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本文举例说明如何使用 org.apache.hadoop.security.UserGroupInformation 类在 Java 应用程序中对 Kerberos 主体进行身份验证。
以下代码段验证 user3主体（使用 user3.keytab文件）：
org.apache.hadoop.conf.Configuration conf = new org.apache.hadoop.conf.Configuration();
conf.set("hadoop.security.authentication", "Kerberos");
UserGroupInformation.setConfiguration(conf);
UserGroupInformation.loginUserFromKeytab(principal,keytab);
System.out.println("getting connection");
System.out.println("current user: "+UserGroupInformation.getCurrentUser());
System.out.println("login user: "+UserGroupInformation.getLoginUser());
示例代码实现的功能是：验证用户user3的keytab后，通过jdbc查询某张表的数据打印到控制台。
运行脚本hive.sh如下：
spark-submit --class iie.hadoop.permission.hive2 --master local /home/xdf/hive.jar user3 user3.keytab "select * from test1.table1"
程序完整代码如下：
import java.sql.*;
import org.apache.hadoop.security.UserGroupInformation; public class hive2 {
public static void main(String args[]) {
String principal = args[];
String keytab = args[];
String sql = args[];
try {
org.apache.hadoop.conf.Configuration conf = new org.apache.hadoop.conf.Configuration();
conf.set("hadoop.security.authentication", "Kerberos");
UserGroupInformation.setConfiguration(conf);
UserGroupInformation.loginUserFromKeytab(principal,keytab);
System.out.println("getting connection");
System.out.println("current user: "+UserGroupInformation.getCurrentUser());
System.out.println("login user: "+UserGroupInformation.getLoginUser()); Class.forName("org.apache.hive.jdbc.HiveDriver");
Connection con = DriverManager
.getConnection("jdbc:hive2://t163:10000/;principal=hive/t163@HADOOP.COM");
System.out.println("got connection");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(sql);// executeQuery会返回结果的集合，否则返回空值
System.out.println("打印输出结果：");
while (rs.next()) {
System.out.println(rs.getString());// 入如果返回的是int类型可以用getInt()
} con.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
运行结果如下：
[root@t161 xdf]# sh hive2.sh
// :: INFO security.UserGroupInformation: Login successful for user user3 using keytab file user3.keytab
getting connection
current user: user3@HADOOP.COM (auth:KERBEROS)
login user: user3@HADOOP.COM (auth:KERBEROS)
// :: INFO jdbc.Utils: Supplied authorities: t163:
// :: INFO jdbc.Utils: Resolved authority: t163:
got connection
打印输出结果：