Changes between Version 1 and Version 2 of waue/2010/0125

Timestamp:

Jan 25, 2010, 5:13:29 PM (15 years ago)

Author:

waue

Comment:

--

waue/2010/0125

@@ -184 +184 @@
 package hbase020;
 
-// from hbase website 
+
+
+// 說明：
+// 此程式首先建立table, 然後put一個資料後
+// 用get 方法取得資料，最後用scan方法取出整個資料表
+// 
+// 參考： 程式碼改編自
 // http://hadoop.apache.org/hbase/docs/current/api/org/apache/.接.
 //  hadoop/hbase/client/package-summary.html#package_description
@@ -205 +211 @@
 // Does a Put, Get and a Scan against an hbase table.
 public class MyLittleHBaseClient {
+        
+        private static String table_name = "mytable";
+        
+        private static String the_row = "myLittleRow";
+        
+        private static String column_family = "family";
+        
+        private static String column_qualifier = "someQualifier";
+        
+        private static String cell_value = "somvalue";
+        
+        
+        
         public static void createHBaseTable(String tablename) throws IOException {
                 // HTableDescriptor contains the name of an HTable, and its column
@@ -214 +233 @@
                 // etc.
                 // HTableDescriptor 透過 add() 方法來加入Column family
-                htd.addFamily(new HColumnDescriptor("content:"));
+                htd.addFamily(new HColumnDescriptor(column_family+":"));
                 // HBaseConfiguration 能接收 hbase-site.xml 的設定值
                 HBaseConfiguration config = new HBaseConfiguration();
@@ -230 +249 @@
                 admin.createTable(htd);
         }
+
         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
+                // can be found on the CLASSPATH
+                
                 HBaseConfiguration config = new HBaseConfiguration();
 
+                // create table automatically
+                createHBaseTable(table_name);
+                
                 // This instantiates an HTable object that connects you to
                 // the "myLittleHBaseTable" table.
-                HTable table = new HTable(config, "myLittleHBaseTable");
+                HTable table = new HTable(config, table_name);
+
 
                 // To add to a row, use Put. A Put constructor takes the name of the row
@@ -254 +278 @@
                 // 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"));
+                Put p = new Put(Bytes.toBytes(the_row));
 
                 // To set the value you'd like to update in the row 'myRow', specify the
@@ -264 +288 @@
                 // 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"));
+                p.add(Bytes.toBytes(column_family), Bytes.toBytes(column_qualifier),
+                                Bytes.toBytes(cell_value));
 
                 // Once you've adorned your Put instance with all the updates you want
@@ -280 +304 @@
                 // up
                 // the hbase return into the form you find most palatable.
-                Get g = new Get(Bytes.toBytes("myLittleRow"));
+                Get g = new Get(Bytes.toBytes(the_row));
                 Result r = table.get(g);
-                byte[] value = r.getValue(Bytes.toBytes("myLittleFamily"), Bytes
-                                .toBytes("someQualifier"));
+                byte[] value = r.getValue(Bytes.toBytes(column_family), Bytes
+                                .toBytes(column_qualifier));
                 // If we convert the value bytes, we should get back 'Some Value', the
                 // value we inserted at this location.
@@ -296 +320 @@
                 // and a Get, create a Scan. Adorn it with column names, etc.
                 Scan s = new Scan();
-                s.addColumn(Bytes.toBytes("myLittleFamily"), Bytes
-                                .toBytes("someQualifier"));
+                s.addColumn(Bytes.toBytes(column_family), Bytes
+                                .toBytes(column_qualifier));
                 ResultScanner scanner = table.getScanner(s);
                 try {
@@ -303 +327 @@
                         // 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()) {
+                        for (Result rr : scanner) {
                                 // print out the row we found and the columns we were looking
                                 // for