OkHttp3實現Cookies管理及持久化

Cookies管理

OkHttp的原始碼過於複雜，感興趣的同學可以自行閱讀，這裡只針對 HttpEngineer 類進行分析，從字面意思即可看出這個類負責http請求的request、response等等操作的處理，而cookies管理也是隨著http請求的request、response來處理。

3.0之前

先看networkRequest方法，在裡面通過client.getCookieHandler()函式獲得了CookieHandler物件，通過該物件拿到cookie並設定到請求頭裡，請求結束後取得響應後通過networkResponse.headers()函式將請求頭獲得傳入receiveHeaders函式，並將取得的cookie存入getCookieHandler得到的一個CookieHandler物件中去

private Request networkRequest(Request request) throws IOException {
  Request.Builder result = request.newBuilder();

  //例行省略....

  CookieHandler cookieHandler = client.getCookieHandler();
  if (cookieHandler != null) {
    // Capture the request headers added so far so that they can be offered to the CookieHandler.
    // This is mostly to stay close to the RI; it is unlikely any of the headers above would
    // affect cookie choice besides "Host".
    Map<String, List<String>> headers = OkHeaders.toMultimap(result.build().headers(), null);

    Map<String, List<String>> cookies = cookieHandler.get(request.uri(), headers);

    // Add any new cookies to the request.
    OkHeaders.addCookies(result, cookies);
  }

  //例行省略....

  return result.build();
}

public void readResponse() throws IOException {
  //例行省略....

  receiveHeaders(networkResponse.headers());

  //例行省略....
}

public void receiveHeaders(Headers headers) throws IOException {
  CookieHandler cookieHandler = client.getCookieHandler();
  if (cookieHandler != null) {
    cookieHandler.put(userRequest.uri(), OkHeaders.toMultimap(headers, null));
  }
}

CookieHandler物件是OkHttpClient類中的一個屬性，傳入了這個物件，那麼OkHttp就會對cookie進行自動管理

private CookieHandler cookieHandler;
public OkHttpClient setCookieHandler(CookieHandler cookieHandler) {
  this.cookieHandler = cookieHandler;
  return this;
}

public CookieHandler getCookieHandler() {
  return cookieHandler;
}

OkHttpClient client = new OkHttpClient();
client.setCookieHandler(CookieHandler cookieHanlder);

3.0之後

而在OkHttp3中，對cookie而言，新增了兩個類 Cookiejar 、 Cookie 兩個類，在瞭解這兩個類之前，先去看一下 HttpEngine 關於cookie管理的變化

private Request networkRequest(Request request) throws IOException {
    Request.Builder result = request.newBuilder();

    //例行省略....

    List<Cookie> cookies = client.cookieJar().loadForRequest(request.url());
    if (!cookies.isEmpty()) {
      result.header("Cookie", cookieHeader(cookies));
    }

    //例行省略....

    return result.build();
  }

private String cookieHeader(List<Cookie> cookies) {
    StringBuilder cookieHeader = new StringBuilder();
    for (int i = 0, size = cookies.size(); i < size; i++) {
      if (i > 0) {
        cookieHeader.append("; ");
      }
      Cookie cookie = cookies.get(i);
      cookieHeader.append(cookie.name()).append('=').append(cookie.value());
    }
    return cookieHeader.toString();
  }

public void receiveHeaders(Headers headers) throws IOException {
    if (client.cookieJar() == CookieJar.NO_COOKIES) return;

    List<Cookie> cookies = Cookie.parseAll(userRequest.url(), headers);
    if (cookies.isEmpty()) return;

    client.cookieJar().saveFromResponse(userRequest.url(), cookies);
  }

通過以上幾個關鍵方法，可以很明顯的感覺到作者的意圖了，為了更加自由定製化的cookie管理。其中 loadForRequest() 、 saveFromResponse() 這兩個方法最為關鍵，分別是在傳送時向request header中加入cookie，在接收時，讀取response header中的cookie。現在再去看 Cookiejar 這個類，就很好理解了

public interface CookieJar {
  /** A cookie jar that never accepts any cookies. */
  CookieJar NO_COOKIES = new CookieJar() {
    @Override public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
    }

    @Override public List<Cookie> loadForRequest(HttpUrl url) {
      return Collections.emptyList();
    }
  };

  /**
   * Saves {@code cookies} from an HTTP response to this store according to this jar's policy.
   *
   * <p>Note that this method may be called a second time for a single HTTP response if the response
   * includes a trailer. For this obscure HTTP feature, {@code cookies} contains only the trailer's
   * cookies.
   */
  void saveFromResponse(HttpUrl url, List<Cookie> cookies);

