接受的答案需要选项3

也 选项2很糟糕。绝对不应该使用它(特别是在生产中)，因为它提供了一种虚假的安全感。只需使用HTTP而不是选项2。

选项3

使用自签名证书进行Https连接。

这里有一个例子:

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManagerFactory;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.URL;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.KeyStore;

/*
 * Use a SSLSocket to send a HTTP GET request and read the response from an HTTPS server.
 * It assumes that the client is not behind a proxy/firewall
 */

public class SSLSocketClientCert
{
    private static final String[] useProtocols = new String[] {"TLSv1.2"};
    public static void main(String[] args) throws Exception
    {
        URL inputUrl = null;
        String certFile = null;
        if(args.length < 1)
        {
            System.out.println("Usage: " + SSLSocketClient.class.getName() + " <url>");
            System.exit(1);
        }
        if(args.length == 1)
        {
            inputUrl = new URL(args[0]);
        }
        else
        {
            inputUrl = new URL(args[0]);
            certFile = args[1];
        }
        SSLSocket sslSocket = null;
        PrintWriter outWriter = null;
        BufferedReader inReader = null;
        try
        {
            SSLSocketFactory sslSocketFactory = getSSLSocketFactory(certFile);

            sslSocket = (SSLSocket) sslSocketFactory.createSocket(inputUrl.getHost(), inputUrl.getPort() == -1 ? inputUrl.getDefaultPort() : inputUrl.getPort());
            String[] enabledProtocols = sslSocket.getEnabledProtocols();
            System.out.println("Enabled Protocols: ");
            for(String enabledProtocol : enabledProtocols) System.out.println("\t" + enabledProtocol);

            String[] supportedProtocols = sslSocket.getSupportedProtocols();
            System.out.println("Supported Protocols: ");
            for(String supportedProtocol : supportedProtocols) System.out.println("\t" + supportedProtocol + ", ");

            sslSocket.setEnabledProtocols(useProtocols);

            /*
             * Before any data transmission, the SSL socket needs to do an SSL handshake.
             * We manually initiate the handshake so that we can see/catch any SSLExceptions.
             * The handshake would automatically  be initiated by writing & flushing data but
             * then the PrintWriter would catch all IOExceptions (including SSLExceptions),
             * set an internal error flag, and then return without rethrowing the exception.
             *
             * This means any error messages are lost, which causes problems here because
             * the only way to tell there was an error is to call PrintWriter.checkError().
             */
            sslSocket.startHandshake();
            outWriter = sendRequest(sslSocket, inputUrl);
            readResponse(sslSocket);
            closeAll(sslSocket, outWriter, inReader);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            closeAll(sslSocket, outWriter, inReader);
        }
    }

    private static PrintWriter sendRequest(SSLSocket sslSocket, URL inputUrl) throws IOException
    {
        PrintWriter outWriter = new PrintWriter(new BufferedWriter(new OutputStreamWriter(sslSocket.getOutputStream())));
        outWriter.println("GET " + inputUrl.getPath() + " HTTP/1.1");
        outWriter.println("Host: " + inputUrl.getHost());
        outWriter.println("Connection: Close");
        outWriter.println();
        outWriter.flush();
        if(outWriter.checkError())        // Check for any PrintWriter errors
            System.out.println("SSLSocketClient: PrintWriter error");
        return outWriter;
    }

    private static void readResponse(SSLSocket sslSocket) throws IOException
    {
        BufferedReader inReader = new BufferedReader(new InputStreamReader(sslSocket.getInputStream()));
        String inputLine;
        while((inputLine = inReader.readLine()) != null)
            System.out.println(inputLine);
    }

    // Terminate all streams
    private static void closeAll(SSLSocket sslSocket, PrintWriter outWriter, BufferedReader inReader) throws IOException
    {
        if(sslSocket != null) sslSocket.close();
        if(outWriter != null) outWriter.close();
        if(inReader != null) inReader.close();
    }

