OkHttp3實(shí)現(xiàn)Cookies持續(xù)化管理

參考：https://www.zhihu.com/question/19786827
http://www.open-open.com/lib/view/open1453422314105.html

COOKIE和SESSION 是什么？？？

  1. 由于HTTP協(xié)議是無狀態(tài)的協(xié)議，所以服務(wù)端需要記錄用戶的狀態(tài)時(shí)，就需要用某種機(jī)制來識具體的用戶，這個(gè)機(jī)制就是Session.典型的場景比如購物車，當(dāng)你點(diǎn)擊下單按鈕時(shí)，由于HTTP協(xié)議無狀態(tài)，所以并不知道是哪個(gè)用戶操作的，所以服務(wù)端要為特定的用戶創(chuàng)建了特定的Session，用于標(biāo)識這個(gè)用戶，并且跟蹤用戶，這樣才知道購物車?yán)锩嬗袔妆緯?。這個(gè)Session是保存在服務(wù)端的，有一個(gè)唯一標(biāo)識。在服務(wù)端保存Session的方法很多，內(nèi)存、數(shù)據(jù)庫、文件都有。集群的時(shí)候也要考慮Session的轉(zhuǎn)移，在大型的網(wǎng)站，一般會(huì)有專門的Session服務(wù)器集群，用來保存用戶會(huì)話，這個(gè)時(shí)候 Session 信息都是放在內(nèi)存的，使用一些緩存服務(wù)比如Memcached之類的來放 Session。
  2. 思考一下服務(wù)端如何識別特定的客戶？這個(gè)時(shí)候Cookie就登場了。每次HTTP請求的時(shí)候，客戶端都會(huì)發(fā)送相應(yīng)的Cookie信息到服務(wù)端。實(shí)際上大多數(shù)的應(yīng)用都是用 Cookie 來實(shí)現(xiàn)Session跟蹤的，第一次創(chuàng)建Session的時(shí)候，服務(wù)端會(huì)在HTTP協(xié)議中告訴客戶端，需要在 Cookie 里面記錄一個(gè)Session ID，以后每次請求把這個(gè)會(huì)話ID發(fā)送到服務(wù)器，我就知道你是誰了。有人問，如果客戶端的瀏覽器禁用了 Cookie 怎么辦？一般這種情況下，會(huì)使用一種叫做URL重寫的技術(shù)來進(jìn)行會(huì)話跟蹤，即每次HTTP交互，URL后面都會(huì)被附加上一個(gè)諸如 sid=xxxxx 這樣的參數(shù)，服務(wù)端據(jù)此來識別用戶。

在OkHttp3中，對cookie而言，新增了兩個(gè)類Cookiejar 、 Cookie 兩個(gè)類，在了解這兩個(gè)類之前，先去看一下 HttpEngine 關(guān)于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(gè)關(guān)鍵方法，可以很明顯的感覺到作者的意圖了，為了更加自由定制化的cookie管理。其中loadForRequest() 、 saveFromResponse() 這兩個(gè)方法最為關(guān)鍵，分別是在發(fā)送時(shí)向request header中加入cookie，在接收時(shí)，讀取response header中的

Cookies持久化
對Cookies持久化的方案，與之前版本并無很大區(qū)別，還是參考 android-async-http 這個(gè)庫，主要參考其中兩個(gè)類:
-PersistentCookieStore

  • SerializableHttpCookie 與之前版本的區(qū)別是要將對 java.net.HttpCookie這個(gè)類的緩存處理換成對 okhttp3.Cookie 的處理，其他方面幾乎一樣。

廢話不多說了，直接上代碼
SerializableOkHttpCookies
主要做兩件事：將Cookie對象輸出為ObjectStream
將ObjectStream序列化成Cookie對象

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(jù)一定的規(guī)則去緩存或者獲取Cookie
SharedPreferences 存儲(chǔ)

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緩存到內(nèi)存中 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緩存到內(nèi)存中 如果緩存過期 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 序列化之后的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());
    }

    /**
     * 將字符串反序列化成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(jìn)制數(shù)組轉(zhuǎn)十六進(jìn)制字符串
     *
     * @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(jìn)制字符串轉(zhuǎn)二進(jìn)制數(shù)組
     *
     * @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持久化之后，就可以對Cookiejar進(jìn)行進(jìn)一步修改了，最終效果：

/** * 自動(dòng)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;
        }
    }

最后設(shè)置OkHttpClient

OkHttpClient.Builder builder = new OkHttpClient.Builder();
Cookiebuilder.cookieJar(new CookiesManager());
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