以下是我在macOS上可靠工作的方法。请确保将example.com和443替换为您试图连接的实际主机名和端口，并提供一个自定义别名。第一个命令从远程服务器下载提供的证书，并以x509格式保存在本地。第二个命令将保存的证书加载到Java的SSL信任存储区。

openssl x509 -in <(openssl s_client -connect example.com:443 -prexit 2>/dev/null) -out ~/example.crt
sudo keytool -importcert -file ~/example.crt -alias example -keystore $(/usr/libexec/java_home)/jre/lib/security/cacerts -storepass changeit

@Gabe martin - dempasy的回答对我很有帮助。我写了一个相关的小脚本。使用方法非常简单。

从主机安装证书:

> sudo ./java-cert-importer.sh example.com

删除已经安装的证书。

> sudo ./java-cert-importer.sh example.com --delete

java-cert-importer.sh

#!/usr/bin/env bash

# Exit on error
set -e

# Ensure script is running as root
if [ "$EUID" -ne 0 ]
  then echo "WARN: Please run as root (sudo)"
  exit 1
fi

# Check required commands
command -v openssl >/dev/null 2>&1 || { echo "Required command 'openssl' not installed. Aborting." >&2; exit 1; }
command -v keytool >/dev/null 2>&1 || { echo "Required command 'keytool' not installed. Aborting." >&2; exit 1; }

# Get command line args
host=$1; port=${2:-443}; deleteCmd=${3:-${2}}

# Check host argument
if [ ! ${host} ]; then
cat << EOF
Please enter required parameter(s)

usage:  ./java-cert-importer.sh <host> [ <port> | default=443 ] [ -d | --delete ]

EOF
exit 1
fi;

if [ "$JAVA_HOME" ]; then
    javahome=${JAVA_HOME}
elif [[ "$OSTYPE" == "linux-gnu" ]]; then # Linux
    javahome=$(readlink -f $(which java) | sed "s:bin/java::")
elif [[ "$OSTYPE" == "darwin"* ]]; then # Mac OS X
    javahome="$(/usr/libexec/java_home)/jre"
fi

if [ ! "$javahome" ]; then
    echo "WARN: Java home cannot be found."
    exit 1
elif [ ! -d "$javahome" ]; then
    echo "WARN: Detected Java home does not exists: $javahome"
    exit 1
fi

echo "Detected Java Home: $javahome"

# Set cacerts file path
cacertspath=${javahome}/lib/security/cacerts
cacertsbackup="${cacertspath}.$$.backup"

if ( [ "$deleteCmd" == "-d" ] || [ "$deleteCmd" == "--delete" ] ); then
    sudo keytool -delete -alias ${host} -keystore ${cacertspath} -storepass changeit
    echo "Certificate is deleted for ${host}"
    exit 0
fi

# Get host info from user
#read -p "Enter server host (E.g. example.com) : " host
#read -p "Enter server port (Default 443) : " port

# create temp file
tmpfile="/tmp/${host}.$$.crt"

# Create java cacerts backup file
cp ${cacertspath} ${cacertsbackup}

echo "Java CaCerts Backup: ${cacertsbackup}"

# Get certificate from speficied host
openssl x509 -in <(openssl s_client -connect ${host}:${port} -prexit 2>/dev/null) -out ${tmpfile}

# Import certificate into java cacerts file
sudo keytool -importcert -file ${tmpfile} -alias ${host} -keystore ${cacertspath} -storepass changeit

# Remove temp certificate file
rm ${tmpfile}

# Check certificate alias name (same with host) that imported successfully
result=$(keytool -list -v -keystore ${cacertspath} -storepass changeit | grep "Alias name: ${host}")

# Show results to user
if [ "$result" ]; then
    echo "Success: Certificate is imported to java cacerts for ${host}";
else
    echo "Error: Something went wrong";
fi;

当您的服务器拥有自签名证书时，就会出现问题。要解决这个问题，可以将该证书添加到JVM的受信任证书列表中。

在本文中，作者描述了如何从浏览器获取证书并将其添加到JVM的cacerts文件中。您可以编辑JAVA_HOME/jre/lib/security/cacerts文件，也可以使用-Djavax.net.ssl.trustStore参数运行应用程序。验证您使用的JDK/JRE，因为这通常是混淆的来源。

请参见:SSL证书服务器名称如何解析/我可以使用keytool添加替代名称吗?如果遇到java.security.cert.CertificateException: No name matching localhost found异常。

我能够让它只与代码工作，即不需要使用keytool:

import com.netflix.config.DynamicBooleanProperty;
import com.netflix.config.DynamicIntProperty;
import com.netflix.config.DynamicPropertyFactory;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.ssl.SSLContexts;
import org.apache.http.conn.ssl.TrustStrategy;
import org.apache.http.conn.ssl.X509HostnameVerifier;
import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
import org.apache.http.impl.nio.client.HttpAsyncClients;
import org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager;
import org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor;
import org.apache.http.impl.nio.reactor.IOReactorConfig;
import org.apache.http.nio.conn.NoopIOSessionStrategy;
import org.apache.http.nio.conn.SchemeIOSessionStrategy;
import org.apache.http.nio.conn.ssl.SSLIOSessionStrategy;

import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocket;
import java.io.IOException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