    // Create an SSLSocketFactory based on the certificate if it is available, otherwise use the JVM default certs
    public static SSLSocketFactory getSSLSocketFactory(String certFile)
        throws CertificateException, KeyStoreException, IOException, NoSuchAlgorithmException, KeyManagementException
    {
        if (certFile == null) return (SSLSocketFactory) SSLSocketFactory.getDefault();
        Certificate certificate = CertificateFactory.getInstance("X.509").generateCertificate(new FileInputStream(new File(certFile)));

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

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

        SSLContext sslContext = SSLContext.getInstance("TLS");
        sslContext.init(null, trustManagerFactory.getTrustManagers(), null);

        return sslContext.getSocketFactory();
    }
}

我找到了一个证书提供者，该提供者不属于JDK 8u74的默认JVM受信任主机。提供者是www.identrust.com，但这不是我试图连接的域。该域已从该提供者获得其证书。请参见交叉根覆盖信任JDK/JRE中的默认列表?——读几个条目。另请参阅哪些浏览器和操作系统支持Let 's Encrypt。

因此，为了连接到我感兴趣的域名，它有一个由identrust.com颁发的证书，我执行了以下步骤。基本上，我必须获得identrust.com (DST根CA X3)证书才能被JVM信任。我可以使用Apache HttpComponents 4.5这样做:

1:从证书链下载说明中的indettrust获取证书。单击DST根CA X3链接。

2:保存到“DST Root CA X3.pem”文件中。确保在文件的开头和结尾添加行“-----BEGIN CERTIFICATE-----”和“-----END CERTIFICATE-----”。

3:创建java的keystore文件cacerts。JKS，命令如下:

keytool -import -v -trustcacerts -alias IdenTrust -keypass yourpassword -file dst_root_ca_x3.pem -keystore cacerts.jks -storepass yourpassword

4:复制生成的cacerts。将JKS密钥存储库保存到java/(maven)应用程序的资源目录中。

5:使用以下代码加载该文件，并将其附加到Apache 4.5 HttpClient。这将解决所有拥有indetrust.com颁发的证书的域的问题，util oracle将证书包含到JRE默认的密钥存储库中。

SSLContext sslcontext = SSLContexts.custom()
        .loadTrustMaterial(new File(CalRestClient.class.getResource("/cacerts.jks").getFile()), "yourpasword".toCharArray(),
                new TrustSelfSignedStrategy())
        .build();
// Allow TLSv1 protocol only
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
        sslcontext,
        new String[] { "TLSv1" },
        null,
        SSLConnectionSocketFactory.getDefaultHostnameVerifier());
CloseableHttpClient httpclient = HttpClients.custom()
        .setSSLSocketFactory(sslsf)
        .build();

当项目构建时，cacerts。JKS将被复制到类路径中并从那里加载。我没有，在这个时间点上，测试其他ssl站点，但如果上面的代码“链”在这个证书，那么他们也会工作，但是，我不知道。

参考:自定义SSL上下文和如何使用Java HttpsURLConnection接受自签名证书?

信任所有SSL证书:— 如果希望在测试服务器上进行测试，可以绕过SSL。 但是不要将此代码用于生产。

public static class NukeSSLCerts {
protected static final String TAG = "NukeSSLCerts";

public static void nuke() {
    try {
        TrustManager[] trustAllCerts = new TrustManager[] { 
            new X509TrustManager() {
                public X509Certificate[] getAcceptedIssuers() {
                    X509Certificate[] myTrustedAnchors = new X509Certificate[0];  
                    return myTrustedAnchors;
                }

                @Override
                public void checkClientTrusted(X509Certificate[] certs, String authType) {}

                @Override
                public void checkServerTrusted(X509Certificate[] certs, String authType) {}
            }
        };

