使用Java代码实现采用HTTPS和TLS 1.2版本建立连接，并完成双向TLS认证 (mTLS)的示例

以下是使用Java代码实现采用HTTPS和TLS 1.2版本建立连接，并完成双向TLS认证（mTLS）的示例：

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.security.KeyStore;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLException;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

public class SSLExample {
    public static void main(String[] args) throws Exception {
        // Load client certificate and private key for mTLS
        String keyStorePath = "client.jks";
        String keyStorePassword = "password";
        String keyPassword = "password";

        KeyStore keyStore = KeyStore.getInstance("JKS");
        keyStore.load(SSLExample.class.getClassLoader().getResourceAsStream(keyStorePath),
                keyStorePassword.toCharArray());

        KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
        keyManagerFactory.init(keyStore, keyPassword.toCharArray());

        // Load server truststore for server certificate verification
        String trustStorePath = "server.jks";
        String trustStorePassword = "password";

        KeyStore trustStore = KeyStore.getInstance("JKS");
        trustStore.load(SSLExample.class.getClassLoader().getResourceAsStream(trustStorePath),
                trustStorePassword.toCharArray());

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

        // Create SSL context with TLS 1.2 protocol and mTLS configuration
        SSLContext sslContext = SSLContext.getInstance("TLSv1.2");
        sslContext.init(keyManagerFactory.getKeyManagers(), trustManagerFactory.getTrustManagers(), null);

        // Set default SSL context for HTTPS connection
        HttpsURLConnection.setDefaultSSLSocketFactory(sslContext.getSocketFactory());

        // Create URL object for HTTPS endpoint
        URL url = new URL("https://example.com/api");

        // Open HTTPS connection
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();

        // Set request method and headers
        connection.setRequestMethod("GET");
        connection.setRequestProperty("User-Agent", "Mozilla/5.0");

        // Get response from HTTPS endpoint
        try (InputStream inputStream = connection.getInputStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (SSLException e) {
            e.printStackTrace();
        } finally {
            connection.disconnect();
        }
    }

    // Trust manager to accept all server certificates
    private static final TrustManager[] TRUST_ALL_CERTIFICATES = new TrustManager[] { new X509TrustManager() {
        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
            // Do nothing
        }

        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
            // Do nothing
        }

        public X509Certificate[] getAcceptedIssuers() {
            return new X509Certificate[0];
        }
    } };
}

在上面的示例中，我们使用了Java的`HttpsURLConnection`类来建立连接。我们首先加载客户端证书和私钥，并使用它们来创建`KeyManager`对象。然后，我们加载服务器信任库并使用它来创建`TrustManager`对象。接下来，我们使用这些`KeyManager`和`TrustManager`对象创建一个SSL上下文对象，该对象使用TLS 1.2协议并完成mTLS配置。最后，我们将默认的SSL上下文设置为HTTPS连接，并打开连接以向服务器发送请求。

在此示例中，我们还提供了一个`TrustManager`实现，它接受所有服务器证书。这不是一个好的做法，因为它会使您的应用程序容易受到中间人攻击。在实际生产环境中，您应该使用一个更安全的`TrustManager`实现，它会验证服务器证书并拒绝不受信任的证书。