Spring Security身份认证和权限控制代码

Spring Security身份认证和权限控制代码可以通过配置文件或者Java代码实现。其中，配置文件方式需要在Spring配置文件中添加如下代码：

<security:http auto-config="true" use-expressions="true">
    <security:intercept-url pattern="/admin/**" access="hasRole('ROLE_ADMIN')" />
    <security:intercept-url pattern="/user/**" access="hasRole('ROLE_USER')" />
    <security:form-login login-page="/login" default-target-url="/home" authentication-failure-url="/login?error" />
    <security:logout logout-success-url="/login?logout" />
</security:http>

<security:authentication-manager>
    <security:authentication-provider>
        <security:user-service>
            <security:user name="admin" password="admin" authorities="ROLE_ADMIN" />
            <security:user name="user" password="user" authorities="ROLE_USER" />
        </security:user-service>
    </security:authentication-provider>
</security:authentication-manager>

在Java代码中，可以通过继承WebSecurityConfigurerAdapter类来实现身份认证和权限控制，示例代码如下：

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
        auth.inMemoryAuthentication()
            .withUser("admin").password("admin").roles("ADMIN")
            .and()
            .withUser("user").password("user").roles("USER");
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
            .antMatchers("/admin/**").hasRole("ADMIN")
            .antMatchers("/user/**").hasRole("USER")
            .and()
            .formLogin()
            .loginPage("/login")
            .defaultSuccessUrl("/home")
            .failureUrl("/login?error")
            .and()
            .logout()
            .logoutSuccessUrl("/login?logout");
    }
}

以上是Spring Security身份认证和权限控制的代码示例。