昨天尝试把cas的java client端部署到另外一台机器，结果就有问题了。（localhost部署cas server和java client端参见：http://www.cnblogs.com/sunshineatnoon/p/4119565.html）
主要是client访问的时候报错：javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No subject alternative names present。
后来在stackoverflow上找到了解决办法：http://stackoverflow.com/questions/9331087/how-to-setup-ssl-for-cas-and-client-different-machines?rq=1
根据jasig文档对这个错误的解释：
Sample Alt Name Stack Trace javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No subject alternative names present In most cases this is a hostname/SSL certificate CN mismatch. This commonly happens when a self-signed certificate issued to localhost is placed on a machine that is accessed by IP address. It should be noted that generating a certificate with an IP address for a common name, e.g. CN=192.168.1.1,OU=Middleware,dc=vt,dc=edu, will not work in most cases where the client making the connection is Java. For example the Java CAS client will throw SSL errors on connecting to a CAS server secured with a certificate containing an IP address in the CN.
是由于生成的证书中域名（CN）和server的域名或者以后client端访问的域名不一致造成的，并且这里也说了，不能用ip地址当作生成证书时候的CN，只能用域名。
所以改变的方法就是用域名生成证书，并且配置client端电脑的hosts和lmhosts.sam文件解析服务器域名，具体步骤如下：
1. 编辑client端机器的C:\Windows\System32\Drivers\etc\hosts，添加一行：
your_ip(xxx.xxx.xxx.xxx) your_cn(sunshineatnoon.com)
2. 编辑client端机器的C:\Windows\System32\Drivers\etc\lmhosts.sam，添加一行：
your_ip(xxx.xxx.xxx.xxx) your_cn(sunshineatnoon.com)
3. 在server端所在的机器用keytool重新生成证书：
keytool -genkeypair -alias "tomcat" -keyalg "RSA" -keystore "g:\tomcat.keystore"
在回答"what‘s you name?"这个问题的时候回答上述你的域名：sunshineatnoon.com
4.配置server端机器的tomcat下%TOMCAT_PATH%/conf下的server.xml文件，参考http://www.cnblogs.com/sunshineatnoon/p/4064632.html的3(1)(2)，如果生成证书和以前的位置密码都没变，就不用重新配置了。
5.重新用文件InstallCert.java生成证书放到client端机器的$JAVA_HOME\jre\lib\security下，参考http://www.cnblogs.com/sunshineatnoon/p/4070750.html我所解决的第2个bug。
6.client端的java程序中请求ticket的url就由https://localhost:8443/cas/v1/tickets变成了https://sunshineatnoon.com:8443/cas/v1/tickets，改变后的client.java如下所示：
1 package cas;
2
3
4 import java.io.BufferedReader;
5 import java.io.BufferedWriter;
6 import java.io.IOException;
7 import java.io.InputStreamReader;
8 import java.io.OutputStreamWriter;
9 import java.net.MalformedURLException;
10 import java.net.URL;
11 import java.net.URLConnection;
12 import java.net.URLEncoder;
13
14 import javax.net.ssl.HttpsURLConnection;
15
16 public class Client {
17
18
19 public static void main(String... args) throws Exception
20 {
21 String username ="test01";
22 String password ="psw01";
23 validateFromCAS(username,password);
24 }
25
26 public static boolean validateFromCAS(String username, String password) throws Exception
27 {
28
29 //String url = "https://localhost:8443/cas/v1/tickets";
30 String url = "https://sunshineatnoon.com:8443/cas/v1/tickets";
31 try
32 {
33 HttpsURLConnection hsu = (HttpsURLConnection)openConn(url);
34 String s = URLEncoder.encode("username","UTF-8") + "=" + URLEncoder.encode("test01","UTF-8");
35 s+="&" +URLEncoder.encode("password","UTF-8") + "=" + URLEncoder.encode("psw01","UTF-8");
36
37 System.out.println(s);
38 OutputStreamWriter out = new OutputStreamWriter(hsu.getOutputStream());
39 BufferedWriter bwr = new BufferedWriter(out);
40 bwr.write(s);
41 bwr.flush();
42 bwr.close();
43 out.close();
44
45 String tgt = hsu.getHeaderField("location");
46 System.out.println( hsu.getResponseCode());
47 if(tgt != null && hsu.getResponseCode() == 201)
48 {
49 System.out.println(tgt);
50
51 System.out.println("Tgt is : " + tgt.substring( tgt.lastIndexOf("/") +1));
52 tgt = tgt.substring( tgt.lastIndexOf("/") +1);
53 bwr.close();
54 closeConn(hsu);
55
56
57 //String serviceURL = "http://localhost:8080/CasClient";
58 String serviceURL = "http://www.baidu.com";
59 String encodedServiceURL = URLEncoder.encode("service","utf-8") +"=" + URLEncoder.encode(serviceURL,"utf-8");
60 System.out.println("Service url is : " + encodedServiceURL);
61
62
63
64 String myURL = url+ "/"+ tgt ;
65 System.out.println(myURL);
66 hsu = (HttpsURLConnection)openConn(myURL);
67 out = new OutputStreamWriter(hsu.getOutputStream());
68 bwr = new BufferedWriter(out);
69 bwr.write(encodedServiceURL);
70 bwr.flush();
71 bwr.close();
72 out.close();
73
74 System.out.println("Response code is: " + hsu.getResponseCode());
75
76 BufferedReader isr = new BufferedReader( new InputStreamReader(hsu.getInputStream()));
77 String line;
78 System.out.println( hsu.getResponseCode());
79 while ((line = isr.readLine()) != null) {
80 System.out.println( line);
81 }
82 isr.close();
83 hsu.disconnect();
84 return true;
85
86 }
87 else
88 {
89 return false;
90 }
91
92
93 }
94 catch(MalformedURLException mue)
95 {
96 mue.printStackTrace();
97 throw mue;
98
99 }
100 catch(IOException ioe)
101 {
102 ioe.printStackTrace();
103 throw ioe;
104 }
105
106
107
108
109
110 }
111
112
113 static URLConnection openConn(String urlk) throws MalformedURLException, IOException
114 {
115
116 URL url = new URL(urlk);
117 HttpsURLConnection hsu = (HttpsURLConnection) url.openConnection();
118 hsu.setDoInput(true);
119 hsu.setDoOutput(true);
120 hsu.setRequestMethod("POST");
121 return hsu;
122
123
124 }
125
126
127 static void closeConn(HttpsURLConnection c)
128 {
129 c.disconnect();
130 }
131
132
133 }
注意红色那行改变的代码。
7.这时client端上的java client端应该就可以成功得到TGT和ST了。