使用Java自带的mail API实现邮件发送功能全过程

　　/*

　　* Copyright 2006 Sun Microsystems, Inc. All Rights Reserved.

　　*

　　* Redistribution and use in source and binary forms, with or without

　　* modification, are permitted provided that the following conditions

　　* are met:

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　　* - Redistributions of source code must retain the above copyright

　　* notice, this list of conditions and the following disclaimer.

　　*

　　* - Redistributions in binary form must reproduce the above copyright

　　* notice, this list of conditions and the following disclaimer in the

　　* documentation and/or other materials provided with the distribution.

　　*

　　* - Neither the name of Sun Microsystems nor the names of its

　　* contributors may be used to endorse or promote products derived

　　* from this software without specific prior written permission.

　　*

　　* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

　　* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

　　* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

　　* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR

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　　import java.io.*;

　　import java.net.URL;

　　import java.security.*;

　　import java.security.cert.*;

　　import javax.net.ssl.*;

　　public class InstallCert {

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

　　String host;

　　int port;

　　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("jssecacerts");

　　if (file.isFile() == false) {

　　char SEP = File.separatorChar;

　　File dir = new File(System.getProperty("java.home") + SEP

　　+ "lib" + SEP + "security");

　　file = new File(dir, "jssecacerts");

　　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();

　　System.out.println("No errors, certificate is already trusted");

　　} catch (SSLException e) {

　　System.out.println();

　　e.printStackTrace(System.out);

　　}

　　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 final char[] HEXDIGITS = "0123456789abcdef".toCharArray();

　　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;

　　}

　　public X509Certificate[] getAcceptedIssuers() {

　　throw new UnsupportedOperationException();

　　}

　　public void checkClientTrusted(X509Certificate[] chain, String authType)

　　throws CertificateException {

　　throw new UnsupportedOperationException();

　　}

　　public void checkServerTrusted(X509Certificate[] chain, String authType)

　　throws CertificateException {

　　this.chain = chain;

　　tm.checkServerTrusted(chain, authType);

　　}

　　}

　　}