本文主要应用了OkHttp的Interceptor来实现自定义重试次数
虽然OkHttp自带retryOnConnectionFailure(true)方法可以实现重试，但是不支持自定义重试次数，所以有时并不能满足我们的需求。
#1.自定义重试拦截器：
/**
* 重试拦截器
*/
public class RetryIntercepter implements Interceptor { public int maxRetry;//最大重试次数
private int retryNum = ;//假如设置为3次重试的话，则最大可能请求4次（默认1次+3次重试） public RetryIntercepter(int maxRetry) {
this.maxRetry = maxRetry;
} @Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
System.out.println("retryNum=" + retryNum);
Response response = chain.proceed(request);
while (!response.isSuccessful() && retryNum < maxRetry) {
retryNum++;
System.out.println("retryNum=" + retryNum);
response = chain.proceed(request);
}
return response;
}
}
#2.测试场景类：
public class RetryTest {
String mUrl = "https://www.baidu.com/";
OkHttpClient mClient;
@Before
public void setUp() {
HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.setLevel(HttpLoggingInterceptor.Level.BODY);
mClient = new OkHttpClient.Builder()
.addInterceptor(new RetryIntercepter())//重试
.addInterceptor(logging)//网络日志
.addInterceptor(new TestInterceptor())//模拟网络请求
.build();
}
@Test
public void testRequest() throws IOException {
Request request = new Request.Builder()
.url(mUrl)
.build();
Response response = mClient.newCall(request).execute();
System.out.println("onResponse:" + response.body().string());
}
class TestInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
String url = request.url().toString();
System.out.println("url=" + url);
Response response = null;
if (url.equals(mUrl)) {
String responseString = "{\"message\":\"我是模拟的数据\"}";//模拟的错误的返回值
response = new Response.Builder()
.code()
.request(request)
.protocol(Protocol.HTTP_1_0)
.body(ResponseBody.create(MediaType.parse("application/json"), responseString.getBytes()))
.addHeader("content-type", "application/json")
.build();
} else {
response = chain.proceed(request);
}
return response;
}
}
}
#3.输出结果：
retryNum=
--> GET https://www.baidu.com/ HTTP/1.1
--> END GET
url=https://www.baidu.com/
<-- null https://www.baidu.com/ (13ms)
content-type: application/json {"message":"我是模拟的数据"}
<-- END HTTP (-byte body)
retryNum=
--> GET https://www.baidu.com/ HTTP/1.1
--> END GET
url=https://www.baidu.com/
<-- null https://www.baidu.com/ (0ms)
content-type: application/json {"message":"我是模拟的数据"}
<-- END HTTP (-byte body)
retryNum=
--> GET https://www.baidu.com/ HTTP/1.1
--> END GET
url=https://www.baidu.com/
<-- null https://www.baidu.com/ (0ms)
content-type: application/json {"message":"我是模拟的数据"}
<-- END HTTP (-byte body)
retryNum=
--> GET https://www.baidu.com/ HTTP/1.1
--> END GET
url=https://www.baidu.com/
<-- null https://www.baidu.com/ (0ms)
content-type: application/json {"message":"我是模拟的数据"}
<-- END HTTP (-byte body)
onResponse:{"message":"我是模拟的数据"}
#4.结果分析：
>1. 这里我用一个TestInterceptor拦截器拦截掉真实的网络请求，实现response.code的自定义
2. 在RetryIntercepter中，通过response.isSuccessful()来对响应码进行判断，循环调用了多次chain.proceed(request)来实现重试拦截
3. 从输出中可以看到，一共请求了4次（默认1次+重试3次）。
#5.其它实现方式
如果你是使用OkHttp+Retrofit+RxJava，你也可以使用retryWhen操作符：retryWhen(new RetryWithDelay())来实现重试机制
public class RetryWithDelay implements Func1<Observable<? extends Throwable>, Observable<?>> {
private final int maxRetries;
private final int retryDelayMillis;
private int retryCount;
public RetryWithDelay(int maxRetries, int retryDelayMillis) {
this.maxRetries = maxRetries;
this.retryDelayMillis = retryDelayMillis;
}
@Override
public Observable<?> call(Observable<? extends Throwable> attempts) {
return attempts
.flatMap(new Func1<Throwable, Observable<?>>() {
@Override
public Observable<?> call(Throwable throwable) {
if (++retryCount <= maxRetries) {
// When this Observable calls onNext, the original Observable will be retried (i.e. re-subscribed).
LogUtil.print("get error, it will try after " + retryDelayMillis + " millisecond, retry count " + retryCount);
return Observable.timer(retryDelayMillis,
TimeUnit.MILLISECONDS);
}
// Max retries hit. Just pass the error along.
return Observable.error(throwable);
}
});
}
}