webview和okhttp实现session共享

服务器端通过session来得知连接的客户端，因此需要okhttp与webview使用一套cookie，就可以实现在H5页面中与原生app同步登陆。
通过阅读okhttp3源码得知，Okhttp是使用cookjar来设置cookie的，而在OKHttpClient的Builfer方法中.默认的cookjar是一个空的对象，没有设置任何cookie

/** 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();
}
};

所以只需要我们手动取得webview的cookie并设置在okhttp的cookJar上即可实现cookie的共享。webview是的引擎为webkit，在webkit是有cookieManager对cookie进行管理。

public class WebViewCookieHandler implements CookieJar {
private CookieManager mCookieManager = CookieManager.getInstance();

@Override
public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
    String urlString = url.toString();

    for (Cookie cookie : cookies) {
        mCookieManager.setCookie(urlString, cookie.toString());
    }
}

@Override
public List<Cookie> loadForRequest(HttpUrl url) {
    String urlString = url.toString();
    String cookiesString = mCookieManager.getCookie(urlString);

    if (cookiesString != null && !cookiesString.isEmpty()) {
        String[] cookieHeaders = cookiesString.split(";");
        List<Cookie> cookies = new ArrayList<>(cookieHeaders.length);

        for (String header : cookieHeaders) {
            cookies.add(Cookie.parse(url, header));
        }

        return cookies;
    }

    return Collections.emptyList();
  }
}

然后再创建okhttpclient的工具类中加上自定义的cookiejar

public static OKhttpClient getClient(){
      return new OkhttpClient.Builder()
                 .cookieJar(new WebViewCookieHandler())
                 .build();
}