Spring Security(4)：自定义配置

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：

@Service
public 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。