获取服务端https证书 - Java版

package org.test;

import java.net.URL;
import java.security.MessageDigest;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import javax.net.ssl.HttpsURLConnection;

public class Application {
public static void main(String[] args) throws Exception {
URL url = new URL("https://www.sina.com.cn");
HttpsURLConnection conn = (HttpsURLConnection)url.openConnection();
conn.connect();
Certificate[] certs = conn.getServerCertificates();    //会拿到完整的证书链
X509Certificate cert = (X509Certificate)certs[0];    //cert[0]是证书链的最下层
System.out.println("序号：" + cert.getSerialNumber());
System.out.println("颁发给：" + cert.getSubjectDN().getName());
System.out.println("颁发者：" + cert.getIssuerDN().getName());
System.out.println("起始：" + cert.getNotBefore());
System.out.println("过期：" + cert.getNotAfter());
System.out.println("算法：" + cert.getSigAlgName());
System.out.println("指纹：" + getThumbPrint(cert));
conn.disconnect();
}

private static String getThumbPrint(X509Certificate cert) throws Exception {
MessageDigest md = MessageDigest.getInstance("SHA-1");
byte[] der = cert.getEncoded();
md.update(der);
byte[] digest = md.digest();
return bytesToHexString(digest);
}

private static String bytesToHexString(byte[] src) {
StringBuilder stringBuilder = new StringBuilder("");
if (src == null || src.length <= 0) {
return null;
}
for (int i = 0; i < src.length; i++) {
int v = src[i] & 0xFF;
String hv = Integer.toHexString(v);
if (hv.length() < 2) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
}
return stringBuilder.toString();
}
}