Android端WEEX + HTTPDNS 最佳实践

由于WebView并未暴露处设置DNS的接口，因而在WebView场景下使用HttpDns存在很多无法限制，但如果接入WEEX,则可以较好地植入HTTPDNS，本文主要介绍在WEEX场景下接入HTTPDNS的方案细节。

在WEEX运行时环境下，所有的逻辑最终都会转换到Native Runtime中执行，网络请求也不例外。同时WEEX也提供了自定义相应实现的接口，通过重写网络请求适配器，我们可以较为简单地接入HTTPDNS。在WEEX运行环境中，主要有两种网络请求：

• 通过Stream进行的网络请求
• 标签指定的加载图片的网络请求

1 Stream网络请求 + HTTPDNS

Stream网络请求在Android端最终会通过DefaultWXHttpAdapter完成，同时WEEX也提供了相应的接口自定义网络请求适配器。具体的逻辑如下：

第一步：创建自定义网络请求适配器，实现IWXHttpAdapter接口

public class WXHttpdnsAdatper implements IWXHttpAdapter {
      @Override
    public void sendRequest(final WXRequest request, final OnHttpListener listener) {
      ......
    }
}

该接口需要实现sendRequest方法，该方法传入一个WXRequest对象的实例，该对象提供了以下信息：

public class WXRequest {
  // The request parameter
  public Map<String, String> paramMap;
  // The request URL
  public String url;
  // The request method
  public String method;
  // The request body
  public String body;
  // The request time out
  public int timeoutMs = WXRequest.DEFAULT_TIMEOUT_MS;
  // The default timeout
  public static final int DEFAULT_TIMEOUT_MS = 3000;
}

通过该对象我们可以获取到请求报头、URL、方法以及body。

第二步：在WEEX初始化时注册自定义网络适配器，替换默认适配器：

InitConfig config=new InitConfig.Builder()
                .setHttpAdapter(new WXHttpdnsAdatper()) // 注册自定义网络请求适配器
                  ......
                .build();
        WXSDKEngine.initialize(this,config);

之后左右的网络请求都会通过WXHttpdnsAdatper实现，所以只需要在WXHttpdnsAdapter中植入HTTPDNS逻辑即可，具体逻辑可以参考如下代码：

public class WXHttpdnsAdatper implements IWXHttpAdapter {
  ......
    private void execute(Runnable runnable){
        if(mExecutorService==null){
            mExecutorService = Executors.newFixedThreadPool(3);
        }
        mExecutorService.execute(runnable);
    }

    @Override
    public void sendRequest(final WXRequest request, final OnHttpListener listener) {
        if (listener != null) {
            listener.onHttpStart();
        }

        Log.e(TAG, "URL:" + request.url);
        execute(new Runnable() {
            @Override
            public void run() {
                WXResponse response = new WXResponse();
                WXHttpdnsAdatper.IEventReporterDelegate reporter = getEventReporterDelegate();
                try {
                      // 创建连接
                    HttpURLConnection connection = openConnection(request, listener);
                    reporter.preConnect(connection, request.body);
                  ......
                } catch (IOException |IllegalArgumentException e) {
                  ......
                }
            }
        });
    }

    private HttpURLConnection openConnection(WXRequest request, OnHttpListener listener) throws IOException {
        URL url = new URL(request.url);
          // 创建一个植入HTTPDNS的连接
        HttpURLConnection connection = openHttpDnsConnection(request, request.url, listener, null);
        return connection;
    }



    private HttpURLConnection openHttpDnsConnection(WXRequest request, String path, OnHttpListener listener, String reffer) {
        HttpURLConnection conn = null;
        URL url = null;
        try {
            url = new URL(path);
            conn = (HttpURLConnection) url.openConnection();
           // 创建一个接入httpdns的连接
            HttpURLConnection tmpConn = httpDnsConnection(url, path);
          ......

