kerberos用Java循环认证代码示例

以下是一个使用Java实现Kerberos循环认证的示例代码：

import javax.security.auth.Subject;
import javax.security.auth.login.LoginContext;
import javax.security.auth.login.LoginException;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;
import javax.security.auth.kerberos.KerberosPrincipal;
import javax.security.auth.kerberos.KerberosTicket;
import javax.security.auth.kerberos.KeyTab;
import javax.security.auth.kerberos.KeyTabEntry;
import javax.security.auth.kerberos.KeyTabException;
import java.io.IOException;

public class KerberosAuthentication {

    private static final String SERVICE_PRINCIPAL = "HTTP/service-hostname@REALM";
    private static final String KEYTAB_PATH = "/path/to/keytab";

    public static void main(String[] args) {
        try {
            String username = "user";
            char[] password = "password".toCharArray();

            // create a LoginContext with a UsernamePasswordCallbackHandler
            LoginContext lc = new LoginContext("Kerberos", new UsernamePasswordCallbackHandler(username, password));

            // perform the authentication
            lc.login();

            // get the authenticated Subject
            Subject subject = lc.getSubject();

            // create a KerberosPrincipal for the service
            KerberosPrincipal servicePrincipal = new KerberosPrincipal(SERVICE_PRINCIPAL);

            // get the KerberosTicket for the service from the KeyTab
            KeyTab keyTab = KeyTab.getInstance(KEYTAB_PATH);
            KeyTabEntry keyTabEntry = keyTab.getEntry(servicePrincipal);
            KerberosTicket kerberosTicket = keyTabEntry.getServiceTicket(servicePrincipal);

            // add the KerberosTicket to the Subject
            subject.getPrivateCredentials().add(kerberosTicket);

            // use the authenticated Subject to perform actions on behalf of the user
            // ...

            // logout when done
            lc.logout();
        } catch (LoginException | KeyTabException | IOException e) {
            e.printStackTrace();
        }
    }

    private static class UsernamePasswordCallbackHandler implements CallbackHandler {

        private final String username;
        private final char[] password;

        public UsernamePasswordCallbackHandler(String username, char[] password) {
            this.username = username;
            this.password = password;
        }

        @Override
        public void handle(javax.security.auth.callback.Callback[] callbacks) throws UnsupportedCallbackException {
            for (javax.security.auth.callback.Callback callback : callbacks) {
                if (callback instanceof NameCallback) {
                    ((NameCallback) callback).setName(username);
                } else if (callback instanceof PasswordCallback) {
                    ((PasswordCallback) callback).setPassword(password);
                } else {
                    throw new UnsupportedCallbackException(callback, "Unsupported callback type");
                }
            }
        }
    }
}

该示例代码包括以下步骤：

1. 从用户名和密码创建一个LoginContext。
2. 使用LoginContext进行认证，并获取已认证的Subject。
3. 从KeyTab中获取服务的KerberosTicket，并将其添加到Subject的私有凭证中。
4. 使用已认证的Subject执行用户操作。
5. 在完成操作后使用LoginContext进行注销。

要使用该示例代码，请将以下值替换为实际值：

- SERVICE_PRINCIPAL：服务的Kerberos主体名称。
- KEYTAB_PATH：KeyTab的路径。
- username：要用于认证的用户名。
- password：要用于认证的密码。

该示例代码还使用了一个名为UsernamePasswordCallbackHandler的回调处理程序，该处理程序用于从用户名和密码提供的值中设置NameCallback和PasswordCallback。如果需要使用其他类型的回调，可以根据需要修改该处理程序。