HttpsURLConnection 扩展 HttpURLConnection，支持各种特定于 https 功能。此类使用 HostnameVerifier 和 SSLSocketFactory。为这两个类都定义了默认实现。但是，可以根据每个类（静态的）或每个实例来替换该实现。所有新 HttpsURLConnection 实例在创建时将被分配“默认的”静态值，通过在连接前调用每个实例适当的 set 方法可以重写这些值

在URL前加https://前缀表明是用SSL加密的。 你的电脑与服务器之间收发的信息传输将更加安全。 

Web服务器启用SSL需要获得一个服务器证书并将该证书与要使用SSL的服务器绑定。 

http和https使用的是完全不同的连接方式,用的端口也不一样,前者是80,后者是443。http的连接很简单,是无状态的,... 

HTTPS协议是由SSL+HTTP协议构建的可进行加密传输、身份认证的网络协议 

要比http协议安全

import java.io.*;import java.net.*;import java.security.*;import java.security.cert.*;import javax.net.ssl.*;public class HttpsURLConnectionTest {    private String url = "https://esales.the9.com/esa/DealerLogin.php?txt_sLogin=andysmile234&pas_sPwd=343211&userstatus=1";    private myX509TrustManager xtm = new myX509TrustManager();    private myHostnameVerifier hnv = new myHostnameVerifier();    public HttpsURLConnectionTest() {        SSLContext sslContext = null;        try {            sslContext = SSLContext.getInstance("TLS"); //或SSL            X509TrustManager[] xtmArray = new X509TrustManager[] {xtm};            sslContext.init(null, xtmArray, new java.security.SecureRandom());        } catch (GeneralSecurityException e) {            e.printStackTrace();        }        if (sslContext != null) {            HttpsURLConnection.setDefaultSSLSocketFactory(sslContext.getSocketFactory());        }        HttpsURLConnection.setDefaultHostnameVerifier(hnv);    }    public void run() {        HttpsURLConnection urlCon = null;        try {            urlCon = (HttpsURLConnection)(new URL(url)).openConnection();            urlCon.setDoOutput(true);            urlCon.setRequestMethod("POST");            urlCon.setRequestProperty("Content-Length", "1024");            urlCon.setUseCaches(false);            urlCon.setDoInput(true);            urlCon.getOutputStream().write("request content".getBytes("gbk"));            urlCon.getOutputStream().flush();            urlCon.getOutputStream().close();            BufferedReader in = new BufferedReader(new InputStreamReader(urlCon.getInputStream()));            String line;            while ((line = in.readLine()) != null) {                System.out.println(line);            }            // 增加自己的代码        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } catch (Exception e) {            e.printStackTrace();        }    }    public static void main(String[] args) {        HttpsURLConnectionTest httpsTest = new HttpsURLConnectionTest();        httpsTest.run();    }}/** * 重写三个方法 * @author Administrator * */class myX509TrustManager implements X509TrustManager {        public void checkClientTrusted(X509Certificate[] chain, String authType) {    }    public void checkServerTrusted(X509Certificate[] chain, String authType) {        System.out.println("cert: " + chain[0].toString() + ", authType: " + authType);    }    public X509Certificate[] getAcceptedIssuers() {        return null;    }}/** * 重写一个方法 * @author Administrator * */class myHostnameVerifier implements HostnameVerifier {    public boolean verify(String hostname, SSLSession session) {        System.out.println("Warning: URL Host: " + hostname + " vs. " + session.getPeerHost());        return true;    }}

以下摘自： 

 终于完成了博客备份的程序，自己一直想做的事情算是完成了。发扬怀疑一切的精神，真不放心把自己的帐号告诉其他的公司，让他们来备份。闲来无事，也为了让我玩实况累的发软的手体验一下敲代码的感觉，专心的做完了这个备份博客的程序。总共有300多行，功能其实也很简单，就是把每篇文章的网页保存起来 ，但第一次做这种网络程序，很多都要学习。下面列出几点收获： 

1，登陆需要使用SSL协议，似乎封装的太好了——只是把代码烤过来，很简单，现在也没懂是啥意思

2,使用Cookie。登录之后究竟用什么保存SessionID，头疼了很长时间。用IE进行登陆，把Cookie设成“提示”，于是所有的暗箱操作都见了阳光。这时才知道，几乎每个网页都会用Cookie存些东西，哪还有隐私。百度是必须用Cookie的，否则就无法登陆。这样有些过分了，应该提供一个选择。得到Cookie值后需要把“PASSPORTRETRYSTRING=deleted;”去掉，这个字段应该是用于防止重复提交的。如果不去掉，相当于没有登陆。去掉之后的Cookie值（主要是BDUUSS和BDUID）可以发送到服务器，这样就以登陆用户的身份查看博客了。

