okhttp 客戶端什么時候緩存服務器響應？

Question

我在 java 中使用 okhttp 客戶端 3.5.0 來緩存響應，服務器響應具有以下緩存控制標頭：

緩存控制：私有，最大年齡=0，必須重新驗證

首先，我嘗試進行實際網絡調用以獲取服務器響應，然后在第二個請求中我想獲取緩存響應。

這是我的Java代碼：

HttpUrl.Builder httpUrlBuilder = HttpUrl.parse(serverUrl).newBuilder();

HttpUrl httpUrl = httpUrlBuilder.build();

Request request = new Request.Builder()
    .url(httpUrl)
    .cacheControl(new CacheControl.Builder().maxAge(1, TimeUnit.DAYS).build())
    .build();

Call call = okHttpClient.newCall(request);
call.enqueue(new Callback() {
    @Override
    public void onFailure(Call call, IOException e) {

    }

    @Override
    public void onResponse(Call call, final Response response) throws IOException {

        System.out.println("***************Response 1**************");

        System.out.println("isSucess:"+response.isSuccessful());

        Response text = response.cacheResponse();

        System.out.println("Cached Response:" + text);

        Response networkResponse = response.networkResponse();

        System.out.println("Network Response ::" +networkResponse);

    }
});

Thread.sleep(5000);


Request request2 = new Request.Builder()
    .cacheControl(new CacheControl.Builder().onlyIfCached().build())
    .url(httpUrlBuilder.build())
    .build();


call = okHttpClient.newCall(request2);
call.enqueue(new Callback() {
    @Override
    public void onFailure(Call call, IOException e) {

    }

    @Override
    public void onResponse(Call call, final Response response) throws IOException {
        System.out.println("***********Response 2************");

        System.out.println("isSucess:" +response.isSuccessful());

        final Response text = response.cacheResponse();

        System.out.println("Cached Response:" + text);

        Response networkResponse = response.networkResponse();

        System.out.println("Network Response:" +networkResponse);

    }
});

下面是第二個請求輸出：（部分輸出）

***********響應 2************

是成功：假

緩存響應：空

網絡響應：空

我是否遺漏了什么？

Answer 1

除非您閱讀並關閉響應正文，否則 OkHttp 不會緩存響應。 這就是觸發這些字節被下載和保存的原因。

try {
  if (response.cacheResponse() == null) {
    body.source().skip(Long.MAX_VALUE); // Exhaust response body.
  }
} finally {
  body.close();
}