四、HBase Java API 操作

1、Java代码测试是否连接成功连接以及简单的增删改查操作：

public class CreateHBase {
    Connection conn = null;
    Admin admin = null;

    /**
     * 创建名称空间
     *
     * @throws Exception
     */
    @Test
    public void getConnection() throws Exception {
        // 取得一个数据库连接的配置参数对象
        Configuration conf = HBaseConfiguration.create();

        // 设置连接参数：HBase数据库所在的主机IP
        conf.set("hbase.zookeeper.quorum", "192.168.99.100");
        或
        conf.set("hbase.zookeeper.quorum", "myhbase");

        // 设置连接参数：HBase数据库使用的端口
        conf.set("hbase.zookeeper.property.clientPort", "2181");

        // 取得一个数据库连接对象
        conn = ConnectionFactory.createConnection(conf);

        // 数据库元数据操作对象
        admin = conn.getAdmin();
       // createTable();
       // getTablesName();
        addData("student", "1001", "", "tom");
    }

    /**
     * 创建表
     */
    public void createTable() {

        // 数据表表名
        String tableNameString = "student";
        String columnName = "info";

        // 新建一个数据表表名对象
        TableName tableName = TableName.valueOf(tableNameString);

        // 如果需要新建的表已经存在
        try {
            if (admin.tableExists(tableName)) {
                System.out.println("表已经存在！");
            } else {
                // 数据表描述对象
                HTableDescriptor tableDescriptor = new HTableDescriptor(tableName);

                // 列族描述对象
                HColumnDescriptor columnDescriptor = new HColumnDescriptor(columnName);

                // 在数据表中新建一个列族
                tableDescriptor.addFamily(columnDescriptor);

                // 新建数据表
                admin.createTable(tableDescriptor);
                System.out.println("创建表成功!");
            }
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("创建表失败!");
        }
    }

  /**
     * 获取所有表名
     */
    public void getTablesName() {
        TableName[] tableNames;
        try {
            tableNames = admin.listTableNames();
            for (TableName tableName : tableNames) {
                System.out.println("已存在的表名：" + tableName);
            }
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("获取所有表名失败！");
        }
    }

   /**
     * 删除表
     * @param tableNameStr
     */
    public void deleteTable(String tableNameStr) {
        TableName tableName = TableName.valueOf(tableNameStr);
        try {
            if (admin.tableExists(tableName)) {
                admin.disableTable(tableName);
                admin.deleteTable(tableName);
                System.out.println("表删除成功！");
            } else {
                System.out.println("表不存在！");
            }
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("表删除失败！");
        }
    }

   /**
     * 删除一条记录
     * @param tableName
     * @param rowKey
     */
    public void deleteRecord(String tableName, String rowKey) {
        try {
            Table table = conn.getTable(TableName.valueOf(tableName));
            Delete del = new Delete(rowKey.getBytes());
            table.delete(del);
            System.out.println(tableName + " 表删除数据成功！");
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println(tableName + " 表删除数据失败！");
        }
    }

    /**
     * 插入一条数据
     * @param tableName
     * @param rowKey
     * @param columnFamily
     * @param qualifier
     * @param value
     * @return
     */
    public boolean insertRecord(String tableName, String rowKey,
                                String columnFamily, String qualifier, String value) {
        try {
            Table table = conn.getTable(TableName.valueOf(tableName));
            Put put = new Put(rowKey.getBytes());
            put.addColumn(columnFamily.getBytes(), qualifier.getBytes(), value.getBytes());
            table.put(put);
            System.out.println("插入数据成功！！！");
            return true;
        } catch (IOException e) {
            System.out.println("插入数据失败！！！");
        }
        return false;
    }

   /**
     * 查询一条记录
     * @param tableName
     * @param rowKey
     * @return
     */
    public Result getOneRecord(String tableName, String rowKey) {
        try {
            Table table = conn.getTable(TableName.valueOf(tableName));
            Get get = new Get(rowKey.getBytes());
            Result rs = table.get(get);
            System.out.println(tableName + " 表获取数据成功！");
            for (Cell cell : rs.rawCells()) {
                System.out.println("family:"+Bytes.toString(cell.getFamilyArray(),cell.getFamilyOffset(),cell.getFamilyLength()));
                System.out.println("qualifier:"+Bytes.toString(cell.getQualifierArray(),cell.getQualifierOffset(),cell.getQualifierLength()));
                System.out.println("value:"+Bytes.toString(cell.getValueArray(),cell.getValueOffset(),cell.getValueLength()));
                System.out.println("Timestamp:"+cell.getTimestamp());
                System.out.println("---------------");
            }
            return rs;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

[
family:info
qualifier:age
value:23
Timestamp:1539588568063
---------------
family:info
qualifier:name
value:tom
Timestamp:1539588567538
---------------
keyvalues={1001/info:age/1539588568063/Put/vlen=2/seqid=0, 
           1001/info:name/1539588567538/Put/vlen=3/seqid=0}
]


    /**
     * 查询所有的记录
     * @param tableName
     * @return
     */
    public List<Result> getAllRecords(String tableName) {
        ResultScanner scanner = null;
        List<Result> list = new ArrayList<>();
        try {
            Table table = conn.getTable(TableName.valueOf(tableName));
            Scan scan = new Scan();
            scanner = table.getScanner(scan);
            Iterator<Result> iterator = scanner.iterator();

            while (iterator.hasNext()) {
                Result rs = iterator.next();
                list.add(rs);
                for (Cell cell : rs.rawCells()) {
                    System.out.println("Family: " + Bytes.toString(cell.getFamilyArray(), cell.getFamilyOffset(), cell.getFamilyLength()));
                    System.out.println("Qualifier: " + Bytes.toString(cell.getQualifierArray(), cell.getQualifierOffset(), cell.getQualifierLength()));
                    System.out.println("Value: " + Bytes.toString(cell.getValueArray(), cell.getValueOffset(), cell.getValueLength()));
                    System.out.println("----------------------");
                }
            }
            System.out.println(list);
            scanner.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (!Objects.isNull(scanner)) {
                scanner.close();
            }
        }
        return list;
    }