        SSLContext sc = SSLContext.getInstance("SSL");
        sc.init(null, trustAllCerts, new SecureRandom());
        HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
        HttpsURLConnection.setDefaultHostnameVerifier(new HostnameVerifier() {
            @Override
            public boolean verify(String arg0, SSLSession arg1) {
                return true;
            }
        });
    } catch (Exception e) { 
    }
}

}

请在Activity或应用程序类的onCreate()函数中调用此函数。

NukeSSLCerts.nuke();

这可以用于Android的Volley。

而不是设置默认的套接字工厂(这在我看来是一件坏事)- yhis只会影响当前连接，而不是你试图打开的每一个SSL连接:

URLConnection connection = url.openConnection();
    // JMD - this is a better way to do it that doesn't override the default SSL factory.
    if (connection instanceof HttpsURLConnection)
    {
        HttpsURLConnection conHttps = (HttpsURLConnection) connection;
        // Set up a Trust all manager
        TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager()
        {

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

            public void checkClientTrusted(
                java.security.cert.X509Certificate[] certs, String authType)
            {
            }

            public void checkServerTrusted(
                java.security.cert.X509Certificate[] certs, String authType)
            {
            }
        } };

        // Get a new SSL context
        SSLContext sc = SSLContext.getInstance("TLSv1.2");
        sc.init(null, trustAllCerts, new java.security.SecureRandom());
        // Set our connection to use this SSL context, with the "Trust all" manager in place.
        conHttps.setSSLSocketFactory(sc.getSocketFactory());
        // Also force it to trust all hosts
        HostnameVerifier allHostsValid = new HostnameVerifier() {
            public boolean verify(String hostname, SSLSession session) {
                return true;
            }
        };
        // and set the hostname verifier.
        conHttps.setHostnameVerifier(allHostsValid);
    }
InputStream stream = connection.getInputStream();

您可以通过在RestTemplate级别禁用它来实现这一点。 注意，此TrustStrategy将信任所有证书，并且使用NoopHostnameVerifier()禁用了主机名验证。

public RestTemplate getRestTemplate() throws KeyStoreException, NoSuchAlgorithmException, KeyManagementException {
    TrustStrategy acceptingTrustStrategy = (x509Certificates, s) -> true;
    SSLContext sslContext = org.apache.http.ssl.SSLContexts.custom().loadTrustMaterial(null, acceptingTrustStrategy).build();
    SSLConnectionSocketFactory csf = new SSLConnectionSocketFactory(sslContext, new NoopHostnameVerifier());
    CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(csf).build();
    HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
    requestFactory.setHttpClient(httpClient);
    return new RestTemplate(requestFactory);
}       

这是第一个有太多答案的古老问题，我认为我可以提供一个更有用的想法:如果服务器所有者拒绝以可信任的方式离线向我提供他们的证书，我会使用这个选项:

从服务器本身检索证书(使用命令行工具而不是浏览器) 将该证书添加到java密钥存储库以信任它。将显示证书的详细信息，以验证它。

# HOSTNAME_PORT is the host that you want to connect to - example: HOSTNAME_PORT=stackoverflow.com:443
HOSTNAME_PORT=hostname_part_of_url_without_https:port

# whatever you want to call the key within the Java key store
MY_KEY_ALIAS=the_key_I_added_with_help_from_stackoverflow

openssl s_client -showcerts -connect $HOSTNAME_PORT </dev/null 2>/dev/null|openssl x509 -outform PEM >mycertfile.pem
sudo keytool -trustcacerts -keystore $JAVA_HOME/jre/lib/security/cacerts/pki/java/cacerts -storepass changeit -importcert -alias $MY_KEY_ALIAS -file mycertfile.pem 

在出现提示时输入yes，但只有在您真正信任显示给您的证书并希望将其添加到计算机的全局java密钥存储库时才可以这样做。

通知你:$ JAVA_HOME / jre / lib /安全/除 在我的情况下(CentOS 7)指向: /etc/pki/java/cacerts