Java Example Code

Development Description

This example applies only to MRS HBase.

Prerequisites
A datasource connection has been created and bound to a queue on the DLI management console.

Hard-coded or plaintext passwords pose significant security risks. To ensure security, encrypt your passwords, store them in configuration files or environment variables, and decrypt them when needed.

Code implementation

Import dependencies.

Maven dependency involved

          
               <dependency>
  <groupId>org.apache.spark</groupId>
  <artifactId>spark-sql_2.11</artifactId>
  <version>2.3.2</version>
</dependency>

Import dependency packages.

          
               import org.apache.spark.sql.SparkSession;

Create a session.

        
             parkSession = SparkSession.builder().appName("datasource-HBase-MRS").getOrCreate();

Connecting to data sources through SQL APIs

For clusters with Kerberos authentication disabled

Create a table to connect to an MRS HBase data source and set connection parameters.

          
               sparkSession.sql("CREATE TABLE testhbase(id STRING, location STRING, city STRING) using hbase OPTIONS('ZKHost'='10.0.0.63:2181','TableName'='hbtest','RowKey'='id:5','Cols'='location:info.location,city:detail.city') ");

Insert data.

          
               sparkSession.sql("insert into testhbase values('12345','abc','xxx')");

Query data.

          
               sparkSession.sql("select * from testhbase").show();

Response

For clusters with Kerberos authentication enabled

Create a table to connect to an MRS HBase data source and set connection parameters.

          
               sparkSession.sql("CREATE TABLE testhbase(id STRING, location STRING, city STRING) using hbase OPTIONS('ZKHost'='10.0.0.63:2181','TableName'='hbtest','RowKey'='id:5','Cols'='location:info.location,city:detail.city,'krb5conf'='./krb5.conf','keytab'='./user.keytab','principal'='krbtest') ");

If Kerberos authentication is enabled, you need to set three more parameters, as listed in Table 1.

**Table 1** Parameter description
Parameter and Value	Description
'krb5conf' = './krb5.conf'	Path of the krb5.conf file.
'keytab'='./user.keytab'	Path of the keytab file.
'principal' ='krbtest'	Authentication username.

For details about how to obtain the krb5.conf and keytab files, see Completing Configurations for Enabling Kerberos Authentication.

Insert data.

          
               sparkSession.sql("insert into testhbase values('95274','abc','Hongkong')");

Query data.

          
               sparkSession.sql("select * from testhbase").show();

Submitting a Spark job
1. Generate a JAR package based on the code file and upload the package to DLI.
2. (Optional) Add the krb5.conf and user.keytab files to the dependency files of the job when creating a Spark job in an MRS cluster with Kerberos authentication enabled. Skip this step if Kerberos authentication is not enabled for the cluster. Figure 1 shows how to add the files.
  Figure 1 Adding dependency files
3. In the Spark job editor, select the corresponding dependency module and execute the Spark job.
  If the Spark version is 2.3.2 (will be offline soon) or 2.4.5, specify the Module to sys.datasource.hbase when you submit a job.
  
  If the Spark version is 3.1.1, you do not need to select a module. Configure Spark parameters (--conf).
  spark.driver.extraClassPath=/usr/share/extension/dli/spark-jar/datasource/hbase/*
  
  spark.executor.extraClassPath=/usr/share/extension/dli/spark-jar/datasource/hbase/*
  
  For details about how to submit a job on the console, see the description of the table "Parameters for selecting dependency resources" in Creating a Spark Job.
  
  For details about how to submit a job through an API, see the description of the modules parameter in Table 2 "Request parameters" in Creating a Batch Processing Job.

Complete Example Code

Connecting to data sources through SQL APIs

Complete example code for the cluster with Kerberos authentication disabled

        
             import org.apache.spark.sql.SparkSession;
 
public class java_mrs_hbase {
 
    public static void main(String[] args) {
        //create a SparkSession session
        SparkSession sparkSession = SparkSession.builder().appName("datasource-HBase-MRS").getOrCreate();
 
        sparkSession.sql("CREATE TABLE testhbase(id STRING, location STRING, city STRING) using hbase OPTIONS('ZKHost'='10.0.0.63:2181','TableName'='hbtest','RowKey'='id:5','Cols'='location:info.location,city:detail.city') ");
 
        //*****************************SQL model***********************************
        sparkSession.sql("insert into testhbase values('95274','abc','Hongkong')");
        sparkSession.sql("select * from testhbase").show();
 
        sparkSession.close();
    }
}

Complete example code for the cluster with Kerberos authentication enabled

        
         
           
           
             import org.apache.spark.SparkContext;
import org.apache.spark.SparkFiles;
import org.apache.spark.sql.SparkSession;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class Test_HBase_SparkSql_Kerberos {

    private static void copyFile(File src,File dst) throws IOException {
        InputStream input  = null;
        OutputStream output = null;
        try {
            input = new FileInputStream(src);
            output = new FileOutputStream(dst);
            byte[] buf = new byte[1024];
            int bytesRead;
            while ((bytesRead = input.read(buf)) > 0) {
                output.write(buf, 0, bytesRead);
            }
        } finally { 
            input.close();
            output.close();
        }
    }

    public static void main(String[] args) throws InterruptedException, IOException {
        SparkSession sparkSession = SparkSession.builder().appName("Test_HBase_SparkSql_Kerberos").getOrCreate();
        SparkContext sc = sparkSession.sparkContext();
        sc.addFile("obs://xietest1/lzq/krb5.conf");
        sc.addFile("obs://xietest1/lzq/user.keytab");
        Thread.sleep(20);

        File krb5_startfile = new File(SparkFiles.get("krb5.conf"));
        File keytab_startfile = new File(SparkFiles.get("user.keytab"));
        String path_user = System.getProperty("user.dir");
        File keytab_endfile = new File(path_user + "/" + keytab_startfile.getName());
        File krb5_endfile = new File(path_user + "/" + krb5_startfile.getName());
        copyFile(krb5_startfile,krb5_endfile);
        copyFile(keytab_startfile,keytab_endfile);
        Thread.sleep(20);

        /**
         * Create an association table for the DLI association Hbase table
         */
        sparkSession.sql("CREATE TABLE testhbase(id string,booleanf boolean,shortf short,intf int,longf long,floatf float,doublef double) " +
                "using hbase OPTIONS(" +
                "'ZKHost'='10.0.0.146:2181'," +
                "'TableName'='hbtest'," +
                "'RowKey'='id:100'," +
                "'Cols'='booleanf:CF1.booleanf,shortf:CF1.shortf,intf:CF1.intf,longf:CF2.longf,floatf:CF1.floatf,doublef:CF2.doublef'," +
                "'krb5conf'='" + path_user + "/krb5.conf'," +
                "'keytab'='" + path_user+ "/user.keytab'," +
                "'principal'='krbtest') ");

        //*****************************SQL model***********************************
        sparkSession.sql("insert into testhbase values('newtest',true,1,2,3,4,5)");
        sparkSession.sql("select * from testhbase").show();
        sparkSession.close();
    }
}

            

          

        
       