Android OkHttp的Cookie自己主动化管理

Android中在使用OkHttp这个库的时候。有时候须要持久化Cookie，那么怎么实现呢。OkHttp的内部源代码过于复杂，不进行深究。这里仅仅看当中的HttpEngineer里面的部分源代码，在发起请求以及请求结束都会调用这个类的几个方法。

我们先看networkRequest方法。在里面通过client.getCookieHandler()函数获得了CookieHandler对象。通过该对象拿到cookie并设置到请求头里，请求结束后取得响应后通过networkResponse.headers()函数将请求头获得传入receiveHeaders函数，并将取得的cookie存入getCookieHandler得到的一个CookieHandler对象中去

/**
 * Populates request with defaults and cookies.
 *
 * <p>This client doesn't specify a default {@code Accept} header because it
 * doesn't know what content types the application is interested in.
 */
private Request networkRequest(Request request) throws IOException {
  Request.Builder result = request.newBuilder();

  //此处省略n行代码......

  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);
  }

  //此处省略n行代码......

  return result.build();
}

public void readResponse() throws IOException {
  //此处省略n行代码......

  receiveHeaders(networkResponse.headers());

  //此处省略n行代码......
}

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

而这个CookieHandler对象是OkHttpClient类中的一个属性，提供了getter和setter方法，默认的构造函数OkHttpClient client = new OkHttpClient();不会创建这个CookieHandler对象。如果我们传入了这个对象。那么OkHttp自然会进行cookie的自己主动管理了。

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

public CookieHandler getCookieHandler() {
  return cookieHandler;
}

那么如果我们将CookieHandler对象传入

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

那么，如今关键是怎样去实现这个CookieHandler 对象。CookieManager是CookieHandler 的一个子类，其构造函数 public CookieManager(CookieStore store, CookiePolicy cookiePolicy)须要传入两个參数，CookieStore 是一个接口，因此我们实现CookieStore接口中的抽象方法。就可以实现这个CookieHandler 对象。

參考android-async-http这个库，它具有cookie的自己主动管理功能。主要我们參考当中的两个类

• PersistentCookieStore
• SerializableCookie

參考以上两个类并做适当改动，得到了例如以下两个类，他们的功能就是将cookie保持在SharedPreferences中。

package com.kltz88.okhttp.cookie;

/**
 * User:lizhangqu(513163535@qq.com)
 * Date:2015-07-13
 * Time: 17:31
 */
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.net.HttpCookie;

public class SerializableHttpCookie implements Serializable {
    private static final long serialVersionUID = 6374381323722046732L;

    private transient final HttpCookie cookie;
    private transient HttpCookie clientCookie;

    public SerializableHttpCookie(HttpCookie cookie) {
        this.cookie = cookie;
    }

    public HttpCookie getCookie() {
        HttpCookie bestCookie = cookie;
        if (clientCookie != null) {
            bestCookie = clientCookie;
        }
        return bestCookie;
    }

    private void writeObject(ObjectOutputStream out) throws IOException {
        out.writeObject(cookie.getName());
        out.writeObject(cookie.getValue());
        out.writeObject(cookie.getComment());
        out.writeObject(cookie.getCommentURL());
        out.writeObject(cookie.getDomain());
        out.writeLong(cookie.getMaxAge());
        out.writeObject(cookie.getPath());
        out.writeObject(cookie.getPortlist());
        out.writeInt(cookie.getVersion());
        out.writeBoolean(cookie.getSecure());
        out.writeBoolean(cookie.getDiscard());
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        String name = (String) in.readObject();
        String value = (String) in.readObject();
        clientCookie = new HttpCookie(name, value);
        clientCookie.setComment((String) in.readObject());
        clientCookie.setCommentURL((String) in.readObject());
        clientCookie.setDomain((String) in.readObject());
        clientCookie.setMaxAge(in.readLong());
        clientCookie.setPath((String) in.readObject());
        clientCookie.setPortlist((String) in.readObject());
        clientCookie.setVersion(in.readInt());
        clientCookie.setSecure(in.readBoolean());
        clientCookie.setDiscard(in.readBoolean());
    }
}

package com.kltz88.okhttp.cookie;

/**
 * User:lizhangqu(513163535@qq.com)
 * Date:2015-07-13
 * Time: 17:31
 */
import android.content.Context;
import android.content.SharedPreferences;
import android.text.TextUtils;
import android.util.Log;

import java.io.*;
import java.net.CookieStore;
import java.net.HttpCookie;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;

/**
 * A persistent cookie store which implements the Apache HttpClient CookieStore interface.
 * Cookies are stored and will persist on the user's device between application sessions since they
 * are serialized and stored in SharedPreferences. Instances of this class are
 * designed to be used with AsyncHttpClient#setCookieStore, but can also be used with a
 * regular old apache HttpClient/HttpContext if you prefer.
 */
public class PersistentCookieStore implements CookieStore {

    private static final String LOG_TAG = "PersistentCookieStore";
    private static final String COOKIE_PREFS = "CookiePrefsFile";
    private static final String COOKIE_NAME_PREFIX = "cookie_";

    private final HashMap<String, ConcurrentHashMap<String, HttpCookie>> cookies;
    private final SharedPreferences cookiePrefs;

