OkHttp3實現Cookies持續化管理

參考文章：

COOKIE和SESSION 是什麼？？？

1，由於HTTP協議是無狀態的協議，所以服務端需要記錄用戶的狀態時，就需要用某種機制來識具體的用戶，這個機制就是Session.典型的場景比如購物車，當你點擊下單按鈕時，由於HTTP協議無狀態，所以並不知道是哪個用戶操作的，所以服務端要爲特定的用戶創建了特定的Session，用於標識這個用戶，並且跟蹤用戶，這樣才知道購物車裏面有幾本書。這個Session是保存在服務端的，有一個唯一標識。在服務端保存Session的方法很多，內存、數據庫、文件都有。集羣的時候也要考慮Session的轉移，在大型的網站，一般會有專門的Session服務器集羣，用來保存用戶會話，這個時候 Session 信息都是放在內存的，使用一些緩存服務比如Memcached之類的來放 Session。

2，思考一下服務端如何識別特定的客戶？這個時候Cookie就登場了。每次HTTP請求的時候，客戶端都會發送相應的Cookie信息到服務端。實際上大多數的應用都是用 Cookie 來實現Session跟蹤的，第一次創建Session的時候，服務端會在HTTP協議中告訴客戶端，需要在 Cookie 裏面記錄一個Session ID，以後每次請求把這個會話ID發送到服務器，我就知道你是誰了。有人問，如果客戶端的瀏覽器禁用了 Cookie 怎麼辦？一般這種情況下，會使用一種叫做URL重寫的技術來進行會話跟蹤，即每次HTTP交互，URL後面都會被附加上一個諸如 sid=xxxxx 這樣的參數，服務端據此來識別用戶。

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，爲了更加自由定製化的cookie管理。其中 loadForRequest() 、 saveFromResponse() 這兩個方法最爲關鍵，分別是在發送時向request header中加入cookie，在接收時，讀取response header中的

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對象輸出爲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
根據一定的規則去緩存或者獲取Cookie
SharedPreferences 存儲

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;
}

/**
 * 二進制數組轉十六進制字符串
 *
 * @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);
}

/**
 * 十六進制字符串轉二進制數組
 *
 * @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;
    }
}

最後設置OkHttpClient
//持久化管理

Cookiebuilder.cookieJar(new CookiesManager());```

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我發現我特別想一個火影裏面的人物。。。。複製忍者哈哈哈哈

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