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

有一个更好的替代信任所有证书的方法:创建一个TrustStore，它专门信任给定的证书，并使用它来创建一个SSLContext，从中获取SSLSocketFactory在HttpsURLConnection上进行设置。以下是完整的代码:

File crtFile = new File("server.crt");
Certificate certificate = CertificateFactory.getInstance("X.509").generateCertificate(new FileInputStream(crtFile));
// Or if the crt-file is packaged into a jar file:
// CertificateFactory.getInstance("X.509").generateCertificate(this.class.getClassLoader().getResourceAsStream("server.crt"));


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);

HttpsURLConnection connection = (HttpsURLConnection) new URL(url).openConnection();
connection.setSSLSocketFactory(sslContext.getSocketFactory());

您也可以直接从文件加载KeyStore，或者从任何受信任的来源检索X.509证书。

注意，对于这段代码，将不使用cacerts中的证书。这个特定的HttpsURLConnection将只信任这个特定的证书。

接受的答案很好，但我想添加一些东西，因为我在Mac上使用IntelliJ，无法使用JAVA_HOME路径变量让它工作。

事实证明，从IntelliJ运行应用程序时，Java Home是不同的。

要找出它的确切位置，只需执行System.getProperty("java.home")，因为可信证书就是从那里读取的。

Apache HttpClient 4.5支持接受自签名证书:

SSLContext sslContext = SSLContexts.custom()
    .loadTrustMaterial(new TrustSelfSignedStrategy())
    .build();
SSLConnectionSocketFactory socketFactory =
    new SSLConnectionSocketFactory(sslContext);
Registry<ConnectionSocketFactory> reg =
    RegistryBuilder.<ConnectionSocketFactory>create()
    .register("https", socketFactory)
    .build();
HttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(reg);        
CloseableHttpClient httpClient = HttpClients.custom()
    .setConnectionManager(cm)
    .build();
HttpGet httpGet = new HttpGet(url);
CloseableHttpResponse sslResponse = httpClient.execute(httpGet);

这将构建一个SSL套接字工厂，它将使用TrustSelfSignedStrategy，将其注册到自定义连接管理器，然后使用该连接管理器执行HTTP GET。

我同意那些高呼“不要在生产环境中这样做”的人，但是在生产环境之外接受自签名证书是有用例的;我们在自动化集成测试中使用它们，因此即使不在生产硬件上运行，我们也在使用SSL(就像在生产中一样)。

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();