3，对于HTML代码应该可以用XML的方式来处理，不过我没有那个耐心，就用字符串的替代查找来实现了，效率不好，可以改进。

4，连接那部分代码借鉴了Google提供的博客访问的源代码，受益匪浅。百度没有相应的API，要不然我也不用这么麻烦。

5，还有许多细节的东西，比如文件读写啦。

6，看HTML代码真是头大！！！

为了取得信任我就把源代码贴出来，这也是我不愿意用那些商业软件的原因。商业软件，赚钱是最主要的，他不信任我，我也不信任他。而我，只不过图个安心和方便。

/** * 本程序可用于备份百度空间的文章。 * 18 hours costed. * niuys.  * 2007.7.11 */import java.io.*;import java.net.*;import java.security.GeneralSecurityException;import java.security.cert.X509Certificate;import java.util.*;import javax.net.ssl.HostnameVerifier;import javax.net.ssl.HttpsURLConnection;import javax.net.ssl.SSLContext;import javax.net.ssl.SSLSession;import javax.net.ssl.X509TrustManager;public class OpticalBackup {    // 把博客信息应编码    private String urlString = "https://passport.baidu.com/?login";    // 保存的目录    private String saveDir = "L:\\blogBackup";    // 博客的根路径    private String spaceRoot = "http://hi.baidu.com/niuys/blog/index/";    private String articleURLHead = "/niuys/blog/item/";    // parameters needed to log in.    Map parameters = new HashMap();    // 建立连接需要使用cookie提供的sessionID.    String cookieVal = null;    // Create an anonymous class to trust all certificates.    // This is bad style, you should create a separate class.    private X509TrustManager xtm = new X509TrustManager() {        public void checkClientTrusted(X509Certificate[] chain, String authType) {        }        public void checkServerTrusted(X509Certificate[] chain, String authType) {            // System.out.println("cert: " + chain[0].toString() + ", authType:            // "            // + authType);        }        public X509Certificate[] getAcceptedIssuers() {            return null;        }    };    // Create an class to trust all hosts    private HostnameVerifier hnv = new HostnameVerifier() {        public boolean verify(String hostname, SSLSession session) {            // System.out.println("hostname: " + hostname);            return true;        }    };    // In this function we configure our system with a less stringent    // hostname verifier and X509 trust manager. This code is    // executed once, and calls the static methods of HttpsURLConnection    public OpticalBackup() {        // The parameters needed to log on.        parameters.put("username", "保密");        parameters.put("password", "保密");        parameters.put("Submit", " 登录 ");        parameters.put("tpl", "sp");        parameters.put("tpl_reg", "sp");        parameters.put("u", "http://www.baidu.com/");        // check the saveDir        File dir = new File(saveDir);        if (!dir.exists()) {            dir.mkdir();        }        // Initialize the TLS SSLContext with        // our TrustManager        SSLContext sslContext = null;        try {            sslContext = SSLContext.getInstance("TLS");            X509TrustManager[] xtmArray = new X509TrustManager[] {xtm};            sslContext.init(null, xtmArray, new java.security.SecureRandom());        } catch (GeneralSecurityException e) {            // Print out some error message and deal with this exception            e.printStackTrace();        }        // Set the default SocketFactory and HostnameVerifier        // for javax.net.ssl.HttpsURLConnection        if (sslContext != null) {            HttpsURLConnection.setDefaultSSLSocketFactory(sslContext.getSocketFactory());        }        HttpsURLConnection.setDefaultHostnameVerifier(hnv);    }    // the whole process    public void run() {        try {            URL url = new URL(urlString);            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();            // Set properties of the connection            urlConnection.setDoInput(true);            urlConnection.setDoOutput(true);            urlConnection.setUseCaches(false);            urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");            // Form the POST parameters            StringBuilder content = new StringBuilder();            boolean first = true;            Set set = parameters.entrySet();            Iterator iterator = set.iterator();            Map.Entry parameter = (Map.Entry) iterator.next();            try {                while (parameter != null) {                    if (!first) {                        content.append("&");                    }                    content.append(URLEncoder.encode((String) parameter.getKey(), "UTF-8")).append("=");                    content.append(URLEncoder.encode((String) parameter.getValue(), "UTF-8"));                    first = false;                    parameter = (Map.Entry) iterator.next();                }            } catch (NoSuchElementException e) {                e.printStackTrace();            }            // send the POST request to server            OutputStream outputStream = null;            try {                outputStream = urlConnection.getOutputStream();                outputStream.write(content.toString().getBytes("utf-8"));                outputStream.flush();            } finally {                if (outputStream != null) {                    outputStream.close();                }            }            // Retrieve the output            InputStream inputStream = null;            StringBuilder outputBuilder = new StringBuilder();            try {                int responseCode = urlConnection.getResponseCode();                if (responseCode == HttpURLConnection.HTTP_OK) {                    inputStream = urlConnection.getInputStream();                } else {                    inputStream = urlConnection.getErrorStream();                }                String string;                if (inputStream != null) {                    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));                    while (null != (string = reader.readLine())) {                        outputBuilder.append(string).append('\n');                    }                }                // get the cookie value in the header filelds                Map map = urlConnection.getHeaderFields();                Collection collection = map.values();                Object[] values = collection.toArray();                // values[4].toString() is nedded .Otherwise,an exception                // throws. Direct class cast is forbidded.                