呼叫new CustomTrust() 即可產生OkHttpClient

關鍵點：
1、將pem證書放入Raw或者assets目錄。
2、證書的KeyStore讀取方式。
3、HostnameVerifier過濾驗證。

講解： Pem 有多個 Certificate ，用CertificateFactory 讀取 inputstream 為context.getResources().openRawResource(R.raw.a223)

1、證書讀取詳細：

   private SSLContext trustManagerForCertificates(InputStream in)
          throws
 
 GeneralSecurityException, IOException {
    CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
    Collection<? extends Certificate> certificates = certificateFactory.generateCertificates(in);
    if (certificates.isEmpty()) {
      throw new IllegalArgumentException("expected non-empty set of trusted certificates"
 
);
    }

    // Put the certificates a key store.
    char[] password = CLIENT_KET_PASSWORD.toCharArray(); // Any password will work.
    KeyStore keyStore = newEmptyKeyStore(password);
    int index = 0;
    for (Certificate certificate : certificates) {
      String certificateAlias = Integer.toString(index++);
      keyStore.setCertificateEntry(certificateAlias, certificate);
    }

  //  keyStore.load(in,CLIENT_KET_PASSWORD.toCharArray());
 

    // Use it to build an X509 trust manager.
    KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance(
        KeyManagerFactory.getDefaultAlgorithm());
    keyManagerFactory.init(keyStore, password);
    TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(
        TrustManagerFactory.getDefaultAlgorithm());
    trustManagerFactory.init(keyStore);
    TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
    if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager)) {
      throw new IllegalStateException("Unexpected default trust managers:"
          + Arrays.toString(trustManagers));
    }

    SSLContext ssContext = SSLContext.getInstance("SSL");
    ssContext.init(keyManagerFactory.getKeyManagers(),trustManagers,null);
    //return (X509TrustManager) trustManagers[0];
    return  ssContext;
  }


  private KeyStore newEmptyKeyStore(char[] password) throws GeneralSecurityException {
    try {
      KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
      InputStream in = null; // By convention, 'null' creates an empty key store.
      keyStore.load(in, password);
      return keyStore;
    } catch (IOException e) {
      throw new AssertionError(e);
    }
  }

2、SSLContext建立

關鍵：必須重寫 HostnameVerifier 不然會出現javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated.錯誤，因為OKhttp 擁有預設的驗證。

try {
    //  trustManager = trustManagerForCertificates(trustedCertificatesInputStream());
      SSLContext sslContext =  trustManagerForCertificates(trustedCertificatesInputStream()); //SSLContext.getInstance("TLS");
      sslSocketFactory = sslContext.getSocketFactory();
    } catch (GeneralSecurityException e) {
      throw new RuntimeException(e);
    } catch (IOException e) {
      e.printStackTrace();
    }
    client = new OkHttpClient.Builder()
        .sslSocketFactory(sslSocketFactory).hostnameVerifier(new HostnameVerifier() {
              @Override
              public boolean verify(String hostname, SSLSession session) {
                return true;
              }
            })
        .build();

所有程式碼：將證書路徑改動一下就可以直接使用了

import android.content.Context;

import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.KeyStore;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.util.Arrays;
import java.util.Collection;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

import okhttp3.CertificatePinner;
import okhttp3.OkHttpClient;

public final class CustomTrust {
  public static final String tag = "CustomTrust";
  private static final String CLIENT_KET_PASSWORD = "2342342342344433";
  public final OkHttpClient client;
  Context context;
  public CustomTrust(Context context)  {
    this.context = context;
    X509TrustManager trustManager;
    SSLSocketFactory sslSocketFactory=null;

    try {
    //  trustManager = trustManagerForCertificates(trustedCertificatesInputStream());
      SSLContext sslContext =  trustManagerForCertificates(trustedCertificatesInputStream()); //SSLContext.getInstance("TLS");
      sslSocketFactory = sslContext.getSocketFactory();
    } catch (GeneralSecurityException e) {
      throw new RuntimeException(e);
    } catch (IOException e) {
      e.printStackTrace();
    }
    client = new OkHttpClient.Builder()
        .sslSocketFactory(sslSocketFactory).hostnameVerifier(new HostnameVerifier() {
              @Override
              public boolean verify(String hostname, SSLSession session) {
                return true;
              }
            })
        .build();

