。但是我们发现，这些对象并不是Spring Bean。所以我们可以通过覆盖该方法并且声明为一个Bean，这样就可以在项目中注入并使用这个Bean了。
@Bean(name = "myAuthenticationManager") @Override public AuthenticationManager authenticationManagerBean() throws Exception { return super.authenticationManagerBean(); }
通过父类的源码可以看到，实际上在调用时，创建了一个AuthenticationManager代理。
public AuthenticationManager authenticationManagerBean() throws Exception { return new AuthenticationManagerDelegator(authenticationBuilder, context); }
（5）userDetailsServiceBean()
和（4）类似，Override this method to expose a UserDetailsService created from configure(AuthenticationManagerBuilder) as a bean. In general only thefollowing override should be done of this method：
@Bean(name = "myUserDetailsService") @Override public UserDetailsService userDetailsServiceBean() throws Exception { return super.userDetailsServiceBean(); }
（6） UserDetailsService
还记得第三章的UserDetailsService实现类是如何生成的吗？这里做一个简述：
[1] AuthenticationConfiguration中创建InitializeUserDetailsBeanManagerConfigurer Bean。
[2] build时调用InitializeUserDetailsBeanManagerConfigurer的内部类InitializeUserDetailsManagerConfigurer的configure()方法。
[3] 在ApplicationContext中获取UserDetailsService（by type），如果没有找到自定义的UserDetailsService Bean，则UserDetailsServiceAutoConfiguration生效，会lazy load一个InMemoryUserDetailsManager；反之，则使用我们自定义的UserDetailsService Bean。
在WebSecurityConfigurerAdapter中，userDetailsServiceBean()和userDetailsService()两个方法内容实际上都是一样的。都是获取当前环境中（自定义的或系统生成的InMemoryUserDetailsManager）的UserDetailsService的代理类。所以，该类一般不需要重写，如果想自定义自己的UserDetailsService，可以直接实现UserDetailsService接口，并且把该类声明为一个Spring Bean：
@Servicepublic class MyUserDetailsService implements UserDetailsService { @Override public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException { // TODO Auto-generated method stub return null; }}
当然你也可以直接覆盖该方法并声明为一个Bean：
@Bean @Override public UserDetailsService userDetailsService() { return (username) -> { AppUser user = appUserRepository.findOneByUsername(username); if (user == null) { throw new UsernameNotFoundException("Incorrect username or password."); } return user; }; }
需要注意的是，我们也要有UserDetails的实现类供UserDetailsService处理。
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