最近有客户反馈java调用报错Received fatal alert: protocol_version，直接联想到是最近调整的WAF的TLS配置，取消了TLS 1.0所致。

取消TLS1.0主要是以下原因：

TLS 1.0 于 2021 年 3 月正式弃用。 此外，TLS 1.0 在用于保护传入或传出网站的敏感信息时，不被视为 PCI 数据安全标准 3.2（.1） 所定义和要求的”强加密”。 根据PCI的说法，“2018年6月30日是禁用SSL /早期TLS和实施更安全的加密协议的最后期限 - TLS 1.1或更高版本（强烈建议TLS v1.2），以满足PCI数据安全标准（PCI DSS）保护支付数据。

问题分析

大部分客户没问题，但部分客户有问题，结合以往经验，很快得知跟客户的代码环境有关。经查阅资料可知：JDK8默认使用的是TLS v1.2；而JDK7和JDK6默认使用的是TLS v1.0，需要代码进行特别指定版本号。以下是各JDK版本对TLS协议的支持对比信息：

获得域名网站所支持的ssl协议方法：

https://tech.hiofd.com/p/get-domain-ssl-protocols/

—

解决方案

解决方案1

没什么特殊情况下，解决Received fatal alert: protocol_version问题，直接升级到JDK8即可解决。

解决方案2

修改JDK默认协议，参考以下代码：

使用HttpClient的：

private static CloseableHttpClient getHttpclient(){
	SSLContext context = SSLContext.getInstance("TLSv1.2");
	context.init(null, null, null);
	SSLContext.setDefault(context);
	...
}

使用RestTemplate的：

import org.springframework.http.client.SimpleClientHttpRequestFactory;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.InetAddress;
import java.net.Socket;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;


public class HttpsClientRequestFactory extends SimpleClientHttpRequestFactory {

    @Override
    protected void prepareConnection(HttpURLConnection connection, String httpMethod) {
        try {
            if (!(connection instanceof HttpsURLConnection)) {
                throw new RuntimeException("An instance of HttpsURLConnection is expected");
            }

            HttpsURLConnection httpsConnection = (HttpsURLConnection) connection;

            TrustManager[] trustAllCerts = new TrustManager[]{new X509TrustManager() {
                @Override
                public java.security.cert.X509Certificate[] getAcceptedIssuers() {
                    return null;
                }

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

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

            }
            };
            // 强制使用 TLSv1.2 解决 Received fatal alert: protocol_version; nested exception is javax.net.ssl.SSLException: Received fatal alert: protocol_version 异常情况
            SSLContext sslContext = SSLContext.getInstance("TLSv1.2");
            sslContext.init(null, trustAllCerts, new SecureRandom());
            httpsConnection.setSSLSocketFactory(new MyCustomSSLSocketFactory(sslContext.getSocketFactory()));

            httpsConnection.setHostnameVerifier(new HostnameVerifier() {
                @Override
                public boolean verify(String s, SSLSession sslSession) {
                    return true;
                }
            });

            super.prepareConnection(httpsConnection, httpMethod);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * SSLSocketFactory用于创建 SSLSockets
     */
    private class MyCustomSSLSocketFactory extends SSLSocketFactory {

        private final SSLSocketFactory delegate;

        public MyCustomSSLSocketFactory(SSLSocketFactory delegate) {
            this.delegate = delegate;
        }

        // 返回默认启用的密码套件。除非一个列表启用，对SSL连接的握手会使用这些密码套件。
        // 这些默认的服务的最低质量要求保密保护和服务器身份验证
        @Override
        public String[] getDefaultCipherSuites() {
            return delegate.getDefaultCipherSuites();
        }

        // 返回的密码套件可用于SSL连接启用的名字
        @Override
        public String[] getSupportedCipherSuites() {
            return delegate.getSupportedCipherSuites();
        }


        @Override
        public Socket createSocket(final Socket socket, final String host, final int port, final boolean autoClose) throws IOException {
            final Socket underlyingSocket = delegate.createSocket(socket, host, port, autoClose);
            return overrideProtocol(underlyingSocket);
        }


        @Override
        public Socket createSocket(final String host, final int port) throws IOException {
            final Socket underlyingSocket = delegate.createSocket(host, port);
            return overrideProtocol(underlyingSocket);
        }

        @Override
        public Socket createSocket(final String host, final int port, final InetAddress localAddress, final int localPort) throws IOException {
            final Socket underlyingSocket = delegate.createSocket(host, port, localAddress, localPort);
            return overrideProtocol(underlyingSocket);
        }

        @Override
        public Socket createSocket(final InetAddress host, final int port) throws IOException {
            final Socket underlyingSocket = delegate.createSocket(host, port);
            return overrideProtocol(underlyingSocket);
        }

        @Override
        public Socket createSocket(final InetAddress host, final int port, final InetAddress localAddress, final int localPort) throws IOException {
            final Socket underlyingSocket = delegate.createSocket(host, port, localAddress, localPort);
            return overrideProtocol(underlyingSocket);
        }

        private Socket overrideProtocol(final Socket socket) {
            if (!(socket instanceof SSLSocket)) {
                throw new RuntimeException("An instance of SSLSocket is expected");
            }
            // 兼容支持协议版本
            ((SSLSocket) socket).setEnabledProtocols(new String[]{"TLSv1", "TLSv1.1", "TLSv1.2"});
            return socket;
        }
    }
}