  /**
   * Load cookies from the jar for an HTTP request to {@code url}. This method returns a possibly
   * empty list of cookies for the network request.
   *
   * <p>Simple implementations will return the accepted cookies that have not yet expired and that
   * {@linkplain Cookie#matches match} {@code url}.
   */
  List<Cookie> loadForRequest(HttpUrl url);
}

so!在OkHttpClient建立時，傳入這個CookieJar的實現，就能完成對Cookie的自動管理了

OkHttpClient client = new OkHttpClient.Builder()
    .cookieJar(new CookieJar() {
        private final HashMap<HttpUrl, List<Cookie>> cookieStore = new HashMap<>();

        @Override
        public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
            cookieStore.put(url, cookies);
        }

        @Override
        public List<Cookie> loadForRequest(HttpUrl url) {
            List<Cookie> cookies = cookieStore.get(url);
            return cookies != null ? cookies : new ArrayList<Cookie>();
        }
    })
    .build();

Cookies持久化

對Cookies持久化的方案，與之前版本並無很大區別，還是參考 android-async-http 這個庫，主要參考其中兩個類:

• PersistentCookieStore
• SerializableHttpCookie
  與之前版本的區別是要將對 java.net.HttpCookie 這個類的快取處理換成對 okhttp3.Cookie 的處理，其他方面幾乎一樣。

廢話不多說了，直接上程式碼

SerializableOkHttpCookies

主要做兩件事：

• 將Cookie物件輸出為ObjectStream
• 將ObjectStream序列化成Cookie物件

public class SerializableOkHttpCookies implements Serializable {

    private transient final Cookie cookies;
    private transient Cookie clientCookies;

    public SerializableOkHttpCookies(Cookie cookies) {
        this.cookies = cookies;
    }

    public Cookie getCookies() {
        Cookie bestCookies = cookies;
        if (clientCookies != null) {
            bestCookies = clientCookies;
        }
        return bestCookies;
    }

    private void writeObject(ObjectOutputStream out) throws IOException {
        out.writeObject(cookies.name());
        out.writeObject(cookies.value());
        out.writeLong(cookies.expiresAt());
        out.writeObject(cookies.domain());
        out.writeObject(cookies.path());
        out.writeBoolean(cookies.secure());
        out.writeBoolean(cookies.httpOnly());
        out.writeBoolean(cookies.hostOnly());
        out.writeBoolean(cookies.persistent());
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        String name = (String) in.readObject();
        String value = (String) in.readObject();
        long expiresAt = in.readLong();
        String domain = (String) in.readObject();
        String path = (String) in.readObject();
        boolean secure = in.readBoolean();
        boolean httpOnly = in.readBoolean();
        boolean hostOnly = in.readBoolean();
        boolean persistent = in.readBoolean();
        Cookie.Builder builder = new Cookie.Builder();
        builder = builder.name(name);
        builder = builder.value(value);
        builder = builder.expiresAt(expiresAt);
        builder = hostOnly ? builder.hostOnlyDomain(domain) : builder.domain(domain);
        builder = builder.path(path);
        builder = secure ? builder.secure() : builder;
        builder = httpOnly ? builder.httpOnly() : builder;
        clientCookies =builder.build();
    }
}

PersistentCookieStore

根據一定的規則去快取或者獲取Cookie:

public class PersistentCookieStore {
    private static final String LOG_TAG = "PersistentCookieStore";
    private static final String COOKIE_PREFS = "Cookies_Prefs";

    private final Map<String, ConcurrentHashMap<String, Cookie>> cookies;
    private final SharedPreferences cookiePrefs;

    public PersistentCookieStore(Context context) {
        cookiePrefs = context.getSharedPreferences(COOKIE_PREFS, 0);
        cookies = new HashMap<>();

        //將持久化的cookies快取到記憶體中 即map cookies
        Map<String, ?> prefsMap = cookiePrefs.getAll();
        for (Map.Entry<String, ?> entry : prefsMap.entrySet()) {
            String[] cookieNames = TextUtils.split((String) entry.getValue(), ",");
            for (String name : cookieNames) {
                String encodedCookie = cookiePrefs.getString(name, null);
                if (encodedCookie != null) {
                    Cookie decodedCookie = decodeCookie(encodedCookie);
                    if (decodedCookie != null) {
                        if (!cookies.containsKey(entry.getKey())) {
                            cookies.put(entry.getKey(), new ConcurrentHashMap<String, Cookie>());
                        }
                        cookies.get(entry.getKey()).put(name, decodedCookie);
                    }
                }
            }
        }
    }

    protected String getCookieToken(Cookie cookie) {
        return cookie.name() + "@" + cookie.domain();
    }

    public void add(HttpUrl url, Cookie cookie) {
        String name = getCookieToken(cookie);

