Author: gcrieloue Date: 2010-03-18 16:56:06 +0100 (Thu, 18 Mar 2010) New Revision: 262 Log: Ajout d'un client simple pour HBase. Added: trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/MyLittleHBaseClient.java Modified: trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/Main.java Modified: trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/Main.java =================================================================== --- trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/Main.java 2010-03-18 14:35:50 UTC (rev 261) +++ trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/Main.java 2010-03-18 15:56:06 UTC (rev 262) @@ -0,0 +1,11 @@ +package org.nuiton.mapstoragemanager.plugins.hbase; + +import org.apache.hadoop.hbase.MasterNotRunningException; + +public class Main{ + + public static void main(String[] args) throws MasterNotRunningException { + HBase hb = new HBase(); + } + +} \ No newline at end of file Added: trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/MyLittleHBaseClient.java =================================================================== --- trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/MyLittleHBaseClient.java (rev 0) +++ trunk/msm-hbase/src/main/java/org/nuiton/mapstoragemanager/plugins/hbase/MyLittleHBaseClient.java 2010-03-18 15:56:06 UTC (rev 262) @@ -0,0 +1,108 @@ +package org.nuiton.mapstoragemanager.plugins.hbase; + +import java.io.IOException; + +import org.apache.hadoop.hbase.HBaseConfiguration; +import org.apache.hadoop.hbase.HColumnDescriptor; +import org.apache.hadoop.hbase.HTableDescriptor; +import org.apache.hadoop.hbase.client.Get; +import org.apache.hadoop.hbase.client.HBaseAdmin; +import org.apache.hadoop.hbase.client.HTable; +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.util.Bytes; + + +// Class that has nothing but a main. +// Does a Put, Get and a Scan against an hbase table. +public class MyLittleHBaseClient { + 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 + HBaseConfiguration config = new HBaseConfiguration(); + String tableName = "myLittleHBaseTable"; + /* + HTableDescriptor hTableDescriptor = new HTableDescriptor(tableName); + //hTableDescriptor.addFamily(new HColumnDescriptor("myColumnFamily")); + HBaseAdmin hBaseAdmin = new HBaseAdmin(config); + + try{ + hBaseAdmin.createTable(hTableDescriptor); + hBaseAdmin.enableTable(tableName); + } + catch(org.apache.hadoop.hbase.TableExistsException e){ + System.out.println("Table "+tableName+" already created."); + } +*/ + // This instantiates an HTable object that connects you to + // the "myLittleHBaseTable" table. + HTable table = new HTable(config, tableName); + System.out.println("HTable table = new HTable(config, tableName);"); + + // 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("someQualifier"), + Bytes.toBytes("Some Value")); + + // 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("someQualifier")); + // 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("someQualifier")); + 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(); + } + } +}