            int code = conn.getResponseCode();// Network block
            Log.e(TAG, "code:" + code);
            // SNI场景下通常涉及重定向，重新建立新连接
            if (needRedirect(code)) {
                Log.e(TAG, "need redirect");
                String location = conn.getHeaderField("Location");
                if (location == null) {
                    location = conn.getHeaderField("location");
                }

                if (location != null) {
                    if (!(location.startsWith("http://") || location
                            .startsWith("https://"))) {
                        //某些时候会省略host，只返回后面的path，所以需要补全url
                        URL originalUrl = new URL(path);
                        location = originalUrl.getProtocol() + "://"
                                + originalUrl.getHost() + location;
                    }
                    Log.e(TAG, "code:" + code + "; location:" + location + "; path" + path);
                    return openHttpDnsConnection(request, location, listener, path);
                } else {
                    return conn;
                }
            } else {
                // redirect finish.
                Log.e(TAG, "redirect finish");
                return conn;
            }
        }
        ......
        return conn;
    }

    private HttpURLConnection httpDnsConnection(URL url, String path) {
        HttpURLConnection conn = null;
        // 通过HTTPDNS SDK接口获取IP
        String ip = HttpDnsManager.getInstance().getHttpDnsService().getIpByHostAsync(url.getHost());
        if (ip != null) {
            // 通过HTTPDNS获取IP成功，进行URL替换和HOST头设置
            Log.d(TAG, "Get IP: " + ip + " for host: " + url.getHost() + " from HTTPDNS successfully!");
            String newUrl = path.replaceFirst(url.getHost(), ip);
            try {
                conn = (HttpURLConnection) new URL(newUrl).openConnection();
            } catch (IOException e) {
                return null;
            }

            // 设置HTTP请求头Host域
            conn.setRequestProperty("Host", url.getHost());

            // HTTPS场景
            if (conn instanceof HttpsURLConnection) {
                final HttpsURLConnection httpsURLConnection = (HttpsURLConnection)conn;
                WXTlsSniSocketFactory sslSocketFactory = new WXTlsSniSocketFactory((HttpsURLConnection) conn);

                // SNI场景，创建SSLScocket解决SNI场景下的证书问题
                conn.setInstanceFollowRedirects(false);
                httpsURLConnection.setSSLSocketFactory(sslSocketFactory);
                // HTTPS场景，证书校验
                httpsURLConnection.setHostnameVerifier(new HostnameVerifier() {
                    @Override
                    public boolean verify(String hostname, SSLSession session) {
                        String host = httpsURLConnection.getRequestProperty("Host");
                        Log.e(TAG, "verify host:" + host);
                        if (null == host) {
                            host = httpsURLConnection.getURL().getHost();
                        }
                        return HttpsURLConnection.getDefaultHostnameVerifier().verify(host, session);
                    }
                });
            }
        } else {
            Log.e(TAG, "no corresponding ip found, return null");
            return null;
        }

        return conn;
    }
}

1.2 <image>网络请求 + HTTPDNS

WEEX并没有提供默认的图片适配器实现，所以用户必须自行实现才能完成图片请求逻辑，具体步骤分为以下几步：

第一步：自定义图片请求适配器，实现IWXImgLoaderAdapter接口

public class HttpDnsImageAdapter implements IWXImgLoaderAdapter {
    @Override
    public void setImage(final String url, final ImageView view, WXImageQuality quality, final WXImageStrategy strategy) {
      ......
    }
}

第二步：在WEEX初始化时注册该图片适配器：

    private void initWeex() {
        InitConfig config=new InitConfig.Builder()
                .setImgAdapter(new HttpDnsImageAdapter())
                .build();
        WXSDKEngine.initialize(this,config);
          ......
    }

