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ClassNotFoundException for Hbase
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Apache HBase
Created 04-19-2016 11:38 AM
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Hi,
I have created the code as below to write a record into hbase table of 1.1.2 version. I have included all the jars present in 1.1.2 hbase lib folder but while executing that I am getting the Error Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/hbase/HBaseConfiguration
Code
package com.hp;
import java.io.IOExceptionimport org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.TableName; import org.apache.hadoop.hbase.client.Connection; import org.apache.hadoop.hbase.client.ConnectionFactory; import org.apache.hadoop.hbase.client.Get; import org.apache.hadoop.hbase.client.Put; import org.apache.hadoop.hbase.client.Result; import org.apache.hadoop.hbase.client.ResultScanner; import org.apache.hadoop.hbase.client.Scan; import org.apache.hadoop.hbase.client.Table; import org.apache.hadoop.hbase.util.Bytes; public class HbasePut { public static void main(String[] args) throws IOException {// You need a configuration object to tell the client where to connect. // When you create a HBaseConfiguration, it reads in whatever you've set // into your hbase-site.xml and in hbase-default.xml, as long as these can // be found on the CLASSPATH Configuration config = HBaseConfiguration.create(); // Next you need a Connection to the cluster. Create one. When done with it, // close it (Should start a try/finally after this creation so it gets closed // for sure but leaving this out for readibility's sake). Connection connection = ConnectionFactory.createConnection(config); try { // This instantiates a Table object that connects you to // the "myLittleHBaseTable" table (TableName.valueOf turns String into TableName instance). // When done with it, close it (Should start a try/finally after this creation so it gets // closed for sure but leaving this out for readibility's sake). Table table = connection.getTable(TableName.valueOf("myLittleHBaseTable")); try { // To add to a row, use Put. A Put constructor takes the name of the row // you want to insert into as a byte array. In HBase, the Bytes class has // utility for converting all kinds of java types to byte arrays. //In the below, we are converting the String "myLittleRow" into a byte array to // use as a row key for our update. Once you have a Put instance, you can // adorn it by setting the names of columns you want to update on the row, // the timestamp to use in your update, etc.If no timestamp, the server // applies current time to the edits. Put p = new Put(Bytes.toBytes("myLittleRow")); // To set the value you'd like to update in the row 'myLittleRow', specify // the column family, column qualifier, and value of the table cell you'd // like to update. The column family must already exist in your table // schema. The qualifier can be anything. All must be specified as byte // arrays as hbase is all about byte arrays. Lets pretend the table // 'myLittleHBaseTable' was created with a family 'myLittleFamily'. p.add(Bytes.toBytes("myLittleFamily"), Bytes.toBytes("cf1"),Bytes.toBytes("SomeValue")); // Once you've adorned your Put instance with all the updates you want to // make, to commit it do the following (The HTable#put method takes the // Put instance you've been building and pushes the changes you made into // hbase) table.put(p); // Now, to retrieve the data we just wrote. The values that come back are // Result instances. Generally, a Result is an object that will package up // the hbase return into the form you find most palatable. /*Get g = new Get(Bytes.toBytes("myLittleRow")); Result r = table.get(g); byte [] value = r.getValue(Bytes.toBytes("myLittleFamily"), Bytes.toBytes("cf1")); // If we convert the value bytes, we should get back 'Some Value', the // value we inserted at this location. String valueStr = Bytes.toString(value); System.out.println("GET: " + valueStr); // Sometimes, you won't know the row you're looking for. In this case, you // use a Scanner. This will give you cursor-like interface to the contents // of the table. To set up a Scanner, do like you did above making a Put // and a Get, create a Scan. Adorn it with column names, etc. Scan s = new Scan(); s.addColumn(Bytes.toBytes("myLittleFamily"), Bytes.toBytes("cf1")); ResultScanner scanner = table.getScanner(s); try { // Scanners return Result instances. // Now, for the actual iteration. One way is to use a while loop like so: for (Result rr = scanner.next(); rr != null; rr = scanner.next()) { // print out the row we found and the columns we were looking for System.out.println("Found row: " + rr); } // The other approach is to use a foreach loop. Scanners are iterable! // for (Result rr : scanner) { // System.out.println("Found row: " + rr); // } } finally { // Make sure you close your scanners when you are done! // Thats why we have it inside a try/finally clause scanner.close(); } */ // Close your table and cluster connection. } finally { if (table != null) table.close(); } } finally { connection.close(); } }
Created 04-19-2016 11:45 AM
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you may try adding /etc/hadoop/conf to the classpath
Created 04-19-2016 11:45 AM
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Did you tried exporting HADOOP_CLASSPATH variable in your env before running your java code?
Example:
export HADOOP_CLASSPATH=$HADOOP_CLASSPATH:/path/hbase<version>.jar
Created 04-20-2016 01:21 AM
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is it in bashrc you are telling me to add or in ambari
Created 04-20-2016 01:36 PM
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you simply need to execute this command on shell prompt before you run java -cp
bash# export HADOOP_CLASSPATH=$HADOOP_CLASSPATH:/path/hbase<version>.jar
bash# export CLASSPATH=$CLASSPATH:$HADOOP_CLASSPATH
Created 04-21-2016 03:24 PM
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Created 04-19-2016 11:51 AM
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If you've installed HBase client on your test environment, you could use this command to test your code:
export HBASE_CLASSPATH=$HBASE_CLASSPATH:<jar_compiled_using_your_code>
$HBASE_HOME/bin/hbase <package_name>.HbasePut
Created 04-20-2016 01:22 AM
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where exactly we can add, I mean in the bashrc or in ambari(in ambari means where we can change)
Created 04-20-2016 06:18 PM
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In the bash command line:
$ export HBASE_CLASSPATH=${HBASE_CLASSPATH}:<path_to_jar_compiled_using_your_code>
$ ${HBASE_HOME}/bin/hbase <package_name_of_your_class>.HbasePut
Created 04-19-2016 12:02 PM
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how are you running the job with "java " or "hadoop jar"?