  }


  /**
   * Returns an input stream containing one or more certificate PEM files. This implementation just
   * embeds the PEM files in Java strings; most applications will instead read this from a resource
   * file that gets bundled with the application.
   */
  private InputStream trustedCertificatesInputStream() {
    // PEM files for root certificates of Comodo and Entrust. These two CAs are sufficient to view
    // https://publicobject.com (Comodo) and https://squareup.com (Entrust). But they aren't
    // sufficient to connect to most HTTPS sites including https://godaddy.com and https://visa.com.
    // Typically developers will need to get a PEM file from their organization's TLS administrator.

    return context.getResources().openRawResource(R.raw.qwww2) ;

    /*return new Buffer()
        .writeUtf8(comodoRsaCertificationAuthority)
        .writeUtf8(entrustRootCertificateAuthority)
        .inputStream();*/
  }

  /**
   * Returns a trust manager that trusts {@code certificates} and none other. HTTPS services whose
   * certificates have not been signed by these certificates will fail with a {@code
   * SSLHandshakeException}.
   *
   * <p>This can be used to replace the host platform's built-in trusted certificates with a custom
   * set. This is useful in development where certificate authority-trusted certificates aren't
   * available. Or in production, to avoid reliance on third-party certificate authorities.
   *
   * <p>See also {@link CertificatePinner}, which can limit trusted certificates while still using
   * the host platform's built-in trust store.
   *
   * <h3>Warning: Customizing Trusted Certificates is Dangerous!</h3>
   *
   * <p>Relying on your own trusted certificates limits your server team's ability to update their
   * TLS certificates. By installing a specific set of trusted certificates, you take on additional
   * operational complexity and limit your ability to migrate between certificate authorities. Do
   * not use custom trusted certificates in production without the blessing of your server's TLS
   * administrator.
   */
  private SSLContext trustManagerForCertificates(InputStream in)
          throws GeneralSecurityException, IOException {
    CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
    Collection<? extends Certificate> certificates = certificateFactory.generateCertificates(in);
    if (certificates.isEmpty()) {
      throw new IllegalArgumentException("expected non-empty set of trusted certificates");
    }

    // Put the certificates a key store.
    char[] password = CLIENT_KET_PASSWORD.toCharArray(); // Any password will work.
    KeyStore keyStore = newEmptyKeyStore(password);
    int index = 0;
    for (Certificate certificate : certificates) {
      String certificateAlias = Integer.toString(index++);
      keyStore.setCertificateEntry(certificateAlias, certificate);
    }

  //  keyStore.load(in,CLIENT_KET_PASSWORD.toCharArray());
    // Use it to build an X509 trust manager.
    KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance(
        KeyManagerFactory.getDefaultAlgorithm());
    keyManagerFactory.init(keyStore, password);
    TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(
        TrustManagerFactory.getDefaultAlgorithm());
    trustManagerFactory.init(keyStore);
    TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
    if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager)) {
      throw new IllegalStateException("Unexpected default trust managers:"
          + Arrays.toString(trustManagers));
    }

    SSLContext ssContext = SSLContext.getInstance("SSL");
    ssContext.init(keyManagerFactory.getKeyManagers(),trustManagers,null);
    //return (X509TrustManager) trustManagers[0];
    return  ssContext;
  }

  private KeyStore newEmptyKeyStore(char[] password) throws GeneralSecurityException {
    try {
      KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
      InputStream in = null; // By convention, 'null' creates an empty key store.
      keyStore.load(in, password);
      return keyStore;
    } catch (IOException e) {
      throw new AssertionError(e);
    }
  }

//  public static void main(String... args) throws Exception {
//    new CustomTrust().run();
//  }
}