java 数字证书信息的获取实例-java学习笔记(2)

public static X509Certificate getCert(String fileName) throws Exception {//从一个有效的证书文件来创建证书..
InputStream inStream = new FileInputStream(fileName);
CertificateFactory cf = CertificateFactory.getInstance("X.509");//用证书工厂来创建证书..
X509Certificate cert = (X509Certificate)cf.generateCertificate(inStream);
inStream.close();
return cert;
}
public static void showCert( X509Certificate cert ) {//输出证书的各项信息..
System.out.println("Version: " + cert.getVersion());//证书版本..
System.out.println("SerialNumber: " + cert.getSerialNumber().toString(16) );//证书序列号..
System.out.println("SignatureAlgorithm: " + cert.getSigAlgName());//证书签名算法..
X500Principal principal = cert.getIssuerX500Principal();
System.out.println("IssuerName: /n" + principal.getName(X500Principal.RFC1779));//证书颁发者
//System.out.println(principal.hashCode());
GregorianCalendar gcal = new GregorianCalendar();
System.out.print("ValidityFrom: ");
gcal.setTime(cert.getNotBefore());//证书有效期从..
System.out.println(gcal.get(GregorianCalendar.YEAR)+"/"+gcal.get(GregorianCalendar.MONTH)+"/"+gcal.get(GregorianCalendar.DAY_OF_MONTH)+"  "+gcal.get(GregorianCalendar.HOUR_OF_DAY)+":"+gcal.get(GregorianCalendar.MINUTE)+":"+gcal.get(GregorianCalendar.SECOND));
System.out.print("ValidityTo: ");
gcal.setTime(cert.getNotAfter());//证书有效期到..
System.out.println(gcal.get(GregorianCalendar.YEAR)+"/"+gcal.get(GregorianCalendar.MONTH)+"/"+gcal.get(GregorianCalendar.DAY_OF_MONTH)+"  "+gcal.get(GregorianCalendar.HOUR_OF_DAY)+":"+gcal.get(GregorianCalendar.MINUTE)+":"+gcal.get(GregorianCalendar.SECOND));
principal = cert.getSubjectX500Principal();
System.out.println("SubjectName: /n" + principal.getName(X500Principal.RFC1779));//证书使用者
PublicKey pkey = cert.getPublicKey();//获得公钥
System.out.println("PublicKeyAlgorithm: " + pkey.getAlgorithm() );//公钥算法
System.out.println("PublicKeyCode: " + pkey.getFormat());//公钥格式
byte[] pkeycode = pkey.getEncoded();//公钥的标准编码形式..
//System.out.println(pkeycode.length);
/*
* Maybe the First 22 bytes are Algorithm info..
* The rest 160 - 22 = 138 bytes are as same as those in Win7 Cert View..
*/
for ( int i = 22; i < pkeycode.length; i++ ) {
System.out.print(Integer.toHexString( pkeycode[i] & 0XFF));
System.out.print(" ");
}
System.out.println("");
GregorianCalendar exdate = new GregorianCalendar();;
System.out.println(exdate.get(GregorianCalendar.YEAR));
Date date = (exdate.getTime());
try {//检测证书是否有效
cert.checkValidity(date);
}
catch ( CertificateExpiredException e ){//证书已经过期
System.out.println("Expired");
System.out.println(e.getMessage());
}
catch ( CertificateNotYetValidException e ) {//证书还未生效
System.out.println("Too early");
System.out.println(e.getMessage());
}
}