okhttp3 url轮询负载均衡拦截器

new OkHttpClient.Builder().addInterceptor(new PollInterceptor(urls)).build()

添加日志拦截器：

HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
            httpLoggingInterceptor.setLevel(Level.BODY);
new OkHttpClient.Builder().addInterceptor(httpLoggingInterceptor).build()

话不多说直接上代码：

public class PollInterceptor implements Interceptor {
    // url
    private final String[] urls;
    // url size
    private final int size;
    // 计数：下次轮询服务下标
    private final AtomicInteger nextUrlCyclicCounter;

    
    public PollInterceptor(String[] urls) {
        this.urls = urls;
        this.size = urls.length;
        this.nextUrlCyclicCounter = new AtomicInteger(0);
    }

    
    @Override
    public Response intercept(Chain chain) throws IOException {
        // 获取原始的originalRequest
        Request originalRequest = chain.request();
        // 不需要负载均衡
        if (size < 2) {
            return chain.proceed(originalRequest);
        }
        // 获取老的url
        HttpUrl oldUrl = originalRequest.url();
        // 获取originalRequest的创建者builder
        Request.Builder builder = originalRequest.newBuilder();
        // 重建新的HttpUrl，需要重新设置的url部分
        HttpUrl newHttpUrl = getHttpUrl(oldUrl);
        // 获取新newRequest
        Request newRequest = builder.url(newHttpUrl).build();
        // 请求
        return chain.proceed(newRequest );
    }

    
    public HttpUrl getHttpUrl(HttpUrl oldUrl) {
        // 获取url下标
        int index  = incrementAndGetModulo();
        // 获取新的url
        HttpUrl baseURL = HttpUrl.parse(urls[index]);
        // 重建新的HttpUrl，需要重新设置的url部分
        assert baseURL != null;
        return oldUrl.newBuilder()
                .scheme(baseURL.scheme())// http协议如：http或者https
                .host(baseURL.host())// 主机地址
                .port(baseURL.port())// 端口
                .build();
    }

    
    public int incrementAndGetModulo() {
        for (; ; ) {
            int current = nextUrlCyclicCounter.get();
            int next = (current + 1) % size;
            if (nextUrlCyclicCounter.compareAndSet(current, next)) {
                return next;
            }
        }
    }
}

public int incrementAndGetModulo() {
        for (; ; ) {
            int current = nextUrlCyclicCounter.get();
            int next = (current + 1) % size;
            if (nextUrlCyclicCounter.compareAndSet(current, next)) {
                return next;
            }
        }
    }