所以同WXHttpdnsAdatper一样，我们只需在HttpDnsImageAdapter植入HTTPDNS逻辑即可。具体代码可参考：

/**
 * Created by liyazhou on 2017/10/22.
 */

public class WXHttpDnsImageAdapter implements IWXImgLoaderAdapter {
  
    @Override
    public void setImage(final String url, final ImageView view, WXImageQuality quality, final WXImageStrategy strategy) {
        Log.e(TAG, "img url:" + url);
        execute(new Runnable() {
            @Override
            public void run() {
              ......
                HttpURLConnection conn = null;
                try {
                     conn = createConnection(url);
                     ....
                     // 将得到的数据转化成InputStream
                     InputStream is = conn.getInputStream();
                     // 将InputStream转换成Bitmap
                     final Bitmap bitmap = BitmapFactory.decodeStream(is);
                     WXSDKManager.getInstance().postOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            view.setImageBitmap(bitmap);
                        }
                     }, 0);
                      ......
            }
        });
    }

    protected HttpURLConnection createConnection(String originalUrl) throws IOException {
        mHttpDnsService = HttpDnsManager.getInstance().getHttpDnsService();
        if (mHttpDnsService == null) {
            URL url = new URL(originalUrl);
            return (HttpURLConnection) url.openConnection();
        } else {
            return httpDnsRequest(originalUrl, null);
        }
    }

    private HttpURLConnection httpDnsRequest(String path, String reffer) {
        HttpURLConnection httpDnsConn = null;
        HttpURLConnection originalConn = null;
        URL url = null;
        try {
            url = new URL(path);
            originalConn = (HttpURLConnection) url.openConnection();
            // 异步接口获取IP
            String ip = HttpDnsManager.getInstance().getHttpDnsService().getIpByHostAsync(url.getHost());
            if (ip != null) {
                // 通过HTTPDNS获取IP成功，进行URL替换和HOST头设置
                Log.d(TAG, "Get IP: " + ip + " for host: " + url.getHost() + " from HTTPDNS successfully!");
                String newUrl = path.replaceFirst(url.getHost(), ip);
                httpDnsConn = (HttpURLConnection) new URL(newUrl).openConnection();

                // 设置HTTP请求头Host域
                httpDnsConn.setRequestProperty("Host", url.getHost());

                // HTTPS场景
                if (httpDnsConn instanceof HttpsURLConnection) {
                    final HttpsURLConnection httpsURLConnection = (HttpsURLConnection)httpDnsConn;
                    WXTlsSniSocketFactory sslSocketFactory = new WXTlsSniSocketFactory((HttpsURLConnection) httpDnsConn);

                    // sni场景，创建SSLScocket解决SNI场景下的证书问题
                    httpsURLConnection.setSSLSocketFactory(sslSocketFactory);
                    // https场景，证书校验
                    httpsURLConnection.setHostnameVerifier(new HostnameVerifier() {
                        @Override
                        public boolean verify(String hostname, SSLSession session) {
                            String host = httpsURLConnection.getRequestProperty("Host");
                            if (null == host) {
                                host = httpsURLConnection.getURL().getHost();
                            }
                            return HttpsURLConnection.getDefaultHostnameVerifier().verify(host, session);
                        }
                    });
                }
            } else {
                return originalConn;
            }

          ......

            int code = httpDnsConn.getResponseCode();// Network block
            if (needRedirect(code)) {
                String location = httpDnsConn.getHeaderField("Location");
                if (location == null) {
                    location = httpDnsConn.getHeaderField("location");
                }

                if (location != null) {
                    if (!(location.startsWith("http://") || location
                            .startsWith("https://"))) {
                        //某些时候会省略host，只返回后面的path，所以需要补全url
                        URL originalUrl = new URL(path);
                        location = originalUrl.getProtocol() + "://"
                                + originalUrl.getHost() + location;
                    }
                    Log.e(TAG, "code:" + code + "; location:" + location + "; path" + path);
                    return httpDnsRequest(location, path);
                } else {
                    return originalConn;
                }
            }
        return originalConn;
    }
}

上述方案详细代码建：WeexAndroid