android获取https证书

最近碰到一个问题， 有朋友问android这边能不能拿到服务器下发的证书，意思就是   自签名证书的https接口，在请求的时候，也没有添加自签名证书进信任列表，直接去发https请求，按照正常https步骤去理解，服务器会返回一个证书，这个证书由于客户端没有添加进信任列表，会导致https请求失败，提示没有找到信任的证书。  朋友疑问： 在服务器返回证书的时候，能不能强行信任呢？ 

针对这个问题， 我在这边做了测试：

1，由ca签发的ssl证书，部署一个服务

　　不设置请求的SSLSocketFactory，直接进行https请求

　　　　验证结果：ok

2，自签名的ssl证书，部署一个服务

　不设置请求的SSLSocketFactory，直接进行https请求

　　　　验证结果：error，报错信息   java.security.cert.CertPathValidatorException: Trust anchor for certification path not found，大体意思是没有找打信任的证书，也就是说这个证书没有被当前的请求对象所信任。

看报错信息是android系统已经封装好的证书校验规则。

但是如果不想本地预埋自签名证书，也不想让后台暴露证书下载的接口，该怎么办呢？

我这边提供一个比较简陋的方法，通过webview访问目标https地址，通过webview的onReceivedSslError方法，拿到SslError中的SslCertificate，然后再根据SslCertificate中的saveState方法获取Bundle，从bundle中拿到"x509-certificate"的字节数组，作为字节流读取流，通过通用的httpsutils，设置请求对象的sslsocketfactory。

代码如下：

package com.example.ajaxhttpsdemo;

import android.content.Context;
import android.net.http.SslCertificate;
import android.net.http.SslError;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.webkit.SslErrorHandler;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;

import javax.net.ssl.KeyManager;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

public class HttpsGetSSLSocketFactory {
    private static SslCertificate sslCertificate;
    public static class SSLParams {
        public SSLSocketFactory sSLSocketFactory;
        public X509TrustManager trustManager;
    }

    public interface Callback{
        void onSuccess(SSLParams sslParams);
        void onError(Exception e);
    }

    public static class MySSLException extends Exception{
        public MySSLException(String str) {
            super(str);
        }
    }

    public static void getSslSocketFactoryOnMainThread(Context context, String httpsUrl, final Callback callback){
        WebView webView = new WebView(context);
        webView.setWebViewClient(new WebViewClient(){
            @Override
            public void onReceivedSslError(WebView view, SslErrorHandler handler, SslError error) {
                sslCertificate = error.getCertificate();
                handler.proceed();
                if (sslCertificate!=null){
                    Bundle bundle = SslCertificate.saveState(sslCertificate);
                    byte[] byteArray = bundle.getByteArray("x509-certificate");//从bundle中拿出写入的x509证书
//                    byte[] byteArray = "123456".getBytes();//测试错误证书
                   if (byteArray!=null && byteArray.length>0){
                       try {
                           callback.onSuccess(getSslSocketFactory(new ByteArrayInputStream(byteArray)));
                       } catch (Exception e) {
                           callback.onError(e);
                       }
                   }
                }else {
                    callback.onError(new MySSLException("没有获取到服务器证书"));
                }
            }
        });
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);
        webView.loadUrl(httpsUrl);
    }

    private static SSLParams getSslSocketFactory(InputStream... certificates) throws Exception {
        SSLParams sslParams = new SSLParams();
        try {
            TrustManager[] trustManagers = prepareTrustManager(certificates);
            KeyManager[] keyManagers = prepareKeyManager(null, null);
            SSLContext sslContext = SSLContext.getInstance("TLS");
            X509TrustManager trustManager;
            if (trustManagers != null) {
                trustManager = new MyTrustManager(
                        chooseTrustManager(trustManagers));
            } else {
                throw new Exception("证书错误");
            }
            sslContext.init(keyManagers,
                    new TrustManager[]{trustManager}, null);
            sslParams.sSLSocketFactory = sslContext.getSocketFactory();
            sslParams.trustManager = trustManager;
            return sslParams;
        } catch (NoSuchAlgorithmException e) {
            throw new AssertionError(e);
        } catch (KeyManagementException e) {
            throw new AssertionError(e);
        } catch (KeyStoreException e) {
            throw new AssertionError(e);
        } catch (Exception e) {
            throw e;
        }
    }
    private static X509TrustManager chooseTrustManager(
            TrustManager[] trustManagers) {
        for (TrustManager trustManager : trustManagers) {
            if (trustManager instanceof X509TrustManager) {
                return (X509TrustManager) trustManager;
            }
        }
        return null;
    }
    private static TrustManager[] prepareTrustManager(
            InputStream... certificates) {
        if (certificates == null || certificates.length <= 0)
            return null;
        try {
            CertificateFactory certificateFactory = CertificateFactory
                    .getInstance("X.509");
            KeyStore keyStore = KeyStore.getInstance(KeyStore
                    .getDefaultType());
            keyStore.load(null);
            int index = 0;
            for (InputStream certificate : certificates) {
                String certificateAlias = Integer.toString(index++);
                keyStore.setCertificateEntry(certificateAlias,
                        certificateFactory.generateCertificate(certificate));
                try {
                    if (certificate != null)
                        certificate.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            TrustManagerFactory trustManagerFactory;
            trustManagerFactory = TrustManagerFactory
                    .getInstance(TrustManagerFactory.getDefaultAlgorithm());
            trustManagerFactory.init(keyStore);
            return trustManagerFactory.getTrustManagers();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    private static KeyManager[] prepareKeyManager(InputStream bksFile,
                                                  String password) {
        try {
            if (bksFile == null || password == null)
                return null;
            KeyStore clientKeyStore = KeyStore.getInstance("PKCS12");
            clientKeyStore.load(bksFile, password.toCharArray());
            KeyManagerFactory keyManagerFactory = KeyManagerFactory
                    .getInstance(KeyManagerFactory.getDefaultAlgorithm());
            keyManagerFactory.init(clientKeyStore, password.toCharArray());
            return keyManagerFactory.getKeyManagers();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    private static class MyTrustManager implements X509TrustManager {
        private X509TrustManager defaultTrustManager;
        private X509TrustManager localTrustManager;

        public MyTrustManager(X509TrustManager localTrustManager)
                throws NoSuchAlgorithmException, KeyStoreException {
            TrustManagerFactory var4 = TrustManagerFactory
                    .getInstance(TrustManagerFactory.getDefaultAlgorithm());
            var4.init((KeyStore) null);
            defaultTrustManager = chooseTrustManager(var4
                    .getTrustManagers());
            this.localTrustManager = localTrustManager;
        }

        @Override
        public void checkClientTrusted(X509Certificate[] chain,
                                       String authType) throws CertificateException {
        }

        @Override
        public void checkServerTrusted(X509Certificate[] chain,
                                       String authType) throws CertificateException {
            try {
                defaultTrustManager.checkServerTrusted(chain, authType);
            } catch (CertificateException ce) {
                localTrustManager.checkServerTrusted(chain, authType);
            }
        }

        @Override
        public X509Certificate[] getAcceptedIssuers() {
            return new X509Certificate[0];
        }
    }
}

　　

留作备用，有错误再更正