Android中CookieManager的底层实现

前几天，项目组有个技术问题，想用本地加载html， js写cookie的方法，绕过去。

想法是没有问题的，但是测试的时候发现，每次重新打开App，都取不到以前Cookie里面设的值。

后来去App/data下面找WebView.db，打开来一看，cookie情报根本没有存。

原因是js写cookie的时候，没有指明expire, WebKit默认把它当成临时cookie， webview终了之后就丢失了。

这个问题本身不复杂，不过趁机我看了一把Andorid底层读取Cookie的source root:

以下source root，转载请注明出自《南湖边上的小木屋》

1. 取Cookie的API

[java]
CookieManager.getInstance().getCookie(url);

2.CookieManager的getInstance()

[java]
/**
    * Gets the singleton CookieManager instance. If this method is used
    * before the application instantiates a {@link WebView} instance,
    * {@link CookieSyncManager#createInstance(Context)} must be called
    * first.
    *
    * @return the singleton CookieManager instance
    */
   public static synchronized CookieManager getInstance() {
       return WebViewFactory.getProvider().getCookieManager();
   }

3.WebViewFactory是个工厂模式，额
[java]
static synchronized WebViewFactoryProvider getProvider() {
    // For now the main purpose of this function (and the factory abstraction) is to keep
    // us honest and minimize usage of WebViewClassic internals when binding the proxy.
    if (sProviderInstance != null) return sProviderInstance;

    sProviderInstance = getFactoryByName(DEFAULT_WEB_VIEW_FACTORY);
    if (sProviderInstance == null) {
        if (DEBUG) Log.v(LOGTAG, "Falling back to explicit linkage");
        sProviderInstance = new WebViewClassic.Factory();
    }
    return sProviderInstance;
}

4.层层嵌套，最后生成的instance是CookieManagerClassic
[java]
@Override
       public CookieManager getCookieManager() {
           return CookieManagerClassic.getInstance();
       }

5. getCookie方法实现在CookieManagerClassic上
[java]
@Override
public String getCookie(String url) {
      return getCookie(url, false);
}

@Override
public String getCookie(String url, boolean privateBrowsing) {
      WebAddress uri;
      try {
          uri = new WebAddress(url);
      } catch (ParseException ex) {
          Log.e(LOGTAG, "Bad address: " + url);
          return null;
      }

      return nativeGetCookie(uri.toString(), privateBrowsing);
}

6. nativeGetCookie定义在CookieManager.cpp里，恩。。。。JNI。。。
[java]
static jstring getCookie(JNIEnv* env, jobject, jstring url, jboolean privateBrowsing)
{
    GURL gurl(jstringToStdString(env, url));
    CookieOptions options;
    options.set_include_httponly();
    std::string cookies = WebCookieJar::get(privateBrowsing)->cookieStore()->GetCookieMonster()->GetCookiesWithOptions(gurl, options);
    return stdStringToJstring(env, cookies);
}

7. WebCookieJar.cpp中，定义了从哪里去取得Cookie情报
[java]
WebCookieJar* WebCookieJar::get(bool isPrivateBrowsing)
{
    MutexLocker lock(instanceMutex);
    if (!isFirstInstanceCreated && fileSchemeCookiesEnabled)
        net::CookieMonster::EnableFileScheme();
    isFirstInstanceCreated = true;
    scoped_refptr<WebCookieJar>* instancePtr = instance(isPrivateBrowsing);
    if (!instancePtr->get())
        *instancePtr = new WebCookieJar(databaseDirectory(isPrivateBrowsing));
    return instancePtr->get();
}

[java]
static std::string databaseDirectory(bool isPrivateBrowsing)
{
    static const char* const kDatabaseFilename = "/webviewCookiesChromium.db";
    static const char* const kDatabaseFilenamePrivateBrowsing = "/webviewCookiesChromiumPrivate.db";

    std::string databaseFilePath = databaseDirectory();
    databaseFilePath.append(isPrivateBrowsing ? kDatabaseFilenamePrivateBrowsing : kDatabaseFilename);
    return databaseFilePath;
}

※Android3.0以上是webviewCookiesChromium.db, 以下是WebView.db文件

8.最后读取Cookie情报发生在cookie_monster.cc。额，最后调到C++，去读.db文件，无敌了

[java]
std::string CookieMonster::GetCookiesWithOptions(const GURL& url,
                                                 const CookieOptions& options) {
base::AutoLock autolock(lock_);
InitIfNecessary();

if (!HasCookieableScheme(url)) {
    return std::string();
}

TimeTicks start_time(TimeTicks::Now());

// Get the cookies for this host and its domain(s).
std::vector<CanonicalCookie*> cookies;
FindCookiesForHostAndDomain(url, options, true, &cookies);
std::sort(cookies.begin(), cookies.end(), CookieSorter);

std::string cookie_line;
for (std::vector<CanonicalCookie*>::const_iterator it = cookies.begin();
       it != cookies.end(); ++it) {
    if (it != cookies.begin())
      cookie_line += "; ";

补充：移动开发 , Android ,