javaEmail二：导入SSL证书文件

• 代码样例

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.security.KeyStore;
import java.security.MessageDigest;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

/**
 * 下载证书功能
 */
public class InstallCert {

    private static final String CERT_FILE = "smtp.server.cert";
    private static final char[] HEXDIGITS = "0123456789abcdef".toCharArray();

    public static void main(String[] args) throws Exception {

        String host; // 服务器地址
        int port; // 服务器端口, 默认443
        char[] passphrase;

        if ((args.length == 1) || (args.length == 2)) {
            String[] c = args[0].split(":");
            host = c[0];
            port = (c.length == 1) ? 443 : Integer.parseInt(c[1]);
            String p = (args.length == 1) ? "changeit" : args[1];
            passphrase = p.toCharArray();
        } else {
            System.out.println("Usage: java InstallCert [:port] [passphrase]");
            return;
        }

        File file = new File(CERT_FILE);
        if (file.isFile() == false) {
            char SEP = File.separatorChar;
            File dir = new File(System.getProperty("java.home")
                    + SEP + "lib" + SEP + "security");
            file = new File(dir, CERT_FILE);
            if (file.isFile() == false) {
                file = new File(dir, "cacerts");
            }
        }
        System.out.println("Loading KeyStore " + file + "...");
        InputStream in = new FileInputStream(file);
        KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
        ks.load(in, passphrase);
        in.close();

        SSLContext context = SSLContext.getInstance("TLS");
        TrustManagerFactory tmf =         TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        tmf.init(ks);
        X509TrustManager defaultTrustManager =
                (X509TrustManager) tmf.getTrustManagers()[0];
        SavingTrustManager tm = new SavingTrustManager(defaultTrustManager);
        context.init(null, new TrustManager[]{tm}, null);
        SSLSocketFactory factory = context.getSocketFactory();

        System.out.println("Opening connection to " + host + ":" + port + "...");
        SSLSocket socket = (SSLSocket) factory.createSocket(host, port);
        socket.setSoTimeout(10000);
        try {
            System.out.println("Starting SSL handshake...");
            socket.startHandshake();
            socket.close();
            System.out.println("No errors, certificate is already trusted");
        } catch (SSLException e) {
            System.out.println("Certificate has not been trusted");
        }

        X509Certificate[] chain = tm.chain;
        if (chain == null) {
            System.out.println("Could not obtain server certificate chain");
            return;
        }

        BufferedReader reader =
                new BufferedReader(new InputStreamReader(System.in));

        System.out.println();
        System.out.println("Server sent " + chain.length + " certificate(s):");
        System.out.println();
        MessageDigest sha1 = MessageDigest.getInstance("SHA1");
        MessageDigest md5 = MessageDigest.getInstance("MD5");
        for (int i = 0; i < chain.length; i++) {
            X509Certificate cert = chain[i];
            System.out.println(" " + (i + 1) + " Subject " + cert.getSubjectDN());
            System.out.println("   Issuer  " + cert.getIssuerDN());
            sha1.update(cert.getEncoded());
            System.out.println("   sha1    " + toHexString(sha1.digest()));
            md5.update(cert.getEncoded());
            System.out.println("   md5     " + toHexString(md5.digest()));
            System.out.println();
        }

        System.out.println("Enter certificate to add to trusted keystore or 'q' to quit: [1]");
        String line = reader.readLine().trim();
        int k;
        try {
            k = (line.length() == 0) ? 0 : Integer.parseInt(line) - 1;
        } catch (NumberFormatException e) {
            System.out.println("KeyStore not changed");
            return;
        }

        X509Certificate cert = chain[k];
        String alias = host + "-" + (k + 1);
        ks.setCertificateEntry(alias, cert);

        OutputStream out = new FileOutputStream("jssecacerts");
        ks.store(out, passphrase);
        out.close();

        System.out.println();
        System.out.println(cert);
        System.out.println();
        System.out.println("Added certificate to keystore 'jssecacerts' using alias '" + alias + "'");
    }

    private static String toHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder(bytes.length * 3);
        for (int b : bytes) {
            b &= 0xff;
            sb.append(HEXDIGITS[b >> 4]);
            sb.append(HEXDIGITS[b & 15]);
            sb.append(' ');
        }
        return sb.toString();
    }

    private static class SavingTrustManager implements X509TrustManager {

        private final X509TrustManager tm;
        private X509Certificate[] chain;

        SavingTrustManager(X509TrustManager tm) {
            this.tm = tm;
        }

        @Override
        public X509Certificate[] getAcceptedIssuers() {
            throw new UnsupportedOperationException();
        }

        @Override
        public void checkClientTrusted(X509Certificate[] chain, String authType)
                throws CertificateException {
            throw new UnsupportedOperationException();
        }

        @Override
        public void checkServerTrusted(X509Certificate[] chain, String authType)
                throws CertificateException {
            this.chain = chain;
            tm.checkServerTrusted(chain, authType);
        }
    }
}

1. 执行证书类

java package com.vipshop.passport.mail.InstallCert smtp.server.com:465

2. 下载证书过程

Loading KeyStore D:\Program Files (x86)\Java\jre\lib\security\cacerts...
Starting SSL handshake...
Certificate has not been trusted

Server sent 1 certificate(s):
1 Subject CN=demo.coremail.cn, OU=Coremail, O=Mailtech, L=GuangZhou, ST=GuangDong, C=CN
   Issuer  CN=ca.mailtech.cn, OU=CA, O=Mailtech, L=GuangZhou, ST=GuangDong, C=CN
   sha1    32 ac 92 0f 95 44 90 b8 26 05 b2 fc 9a 91 38 ff ba 33 18 e2
   md5     83 59 8d fd 1a fe dc 57 ff 5c 7a ba c9 50 68 b0

Enter certificate to add to trusted keystore or 'q' to quit: [1]

3. 输入数字1并回车，程序会将证书下载到当前文件夹中的smtp.server.cert，将这个文件放到$JAVA_HOME/jre/lib/security文件夹中。

• 本文参考文档
  https://www.iteye.com/blog/hoochiang-1938338