如何使用java代码通过JDBC连接Impala(附Github源码)

Posted 2021-04-24 Hadoop实操

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1.文档编写目的

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访问Impala的方式很多（如：impala-shell、ODBC、JDBC、Beeline），也可以通过Hue的来访问。关于Beeline方式连接Impala可以参考前面的《》，本篇文章主要讲述如何使用JAVA代码通过JDBC的方式连接Kerberos和非Kerberos环境下的Impala。

• 内容概述

1.环境准备

2.非Kerberos及Kerberos环境连接示例

• 测试环境

1.Kerberos集群CDH5.11.2，OS为Redhat7.2

2.非Kerberos集群CDH5.13，OS为CentOS6.5

3.Impala JDBC驱动版本2.5.41.1061

• 前置条件

1.Kerberos和非Kerberos集群Impala服务正常

2.环境准备

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1.下载Impala JDBC驱动包

https://downloads.cloudera.com/connectors/impala_jdbc_2.5.41.1061.zip

2.创建Java工程jdbcdemo

创建工程时注意加入Hadoop的依赖包

<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-client</artifactId>
    <version>2.6.5</version>
</dependency>

将下载的Impala驱动包添加到jdbcdemo工程lib目录下，并加载到环境变量

3.非Kerberos环境

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1.示例代码

private static String JDBC_DRIVER = "com.cloudera.impala.jdbc41.Driver";
private static String CONNECTION_URL ="jdbc:impala://54.255.237.128:21050/";

static {
    try {
        Class.forName(JDBC_DRIVER);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {
    Connection connection = null;
    ResultSet rs = null;
    PreparedStatement ps = null;
    try {
        connection = DriverManager.getConnection(CONNECTION_URL);
        ps = connection.prepareStatement("select * from test_table");
        rs = ps.executeQuery();
        while (rs.next()) {
            System.out.println(rs.getInt(1) + "-------" + rs.getString(2));
        }

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        JDBCUtils.disconnect(connection, rs, ps);
    }
}

2.示例代码运行

4.Kerberos环境

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在Kerberos环境下的Impala需要准备Kerberos的krb5.conf文件及keytab文件。

• krb5.conf配置，直接将集群的krb5.conf文件拷贝至本地开发环境下

# Configuration snippets may be placed in this directory as well
includedir /etc/krb5.conf.d/

[logging]
 default = FILE:/var/log/krb5libs.log
 kdc = FILE:/var/log/krb5kdc.log
 admin_server = FILE:/var/log/kadmind.log

[libdefaults]
 dns_lookup_realm = false
 ticket_lifetime = 24h
 renew_lifetime = 7d
 forwardable = true
 rdns = false
 default_realm = CLOUDERA.COM
 #default_ccache_name = KEYRING:persistent:%{uid}

[realms]
 CLOUDERA.COM = {
  kdc = 54.179.148.25
  admin_server = 54.179.148.25
 }

keytab文件生成

[ec2-user@ip-172-31-22-86 ~]$ sudo kadmin.local
Authenticating as principal hive/[e-mail] with password.
kadmin.local:  xst -norandkey -k fayson.keytab [e-mail] 

1.示例代码

private static String JDBC_DRIVER = "com.cloudera.impala.jdbc41.Driver";
private static String CONNECTION_URL = "jdbc:impala://13.229.60.149:21050/default;AuthMech=1;KrbRealm=CLOUDERA.COM;KrbHostFQDN=ip-172-31-26-102.ap-southeast-1.compute.internal;KrbServiceName=impala";

static {
    try {
        Class.forName(JDBC_DRIVER);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {
    //登录Kerberos账号
    try {
        System.setProperty("java.security.krb5.conf", "/Volumes/Transcend/keytab/krb5.conf");
        Configuration configuration = new Configuration();
        configuration.set("hadoop.security.authentication" , "Kerberos");
        UserGroupInformation. setConfiguration(configuration);
        UserGroupInformation.loginUserFromKeytab("[e-mail]", "/Volumes/Transcend/keytab/fayson.keytab");
        System.out.println(UserGroupInformation.getCurrentUser() + "------" + UserGroupInformation.getLoginUser());

        UserGroupInformation loginUser = UserGroupInformation.getLoginUser();

        loginUser.doAs(new PrivilegedAction<Object>(){

            public Object run() {
                Connection connection = null;
                ResultSet rs = null;
                PreparedStatement ps = null;
                try {
                    Class.forName(JDBC_DRIVER);
                    connection = DriverManager.getConnection(CONNECTION_URL);
                    ps = connection.prepareStatement("select * from test_table");
                    rs = ps.executeQuery();
                    rs = ps.executeQuery();
                    while (rs.next()) {
                        System.out.println(rs.getInt(1));
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    JDBCUtils.disconnect(connection, rs, ps);
                }
                return null;
            }
        });
    } catch (IOException e) {
        e.printStackTrace();
    }
}

具体JDBC的URL参数说明参考：

http://www.cloudera.com/documentation/other/connectors/impala-jdbc/latest/Cloudera-JDBC-Driver-for-Impala-Install-Guide.pdf

2.示例代码运行

https://github.com/javaxsky/cdhproject

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