数据操纵语言

1. GET请求用来根据行键从表中获取一行数据

因为HBase行键即索引，所以GET的性能很快。GET也可以指定需要获取数据的列族、列、时间范围和版本号等。
关键一句：Get get = new Get(Bytes.toBytes(“1001”));

public class GetValue {
    public static void main(String[] args) {
        Configuration configuration = HBaseConfiguration.create();
        configuration.set("hbase.zookeeper.quorum", "121.37.70.214");
        configuration.set("hbase.master", "121.37.70.214:16010");
        configuration.set("hbase.zookeeper.property.clientPort", "2181");
        try {
            Connection connection = ConnectionFactory.createConnection(configuration);
            Table table = connection.getTable(TableName.valueOf("bigdata:stu"));
            Get get = new Get(Bytes.toBytes("1001"));
            Result result = table.get(get);
            byte[] value = result.getValue(Bytes.toBytes("info1"), Bytes.toBytes("name"));
            byte[] value1 = result.getValue(Bytes.toBytes("info1"), Bytes.toBytes("age"));
            String name = Bytes.toString(value);
            String age = Bytes.toString(value1);
            System.out.println("name:" + name + ", age:" + age);
            table.close();
            connection.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2. Delete用来删除数据

可以删除整行、列族、列以及某个时间戳之前的所有版本的数据，使用简单。
关键一句：Delete delete = new Delete(Bytes.toBytes(“1001”));

public class DeleteValue {
    public static void main(String[] args) {
        Configuration configuration = HBaseConfiguration.create();
        configuration.set("hbase.zookeeper.quorum", "121.37.70.214");
        configuration.set("hbase.master", "121.37.70.214:16010");
        configuration.set("hbase.zookeeper.property.clientPort", "2181");

        try {
            Connection connection = ConnectionFactory.createConnection(configuration);
            Table table = connection.getTable(TableName.valueOf("bigdata:stu"));

            Delete delete = new Delete(Bytes.toBytes("1001"));
            delete.addFamily(Bytes.toBytes("info1"));
            table.delete(delete);
            System.out.println("data had been deleted...");
            table.close();
            connection.close();

        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

3. Put用来向表中插入数据

关键一句：Put put = new Put(Bytes.toBytes(“1001”));

public class PutValue {
    public static void main(String[] args) {


        // 获取配置文件
        Configuration config = HBaseConfiguration.create();
        config.set("hbase.zookeeper.quorum", "121.37.70.214");
        config.set("hbase.master", "121.37.70.214:16010");
        config.set("hbase.zookeeper.property.clientPort", "2181");

        try {
            Connection connection = ConnectionFactory.createConnection(config);
            Table table = connection.getTable(TableName.valueOf("bigdata:stu"));

            // 插入数据
            Put put = new Put(Bytes.toBytes("1001"));

            put.addColumn(Bytes.toBytes("info"), Bytes.toBytes("name"), Bytes.toBytes("zhangsan"));
            put.addColumn(Bytes.toBytes("info"), Bytes.toBytes("age"), Bytes.toBytes("21"));

            table.put(put);
            System.out.println("Data has been updated!");
            table.close();
            admin.close();
            connection.close();

        } catch (IOException e) {
            e.printStackTrace();
        }


    }
}

4. Scan读取多行数据

Scan与Get都可以用来查询数据，区别是Scan可以用来读取多行数据，Scan结果的遍历类似于关系型数据库的游标。
关键一句：Scan scan = new Scan();

public class ScanTable {
    public static void main(String[] args) {

        Configuration configuration = HBaseConfiguration.create();
        configuration.set("hbase.zookeeper.quorum", "112.124.0.168");
        configuration.set("hbase.master", "112.124.0.168:16010");
        configuration.set("hbase.zookeeper.property.clientPort", "2181");

        try {
            Connection connection = ConnectionFactory.createConnection(configuration);
            Table table = connection.getTable(TableName.valueOf("bigdata:test"));

            Scan scan = new Scan();
            scan.addFamily(Bytes.toBytes("info1"));

            // Getting the scan result
            ResultScanner results = table.getScanner(scan);
            for (Result result : results) {
                Cell[] cells = result.rawCells();
                for (Cell cell: cells){
                    // get RowKey
                    System.out.println("行键：" + Bytes.toString(CellUtil.cloneRow(cell)));

                    System.out.println("列族：" + Bytes.toString(CellUtil.cloneFamily(cell)));
                    System.out.println("列：" + Bytes.toString(CellUtil.cloneQualifier(cell)));
                    System.out.println("值：" + Bytes.toString(CellUtil.cloneValue(cell)));
                }
            }

            results.close();
            table.close();
            connection.close();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}