详解Java设计模式之外观模式

public interface GatewayFilter {
​
    void handle(HttpServletRequest request, HttpServletResponse response, GatewayFilterChain filterChain) throws ServletException, IOException;
​
}

@ConfigurationProperties("gateway")
public class GatewayProperties {
    // 配置白名单列表
    private List<String> allowList = new ArrayList<>();
​
    public List<String> getAllowList() {
        return allowList;
    }
​
    public void setAllowList(List<String> allowList) {
        this.allowList = allowList;
    }
}

public class GatewayFilterImpl implements GatewayFilter {
​
    public static final String X_REAL_IP = "X-Real-IP";
    private List<String> allowList;
​
    public GatewayFilterImpl(List<String> allowList) {
        this.allowList = allowList;
    }
​
    @Override
    public void handle(HttpServletRequest request, HttpServletResponse response, GatewayFilterChain filterChain) throws ServletException, IOException {
        String remoteAddr = request.getHeader(X_REAL_IP);
        if (validateIp(remoteAddr)) {
            filterChain.doFilter(request, response);
        } else {
            response.sendError(HttpStatus.UNAUTHORIZED.value(), "Your IP address is not allowed to access the API.");
        }
    }
​
    // 验证当前 IP 是否在白名单列表中
    private boolean validateIp(String remoteAddr) {
        if (allowList == null || allowList.isEmpty()) {
            return true;
        }
​
        return allowList.contains(remoteAddr);
    }
}

@Configuration
@ConditionalOnClass(GatewayFilter.class)
@ConditionalOnProperty(prefix = "gateway", name = "enabled", havingValue = "true", matchIfMissing = true)
@EnableConfigurationProperties(GatewayProperties.class)
public class GatewayAutoConfiguration {
​
    @Bean
    public GatewayFilter gatewayFilter(GatewayProperties gatewayProperties) {
        return new GatewayFilterImpl(gatewayProperties.getAllowList());
    }
​
    @Bean
    public FilterRegistrationBean registration(GatewayFilter gatewayFilter) {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(gatewayFilter);
        registration.addUrlPatterns("/*");
        registration.setName("gatewayFilter");
        registration.setOrder(Ordered.LOWEST_PRECEDENCE);
        return registration;
    }
​
}

# application.properties
​
gateway.enabled=true
gateway.allowList=127.0.0.1,192.168.1.2