cookieVal = (String) values[4].toString();                // "replaceAll()" requests that if "[" exits, "]" is nedded                // too.This is the diffrence from "replace()".                cookieVal = cookieVal.replace(']', ' ').replace("[PASSPORTRETRYSTRING=deleted; expires=Mon, 01 Jan 1970 00:00:00 GMT; path=/;", "");// remedy the first key from cookie            } finally {                if (inputStream != null) {                    inputStream.close();                }            }            // find all the URLs of the articles you write.            ArrayList pageURLs = findLinkers();            // save all the articles            for (int i = 0; i < pageURLs.size(); i++) {                savePage((String) pageURLs.get(i));            }        } catch (Exception e) {            e.printStackTrace();        }    }    // save the article with the URL    private void savePage(String pageURL) {        try {            // create the file to accept the output.The file's name is a part of            // the URL            File pageFile = new File(saveDir + "\\" + pageURL.substring(36));            // 增量备份            if (pageFile.exists())                return;            FileWriter fw = new FileWriter(pageFile);            // create the connection to the server,and get the results.            URL url = new URL(pageURL);            String content = getContentFromURL(url);            // write the contents to the file.            fw.write(content);            // flush the contents in the buffer.Without            // it,the file's content may be not completed.            fw.flush();            fw.close();        } catch (Exception e) {            e.printStackTrace();        }    }    // find all the articles' URL from the html code accepted from the server    private ArrayList findLinkers() {        // the index of the articles        int i = 0;        ArrayList linkers = new ArrayList();        URL url = null;        try {            while (true) {                url = new URL(spaceRoot + i);                System.out.println("url==" + url);                i++;// next index                // get the content from server                String content = getContentFromURL(url);                // Analyze the content.                ArrayList temp = getLinkerFromContent(content);                if (temp.isEmpty())// no article url exists                    return linkers;                linkers.addAll(temp);// combine the URLs            }        } catch (Exception e) {            e.printStackTrace();        }        return linkers;    }    private ArrayList getLinkerFromContent(String content) {        ArrayList linkerArray = new ArrayList();        String linker = null;        // The article's URL begins with "/niuys/blog/item/"        int index = content.indexOf(articleURLHead);        if (content.indexOf("暂无文章") > 0) {
     // 超过页数时会返回包含“暂无文章”的页,end            return linkerArray;        }        // deal with the content        while (index > 0) {            // get the whole URL            linker = content.substring(index, index + 46);            content = content.replace(linker, "");            index = content.indexOf(articleURLHead);            linker = "http://hi.baidu.com" + linker;            linkerArray.add(linker);            System.out.println("linker==" + linker);        }        return linkerArray;    }    private String getContentFromURL(URL url) throws Exception {        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();        // Set properties of the connection        urlConnection.setDoInput(true);        urlConnection.setDoOutput(true);        urlConnection.setUseCaches(false);        urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");        urlConnection.addRequestProperty("Cookie", cookieVal);        // Retrieve the output        InputStream inputStream = null;        StringBuilder outputBuilder = new StringBuilder();        int responseCode = urlConnection.getResponseCode();        if (responseCode == HttpURLConnection.HTTP_OK) {            inputStream = urlConnection.getInputStream();        } else {            inputStream = urlConnection.getErrorStream();        }        String string;        if (inputStream != null) {            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));            while (null != (string = reader.readLine())) {                outputBuilder.append(string).append('\n');            }            inputStream.close();            return outputBuilder.toString();        }        return "";    }    public static void main(String[] args) {        OpticalBackup backup = new OpticalBackup();        backup.run();    }}