OkHttp不缓存请求

Question

For some reason OkHttp response.cacheResponse() always returns null, even if request should be cached. In following code I'm making two requests to http://httpbin.org/cache/60 and I would expect, that second request would be fetched from cache. But it is not, as can be seen from output.

What am I missing?

Code:

@Test
public void test2_okhttp() throws IOException {
    int cacheSize = 100 * 1024 * 1024; // 100 MiB
    File cacheDir = new File("/tmp/ok_cache");
    cacheDir.mkdirs();

    Cache cache = new Cache(cacheDir, cacheSize);

    OkHttpClient client = new OkHttpClient.Builder()
            .cache(cache)
            .build();

    String url = "http://httpbin.org/cache/60";

    for(int i = 0; i < 2; i++) {
        Request request = new Request.Builder()
                .url(url)
                .build();

        Response response = client.newCall(request).execute();

        System.out.println("response1.cacheResponse() = " + response.cacheResponse());
        System.out.println("response1.networkResponse() = " + response.networkResponse());
    }
}

Output:

response1.cacheResponse() = null
response1.networkResponse() = Response{protocol=http/1.1, code=200, message=OK, url=http://httpbin.org/cache/60}
response1.cacheResponse() = null
response1.networkResponse() = Response{protocol=http/1.1, code=200, message=OK, url=http://httpbin.org/cache/60}

Answer 1

OkHttp writes the response body to the cache as a side-effect of you reading the body. Calling response.body().string() will do it, or you can read the body in another way.