public class Test
{
    private static final DynamicIntProperty MAX_TOTAL_CONNECTIONS = DynamicPropertyFactory.getInstance().getIntProperty("X.total.connections", 40);
    private static final DynamicIntProperty ROUTE_CONNECTIONS = DynamicPropertyFactory.getInstance().getIntProperty("X.total.connections", 40);
    private static final DynamicIntProperty CONNECT_TIMEOUT = DynamicPropertyFactory.getInstance().getIntProperty("X.connect.timeout", 60000);
    private static final DynamicIntProperty SOCKET_TIMEOUT = DynamicPropertyFactory.getInstance().getIntProperty("X.socket.timeout", -1);
    private static final DynamicIntProperty CONNECTION_REQUEST_TIMEOUT = DynamicPropertyFactory.getInstance().getIntProperty("X.connectionrequest.timeout", 60000);
    private static final DynamicBooleanProperty STALE_CONNECTION_CHECK = DynamicPropertyFactory.getInstance().getBooleanProperty("X.checkconnection", true);

    public static void main(String[] args) throws Exception
    {

        SSLContext sslcontext = SSLContexts.custom()
                .useTLS()
                .loadTrustMaterial(null, new TrustStrategy()
                {
                    @Override
                    public boolean isTrusted(X509Certificate[] chain, String authType) throws CertificateException
                    {
                        return true;
                    }
                })
                .build();
        SSLIOSessionStrategy sslSessionStrategy = new SSLIOSessionStrategy(sslcontext, new AllowAll());

        Registry<SchemeIOSessionStrategy> sessionStrategyRegistry = RegistryBuilder.<SchemeIOSessionStrategy>create()
                .register("http", NoopIOSessionStrategy.INSTANCE)
                .register("https", sslSessionStrategy)
                .build();

        DefaultConnectingIOReactor ioReactor = new DefaultConnectingIOReactor(IOReactorConfig.DEFAULT);
        PoolingNHttpClientConnectionManager connectionManager = new PoolingNHttpClientConnectionManager(ioReactor, sessionStrategyRegistry);
        connectionManager.setMaxTotal(MAX_TOTAL_CONNECTIONS.get());
        connectionManager.setDefaultMaxPerRoute(ROUTE_CONNECTIONS.get());

        RequestConfig requestConfig = RequestConfig.custom()
                .setSocketTimeout(SOCKET_TIMEOUT.get())
                .setConnectTimeout(CONNECT_TIMEOUT.get())
                .setConnectionRequestTimeout(CONNECTION_REQUEST_TIMEOUT.get())
                .setStaleConnectionCheckEnabled(STALE_CONNECTION_CHECK.get())
                .build();

        CloseableHttpAsyncClient httpClient = HttpAsyncClients.custom()
                .setSSLStrategy(sslSessionStrategy)
                .setConnectionManager(connectionManager)
                .setDefaultRequestConfig(requestConfig)
                .build();

        httpClient.start();

        // use httpClient...
    }

    private static class AllowAll implements X509HostnameVerifier
    {
        @Override
        public void verify(String s, SSLSocket sslSocket) throws IOException
        {}

        @Override
        public void verify(String s, X509Certificate x509Certificate) throws SSLException {}

        @Override
        public void verify(String s, String[] strings, String[] strings2) throws SSLException
        {}

        @Override
        public boolean verify(String s, SSLSession sslSession)
        {
            return true;
        }
    }
}

这解决了我的问题，

我们需要将证书导入到本地java。如果不是，我们可以得到下面的异常。

    javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
        at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)

SSLPOKE是一个可以从本地计算机测试https连接的工具。

命令测试连通性。

"%JAVA_HOME%/bin/java" SSLPoke <hostname> 443

    sun.security.validator.ValidatorException: PKIX path building failed: 
    sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)
        at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
        at sun.security.validator.Validator.validate(Validator.java:260)
        at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
        at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
        at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1496)
        at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
        at sun.security.ssl.Handshaker.processLoop(Handshaker.java:1026)
        at sun.security.ssl.Handshaker.process_record(Handshaker.java:961)
        at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062)
        at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
        at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:747)
        at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:123)
        at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:138)
        at SSLPoke.main(SSLPoke.java:31)
    Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to 
    requested target
        at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
        at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
        at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382)
        ... 15 more

keytool -import -alias <anyname> -keystore "%JAVA_HOME%/jre/lib/security/cacerts" -file <cert path>

这将首先提示“Enter keystore password:”changeit是默认密码。最后一个提示“信任这个证书?”[no]:"，提供"yes"将证书添加到密钥库。

Verfication:

C:\tools>"%JAVA_HOME%/bin/java" SSLPoke <hostname> 443
Successfully connected    

The source of this error on my Apache 2.4 instance (using a Comodo wildcard certificate) was an incomplete path to the SHA-1 signed root certificate. There were multiple chains in the issued certificate, and the chain leading to a SHA-1 root certificate was missing an intermediate certificate. Modern browsers know how to handle this, but Java 7 doesn't handle it by default (although there are some convoluted ways to accomplish this in code). The result is error messages that look identical to the case of self-signed certificates:

Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:196)
    at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:268)
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
    ... 22 more

In this case, the "unable to find valid certification path to requested target" message is being produced due to the missing intermediate certificate. You can check which certificate is missing using SSL Labs test against the server. Once you find the appropriate certificate, download it and (if the server is under your control) add it to the certificate bundle. Alternatively, you can import the missing certificate locally. Accommodating this issue on the server is a more general solution to the problem.