    /**
     * Construct a persistent cookie store.
     *
     * @param context Context to attach cookie store to
     */
    public PersistentCookieStore(Context context) {
        cookiePrefs = context.getSharedPreferences(COOKIE_PREFS, 0);
        cookies = new HashMap<String, ConcurrentHashMap<String, HttpCookie>>();

        // Load any previously stored cookies into the store
        Map<String, ?> prefsMap = cookiePrefs.getAll();
        for(Map.Entry<String, ?
> entry : prefsMap.entrySet()) {
            if (((String)entry.getValue()) != null && !((String)entry.getValue()).startsWith(COOKIE_NAME_PREFIX)) {
                String[] cookieNames = TextUtils.split((String)entry.getValue(), ",");
                for (String name : cookieNames) {
                    String encodedCookie = cookiePrefs.getString(COOKIE_NAME_PREFIX + name, null);
                    if (encodedCookie != null) {
                        HttpCookie decodedCookie = decodeCookie(encodedCookie);
                        if (decodedCookie != null) {
                            if(!cookies.containsKey(entry.getKey()))
                                cookies.put(entry.getKey(), new ConcurrentHashMap<String, HttpCookie>());
                            cookies.get(entry.getKey()).put(name, decodedCookie);
                        }
                    }
                }

            }
        }
    }

    @Override
    public void add(URI uri, HttpCookie cookie) {
        String name = getCookieToken(uri, cookie);

        // Save cookie into local store, or remove if expired
        if (!cookie.hasExpired()) {
            if(!cookies.containsKey(uri.getHost()))
                cookies.put(uri.getHost(), new ConcurrentHashMap<String, HttpCookie>());
            cookies.get(uri.getHost()).put(name, cookie);
        } else {
            if(cookies.containsKey(uri.toString()))
                cookies.get(uri.getHost()).remove(name);
        }

        // Save cookie into persistent store
        SharedPreferences.Editor prefsWriter = cookiePrefs.edit();
        prefsWriter.putString(uri.getHost(), TextUtils.join(",", cookies.get(uri.getHost()).keySet()));
        prefsWriter.putString(COOKIE_NAME_PREFIX + name, encodeCookie(new SerializableHttpCookie(cookie)));
        prefsWriter.commit();
    }

    protected String getCookieToken(URI uri, HttpCookie cookie) {
        return cookie.getName() + cookie.getDomain();
    }

    @Override
    public List<HttpCookie> get(URI uri) {
        ArrayList<HttpCookie> ret = new ArrayList<HttpCookie>();
        if(cookies.containsKey(uri.getHost()))
            ret.addAll(cookies.get(uri.getHost()).values());
        return ret;
    }

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


    @Override
    public boolean remove(URI uri, HttpCookie cookie) {
        String name = getCookieToken(uri, cookie);

        if(cookies.containsKey(uri.getHost()) && cookies.get(uri.getHost()).containsKey(name)) {
            cookies.get(uri.getHost()).remove(name);

            SharedPreferences.Editor prefsWriter = cookiePrefs.edit();
            if(cookiePrefs.contains(COOKIE_NAME_PREFIX + name)) {
                prefsWriter.remove(COOKIE_NAME_PREFIX + name);
            }
            prefsWriter.putString(uri.getHost(), TextUtils.join(",", cookies.get(uri.getHost()).keySet()));
            prefsWriter.commit();

            return true;
        } else {
            return false;
        }
    }

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

        return ret;
    }

    @Override
    public List<URI> getURIs() {
        ArrayList<URI> ret = new ArrayList<URI>();
        for (String key : cookies.keySet())
            try {
                ret.add(new URI(key));
            } catch (URISyntaxException e) {
                e.printStackTrace();
            }

        return ret;
    }

    /**
     * Serializes Cookie object into String
     *
     * @param cookie cookie to be encoded, can be null
     * @return cookie encoded as String
     */
    protected String encodeCookie(SerializableHttpCookie 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());
    }

    /**
     * Returns cookie decoded from cookie string
     *
     * @param cookieString string of cookie as returned from http request
     * @return decoded cookie or null if exception occured
     */
    protected HttpCookie decodeCookie(String cookieString) {
        byte[] bytes = hexStringToByteArray(cookieString);
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes);
        HttpCookie cookie = null;
        try {
            ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
            cookie = ((SerializableHttpCookie) objectInputStream.readObject()).getCookie();
        } catch (IOException e) {
            Log.d(LOG_TAG, "IOException in decodeCookie", e);
        } catch (ClassNotFoundException e) {
            Log.d(LOG_TAG, "ClassNotFoundException in decodeCookie", e);
        }

        return cookie;
    }

    /**
     * Using some super basic byte array &lt;-&gt; hex conversions so we don't have to rely on any
     * large Base64 libraries. Can be overridden if you like!
     *
     * @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);
    }

    /**
     * Converts hex values from strings to byte arra
     *
     * @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;
    }


}

使用的时候。在发起请求前对CookieHandler进行设置，兴许的cookie全都是自己主动管理，无需你关心cookie的保存于读取

OkHttpClient client = new OkHttpClient();

client.setCookieHandler(new CookieManager(
        new PersistentCookieStore(getApplicationContext()),
        CookiePolicy.ACCEPT_ALL));

这样，实现模拟登录，抓取一些数据就方便非常多了。再也不用手动处理cookie了。