https(安全超文本传输协议)与 http(超文本传输协议)相比，多了一层 SSL 认证，需要我们提供特定网点的证书才能访问 如果我们纯粹的用 HttpsURLConnection 去访问，则会报异常(使用不同的框架会导致所报的异常不同)

解决办法：

一、设置 HttpsURLConnection，让它信任所有证书(即跳过验证步骤)

二、为 HttpsURLConnection 添加一个所信任的证书

代码：

方法一：信任所有证书

public class GetUndoVerifyHttpsRequest {
  final static HostnameVerifier DO_NOT_VERIFY = new HostnameVerifier() {
    public boolean verify(String hostname, SSLSession session) {
      return true;
    } // 将所有验证的结果都设为true
  };

  public static String getStart(String urlString) throws Exception {
    HttpURLConnection httpURLConnection;
    HttpsURLConnection httpsURLConnection;

    URL url = new URL(urlString);
    trustAllHosts();
    httpsURLConnection = (HttpsURLConnection)url.openConnection();

    if (url.getProtocol().toLowerCase().equals("https")) {
      httpsURLConnection.setHostnameVerifier(DO_NOT_VERIFY);
      httpURLConnection = httpsURLConnection;
    } else { // 判断是https请求还是http请求
      httpURLConnection = (HttpURLConnection)url.openConnection();
    }
    httpURLConnection.setRequestMethod("GET");
    httpURLConnection.setReadTimeout(5000);

    if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
      InputStream inputStream = httpURLConnection.getInputStream();
      ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
      int len = 0;
      byte[] bytes = new byte[1024];
      while ((len = inputStream.read(bytes)) != -1) {
        byteArrayOutputStream.write(bytes, 0, len);
      }
      String values = new String(byteArrayOutputStream.toByteArray());
      inputStream.close();
      byteArrayOutputStream.close();

      return values;
    }
    return null;
  }

  /**
   * 不检查任何证书
   */
  private static void trustAllHosts() {
    final String TAG = "trustAllHosts";
    // 创建信任管理器
    TrustManager[] trustAllCerts = new TrustManager[] {new X509TrustManager(){

        public java.security.cert.X509Certificate[] getAcceptedIssuers(){
            return new java.security.cert.X509Certificate[] {};
  }

  public void checkClientTrusted(X509Certificate[] chain, String authType)
      throws CertificateException {
    Log.i(TAG, "checkClientTrusted");
  }

  public void checkServerTrusted(X509Certificate[] chain, String authType)
      throws CertificateException {
    Log.i(TAG, "checkServerTrusted");
  }
}
}
;

// Install the all-trusting trust manager
try {
  SSLContext sc = SSLContext.getInstance("TLS");
  sc.init(null, trustAllCerts, new java.security.SecureRandom());
  HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
} catch (Exception e) {
  e.printStackTrace();
}
}
}

方法二：添加证书验证

public class GetVerifyHttpsRequest {

private static TrustManagerFactory trustManagerFactory;

public static String getStart(String urlString, Context context) throws Exception {

    CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
    InputStream inputStreamCrt = context.getAssets().open("load-der.crt");//将你所导出的证书放入Assets文件中，在这里引用
    Certificate certificate = certificateFactory.generateCertificate(inputStreamCrt);

    KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
    keyStore.load(null, null);
    keyStore.setCertificateEntry("ca", certificate);

    String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
    trustManagerFactory = TrustManagerFactory.getInstance(tmfAlgorithm);
    trustManagerFactory.init(keyStore);

    getRequest(urlString);
    return tmfAlgorithm;
}

public static String getRequest(String urlString) throws Exception {
    HttpsURLConnection httpsURLConnection;

    SSLContext sslContext = SSLContext.getInstance("TLS");
    sslContext.init(null, trustManagerFactory.getTrustManagers(), null);
    URL url = new URL(urlString);

    httpsURLConnection = (HttpsURLConnection) url.openConnection();
    httpsURLConnection.setSSLSocketFactory(sslContext.getSocketFactory());
    httpsURLConnection.setRequestMethod("GET");
    httpsURLConnection.setReadTimeout(5000);

    if (httpsURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
        InputStream inputStream = httpsURLConnection.getInputStream();
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        int len = 0;
        byte[] bytes = new byte[1024];
        while ((len = inputStream.read(bytes)) != -1) {
            byteArrayOutputStream.write(bytes, 0, len);
        }
        String values = new String(byteArrayOutputStream.toByteArray());
        inputStream.close();
        byteArrayOutputStream.close();

        return values;
    }
    return null;
}
}

（附）：

public class GetNormalVerifyHttpRequest { public static String getStart(String urlString) throws Exception { HttpsURLConnection httpsURLConnection;

    URL url = new URL(urlString);//获取地址，将其转换成URL类
    httpsURLConnection = (HttpsURLConnection) url.openConnection();//通过地址拿到连接
    httpsURLConnection.setRequestMethod("GET");//设置请求方式（GET请求还是POST）
    httpsURLConnection.setReadTimeout(5000);//设置连接超时时间

    if (httpsURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
//如果返回码等于200，创建一个读入流来读取网络上的数据
        InputStream inputStream = httpsURLConnection.getInputStream();
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        int len = 0;
        byte[] bytes = new byte[1024];
        while ((len = inputStream.read(bytes)) != -1) {
            byteArrayOutputStream.write(bytes, 0, len);
        }//写入数据
        String values = new String(byteArrayOutputStream.toByteArray());//将所读到的数据通过String的构造方法放入values中，并关流返回
        inputStream.close();
        byteArrayOutputStream.close();

        return values;
    }
    return null;
}
}