e224. exporting a certificate to a file.txt

这里面包含了一百多个JAVA源文件

See also e225 Importing a Certificate from a File. 
    // This method writes a certificate to a file. If binary is false, the
    // certificate is base64 encoded.
    public static void export(java.security.cert.Certificate cert, File file, boolean binary) {
        try {
            // Get the encoded form which is suitable for exporting
            byte[] buf = cert.getEncoded();
    
            FileOutputStream os = new FileOutputStream(file);
            if (binary) {
                // Write in binary form
                os.write(buf);
            } else {
                // Write in text form
                Writer wr = new OutputStreamWriter(os, Charset.forName("UTF-8"));
                wr.write("-----BEGIN CERTIFICATE-----\n");
                wr.write(new sun.misc.BASE64Encoder().encode(buf));
                wr.write("\n-----END CERTIFICATE-----\n");
                wr.flush();
            }
            os.close();
        } catch (CertificateEncodingException e) {
        } catch (IOException e) {
        }
    }

If the certificate is in the key store, it can exported using keytool: 
    // Export in binary
    > keytool -storepass my-keystore-password -alias myalias -export -file outfilename.cer
    
    // Export in text format
    > keytool -storepass my-keystore-password -alias myalias -export -rfc -file outfilename.cer


Here's an example of the text form of an exported certificate: 
    -----BEGIN CERTIFICATE-----
    MIIC6TCCAqcCBDxgu/IwCwYHKoZIzjgEAwUAMFoxCzAJBgNVBAYTAlVTMQswCQYDVQQIEwJDQTES
    MBAGA1UEBxMJUGFsbyBBbHRvMQowCAYDVQQKEwFJMQswCQYDVQQLEwJNZTERMA8GA1UEAxMIUGF0
    IENoYW4wHhcNMDIwMjA2MDUxNTMwWhcNMDIwNTA3MDUxNTMwWjBaMQswCQYDVQQGEwJVUzELMAkG
    A1UECBMCQ0ExEjAQBgNVBAcTCVBhbG8gQWx0bzEKMAgGA1UEChMBSTELMAkGA1UECxMCTWUxETAP
    BgNVBAMTCFBhdCBDaGFuMIIBuDCCASwGByqGSM44BAEwggEfAoGBAP1/U4EddRIpUt9KnC7s5Of2
    EbdSPO9EAMMeP4C2USZpRV1AIlH7WT2NWPq/xfW6MPbLm1Vs14E7gB00b/JmYLdrmVClpJ+f6AR7
    ECLCT7up1/63xhv4O1fnxqimFQ8E+4P208UewwI1VBNaFpEy9nXzrith1yrv8iIDGZ3RSAHHAhUA
    l2BQjxUjC8yykrmCouuEC/BYHPUCgYEA9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdR
    WVeOutRZT+ZxBxCBgLRJFnEj6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx
    +2J6ASQ7zKTxvqhRkImog9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSoDgYUAAoGBAPyx9uQ1PKBYO/2G
    RPzbW4y6pphNRmObJQWbjY/ERuCQwLRrpREh9sgMnptZjRzLVpWdzxNa9bFMFXAYMgoTUIgAZ9yN
    WPjp/JiFfzdIq3CY0CEey42M3mbD3pWsF9x4SSsJTpDobX/pm5XgtkhZXBZYtBk813Xv2LxyZ3OI
    W1JnMAsGByqGSM44BAMFAAMvADAsAhQ5wayd5cpEo/vHmF7G5gVQ9cMKKAIUMfk2ZYxNdhe6oNmH
    nR0AhnEHILE=
    -----END CERTIFICATE-----

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