HttpResponseCache 在 Android Lollipop 中不起作用 [英] HttpResponseCache not working in Android Lollipop

问题描述

我一直在我的应用程序中成功使用 HttpResponseCache，但是当我的手机更新到 Lollipop 时，我意识到 HttpResponseCache 现在永远不会命中"，总是执行网络请求.我已经确认在 Lollipop 之前的 Android 版本中仍然运行良好.也许是我做错了什么，随着新的 Android 变化出现了.

I've been using in my app HttpResponseCache successfully, but when my phone updated to Lollipop I realized that HttpResponseCache now never get "hit", always do the network request. I've confirmed that in Android versions pre Lollipop are still working well. Maybe it's something that I did wrong and with new Android changes it has been appeared.

有人知道吗?

我的代码:

应用程序类，onCreate...

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        try {
            File httpCacheDir = new File(getApplicationContext().getCacheDir()
                    , "http");
            long httpCacheSize = 10 * 1024 * 1024;
            HttpResponseCache.install(httpCacheDir, httpCacheSize);
        } catch (IOException e) {
            Log.i(TAG, "HTTP response cache installation failed:" + e);
        }
    } else {
        try {
            File httpCacheDir = new File(getCacheDir(), "http");
            long httpCacheSize = 10 * 1024 * 1024;
            Class.forName("android.net.http.HttpResponseCache")
                    .getMethod("install", File.class, long.class)
                    .invoke(null, httpCacheDir, httpCacheSize);
        } catch (Exception e) {
                Log.i(TAG, "HTTP response cache installation failed:" + 
        }
    }

管理请求的功能

public static InputStream fetchInputStream(String strURL, boolean forceRefresh)
        throws IOException {

    HttpURLConnection mHttpConn = null;
    InputStream inputStream = null;
    URL url = new URL(strURL);
    HttpResponseCache cache;

    try {
        mHttpConn = (HttpURLConnection) url.openConnection();

        if (forceRefresh) {
            mHttpConn.addRequestProperty("Cache-Control", "no-cache");
        }

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
            cache = HttpResponseCache.getInstalled();
            if (cache != null) {

                    Log.i("TEST CACHE", "TEST PETICION: Req count: "
                            + cache.getRequestCount() + ", hit count "
                            + cache.getHitCount() + ", netWork count "
                            + cache.getNetworkCount() + "   size = "
                            + cache.size() + " <-----------------");

            }
        }

        mHttpConn.setUseCaches(true);
        mHttpConn.setDefaultUseCaches(true);
        mHttpConn.setRequestMethod("GET");
        mHttpConn.setConnectTimeout(30000);
        mHttpConn.setReadTimeout(30000);
        mHttpConn.connect();

        if (mHttpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
            inputStream = mHttpConn.getInputStream();
        }


    } catch (IOException ex) {
        Log.e("NetworkConnectionManager InputStream", "Exception opening ["
                + strURL + "] ->", ex);
        mHttpConn.disconnect();

        throw ex;
    }

    return inputStream;
}

每次请求后

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        HttpResponseCache cache = HttpResponseCache.getInstalled();

        if (cache != null) {
            cache.flush();
        }
    }

示例请求标头:

• 缓存控制 → max-age=300
• 连接→保持活动
• 内容编码 → gzip
• 内容类型→应用程序/json；字符集=utf-8
• 日期 → 2015 年 4 月 8 日，星期三，格林威治标准时间 12:37:35
• 到期 → 格林威治标准时间 2015 年 4 月 8 日星期三 12:42:35
• 上次修改时间 → 2015 年 4 月 8 日，星期三 12:37:35 GMT
• 服务器 → nginx
• 传输编码 → 分块
• 变化 → 接受编码
• X 缓存 → 未命中

推荐答案

在遇到这个问题几天后，我遇到了这个问题.它在 Marshmallow 中再次修复.

After having this problem for days I ran into this issue. It is fixed again in Marshmallow.

这是棒棒糖中的一个错误，其中 Vary -> Accept-Encoding 标头破坏了缓存，因为 Accept-Encoding 在默认情况下被填充但没有被写入.

It is a bug in lollipop where the Vary - > Accept-Encoding header breaks the cache because Accept-Encoding gets filled in by default but not written away.

这是问题的链接:

https://code.google.com/p/android/问题/详细信息?id=162475

修复方法是显式设置接受编码:

The fix is to set the Accept-Encoding explicitly:

接受编码 -> gzip

Accept-Encoding -> gzip

或

接受编码 -> 身份

在阅读方面，您必须将其添加到输入流的阅读中:

On the reading side you have to add this to the reading of the input stream:

String encoding = urlConnection.getHeaderField("Content-Encoding");
boolean gzipped = encoding!=null && encoding.toLowerCase().contains("gzip");
Inputstream inputStream;
if(gzipped)
    inputStream = new GZIPInputStream(urlConnection.getInputStream());
else
    inputstream = urlConnection.getInputStream();

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