okhttp 问题总结 response.body().contentLength() = -1

前言: 今日付出的汗水，只为明日不一样的自己。唯有坚持不懈的努力，才能过上自己想要的生活

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http://blog.csdn.net/w690333243/article/details/78609258
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一、如果想要打印okhttp的log

则logging-interceptor版本要和okhttp版本保持一致
如：

compile 'com.squareup.okhttp3:logging-interceptor:3.4.1'compile 'com.squareup.okhttp3:okhttp:3.4.1'

否则报错：

Process: com.demo.okhttp, PID: 25567java.lang.NoClassDefFoundError: Failed resolution of: Lokhttp3/internal/Platform;at okhttp3.logging.HttpLoggingInterceptor$Logger$1.log(HttpLoggingInterceptor.java:109)at okhttp3.logging.HttpLoggingInterceptor.intercept(HttpLoggingInterceptor.java:157)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:200)at okhttp3.RealCall$AsyncCall.execute(RealCall.java:147)at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)at java.lang.Thread.run(Thread.java:818)Caused by: java.lang.ClassNotFoundException: Didn't find class "okhttp3.internal.Platform" on path: DexPathList[[zip file "/data/app/com.demo.okhttp-2/base.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_dependencies_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_0_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_1_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_2_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_3_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_4_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_5_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_6_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_7_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_8_apk.apk", zip file "/data/app/com.demo.okhttp-2/split_lib_slice_9_apk.apk"],nativeLibraryDirectories=[/vendor/lib64, /system/lib64]]at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)at java.lang.ClassLoader.loadClass(ClassLoader.java:511)......at java.lang.Thread.run(Thread.java:818) Suppressed: java.lang.ClassNotFoundException: okhttp3.internal.Platformat java.lang.Class.classForName(Native Method)at java.lang.BootClassLoader.findClass(ClassLoader.java:781)

二、response.body().contentLength() = -1

遇到response.body().contentLength() = -1时，打印okhttp log会发现http响应中有Transfer-encoding
解决办法：服务端使用response.setContentLength()，传入文件大小参数，但是有个问题，setContentLength()中参数类型时int型的，故受int最大值的限制。
再次查阅资料：
参考：
http://www.mamicode.com/info-detail-1329765.html
https://zhidao.baidu.com/question/198114215.html

最终解决办法：
在服务端设置

response.setHeader("Content-Length",String.valueOf(file.length()));

请帮我回答stackoverflow中的这个问题，以帮助更多的人，我没有翻墙账号，谢谢
https://stackoverflow.com/questions/42199020/custom-retrofit-2-1-response-body-getting-contentlenth-as-1

因为okhttp中的response.body().contentLength()是读取响应头中的Content-Length字段来设置的，并不是阻塞加载整个文件后获取的文件大小
看okhttp源码

@Override public Response intercept(Chain chain) throws IOException {    Request userRequest = chain.request();    Request.Builder requestBuilder = userRequest.newBuilder();    RequestBody body = userRequest.body();    if (body != null) {      MediaType contentType = body.contentType();      if (contentType != null) {        requestBuilder.header("Content-Type", contentType.toString());      }      long contentLength = body.contentLength();      if (contentLength != -1) {        requestBuilder.header("Content-Length", Long.toString(contentLength));        requestBuilder.removeHeader("Transfer-Encoding");      } else {        requestBuilder.header("Transfer-Encoding", "chunked");        requestBuilder.removeHeader("Content-Length");      }    }    if (userRequest.header("Host") == null) {      requestBuilder.header("Host", hostHeader(userRequest.url(), false));    }    if (userRequest.header("Connection") == null) {      requestBuilder.header("Connection", "Keep-Alive");    }    // If we add an "Accept-Encoding: gzip" header field we're responsible for also decompressing    // the transfer stream.    boolean transparentGzip = false;    if (userRequest.header("Accept-Encoding") == null && userRequest.header("Range") == null) {      transparentGzip = true;      requestBuilder.header("Accept-Encoding", "gzip");    }    List<Cookie> cookies = cookieJar.loadForRequest(userRequest.url());    if (!cookies.isEmpty()) {      requestBuilder.header("Cookie", cookieHeader(cookies));    }    if (userRequest.header("User-Agent") == null) {      requestBuilder.header("User-Agent", Version.userAgent());    }    Response networkResponse = chain.proceed(requestBuilder.build());    HttpHeaders.receiveHeaders(cookieJar, userRequest.url(), networkResponse.headers());    Response.Builder responseBuilder = networkResponse.newBuilder()        .request(userRequest);    if (transparentGzip        && "gzip".equalsIgnoreCase(networkResponse.header("Content-Encoding"))        && HttpHeaders.hasBody(networkResponse)) {      GzipSource responseBody = new GzipSource(networkResponse.body().source());      Headers strippedHeaders = networkResponse.headers().newBuilder()          .removeAll("Content-Encoding")          .removeAll("Content-Length")          .build();      responseBuilder.headers(strippedHeaders);      String contentType = networkResponse.header("Content-Type");      responseBuilder.body(new RealResponseBody(contentType, -1L, Okio.buffer(responseBody)));    }    return responseBuilder.build();  }

三、打印okhttp log时，在下载文件过程中卡顿

在做下载文件功能时，加了拦截日志监听，会发现点击下载按钮后，过了一段时间(下载的文件比稍微大点<55MB>)进度条才开始执行，后来找打一篇文章，里面隐约看到和log有关，说是开启log监听的话，会把整个文件加入内存。去掉log监听后，点击下载，进度条立即就可以执行了。

https://stackoverflow.com/questions/39545629/noclassdeffounderror-failed-resolution-of-lokhttp3-internal-platform
http://blog.csdn.net/yankai0219/article/details/8269922
http://blog.csdn.net/liwujun11111/article/details/52170337
http://blog.csdn.net/huntcode/article/details/47016529
http://blog.csdn.net/kmyhy/article/details/6032237