        //將cookies快取到記憶體中 如果快取過期 就重置此cookie
        if (!cookie.persistent()) {
            if (!cookies.containsKey(url.host())) {
                cookies.put(url.host(), new ConcurrentHashMap<String, Cookie>());
            }
            cookies.get(url.host()).put(name, cookie);
        } else {
            if (cookies.containsKey(url.host())) {
                cookies.get(url.host()).remove(name);
            }
        }

        //講cookies持久化到本地
        SharedPreferences.Editor prefsWriter = cookiePrefs.edit();
        prefsWriter.putString(url.host(), TextUtils.join(",", cookies.get(url.host()).keySet()));
        prefsWriter.putString(name, encodeCookie(new SerializableOkHttpCookies(cookie)));
        prefsWriter.apply();
    }

    public List<Cookie> get(HttpUrl url) {
        ArrayList<Cookie> ret = new ArrayList<>();
        if (cookies.containsKey(url.host()))
            ret.addAll(cookies.get(url.host()).values());
        return ret;
    }

    public boolean removeAll() {
        SharedPreferences.Editor prefsWriter = cookiePrefs.edit();
        prefsWriter.clear();
        prefsWriter.apply();
        cookies.clear();
        return true;
    }

    public boolean remove(HttpUrl url, Cookie cookie) {
        String name = getCookieToken(cookie);

        if (cookies.containsKey(url.host()) && cookies.get(url.host()).containsKey(name)) {
            cookies.get(url.host()).remove(name);

            SharedPreferences.Editor prefsWriter = cookiePrefs.edit();
            if (cookiePrefs.contains(name)) {
                prefsWriter.remove(name);
            }
            prefsWriter.putString(url.host(), TextUtils.join(",", cookies.get(url.host()).keySet()));
            prefsWriter.apply();

            return true;
        } else {
            return false;
        }
    }

    public List<Cookie> getCookies() {
        ArrayList<Cookie> ret = new ArrayList<>();
        for (String key : cookies.keySet())
            ret.addAll(cookies.get(key).values());

        return ret;
    }

    /**
     * cookies 序列化成 string
     *
     * @param cookie 要序列化的cookie
     * @return 序列化之後的string
     */
    protected String encodeCookie(SerializableOkHttpCookies cookie) {
        if (cookie == null)
            return null;
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        try {
            ObjectOutputStream outputStream = new ObjectOutputStream(os);
            outputStream.writeObject(cookie);
        } catch (IOException e) {
            Log.d(LOG_TAG, "IOException in encodeCookie", e);
            return null;
        }

        return byteArrayToHexString(os.toByteArray());
    }

    /**
     * 將字串反序列化成cookies
     *
     * @param cookieString cookies string
     * @return cookie object
     */
    protected Cookie decodeCookie(String cookieString) {
        byte[] bytes = hexStringToByteArray(cookieString);
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes);
        Cookie cookie = null;
        try {
            ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
            cookie = ((SerializableOkHttpCookies) objectInputStream.readObject()).getCookies();
        } catch (IOException e) {
            Log.d(LOG_TAG, "IOException in decodeCookie", e);
        } catch (ClassNotFoundException e) {
            Log.d(LOG_TAG, "ClassNotFoundException in decodeCookie", e);
        }

        return cookie;
    }

    /**
     * 二進位制陣列轉十六進位制字串
     *
     * @param bytes byte array to be converted
     * @return string containing hex values
     */
    protected String byteArrayToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder(bytes.length * 2);
        for (byte element : bytes) {
            int v = element & 0xff;
            if (v < 16) {
                sb.append('0');
            }
            sb.append(Integer.toHexString(v));
        }
        return sb.toString().toUpperCase(Locale.US);
    }

    /**
     * 十六進位制字串轉二進位制陣列
     *
     * @param hexString string of hex-encoded values
     * @return decoded byte array
     */
    protected byte[] hexStringToByteArray(String hexString) {
        int len = hexString.length();
        byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4) + Character.digit(hexString.charAt(i + 1), 16));
        }
        return data;
    }
}

最終效果

完成對Cookie持久化之後，就可以對Cookiejar進行進一步修改了，最終效果：

/**
     * 自動管理Cookies
     */
    private class CookiesManager implements CookieJar {
        private final PersistentCookieStore cookieStore = new PersistentCookieStore(getApplicationContext());

        @Override
        public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
            if (cookies != null && cookies.size() > 0) {
                for (Cookie item : cookies) {
                    cookieStore.add(url, item);
                }
            }
        }

        @Override
        public List<Cookie> loadForRequest(HttpUrl url) {
            List<Cookie> cookies = cookieStore.get(url);
            return cookies;
        }
    }

Tips

在這樣做之前，嘗試了使用 Interceptor 和 NetWorkInterceptor 在Http請求request和response時，攔截響應鏈，加入對Cookie的管理。so！接下來可能會詳細介紹下 Interceptor 這個非常酷的實現。