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

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.

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;
        }
    }
}

有这样的问题。

Tried a few solutions. But found that even if it's same project, when it's on other one's working place, it's totally fine. No extra settings needed. So we guessed it's an enviroment issue. We tried changing JDK version, IDE but didn't work. it took about 4 hours for investigation, until we tried the top-rated answer. I didn't find the error mentioned in that answer but I found via my browser about HTTP URL (lock) that there was a certification of Charles. Then I realized my charles was on all the time. As long as I turned that off, it's working all fine.

所以我留下了我的经验可能对你的案子有帮助。

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

我有同样的问题与证书错误，这是因为SNI:我使用的http客户端没有SNI实现。所以版本更新起了作用

   <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.3.6</version>
    </dependency>