三、hbase JavaAPI

hbase是Java编写的，当然也提供了Java的API来操作hbase。

如果你是使用虚拟机来安装配置hbase那么你需要配置一下hostname，不然JavaAPI访问虚拟机的时候会无法连接，请参考：

https://www.cnblogs.com/lay2017/p/9953371.html

同时请注意关闭防火墙，如果你的虚拟机启动会默认开启防火墙的话，你需要关闭。

一、依赖

hbase客户端依赖如下：

<dependency><groupId>org.apache.hbase</groupId><artifactId>hbase-client</artifactId><version>1.2.0</version></dependency>

注意：hbase官方版本截止本文已经是2.1.1，但是这里使用1.2.0是由于官方文档并没有及时更新文档，所以对于client的使用你只能看到javadocs很不方便，亦或者你使用它文档的类的时候发现都是deprecated的线。

二、代码示例

以下的代码约200行，但内容并不复杂，仅有以下三块内容

1、在static块里面初始化了hbase的连接

2、main方法里面调用增删改查等JavaAPI接口，各个方法实现相应的内容

3、最后还有一个close方法

我们先看一下输出：

从输出内容我们看到，对表进行了删除、创建、列表查询，然后对表的单元格数据进行了新增、查询、遍历、删除

完整代码如下

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.*;import java.io.IOException;
import java.util.Arrays;/*** @Description java api* @Author lay* @Date 2018/11/12 13:10*/
public class HbaseJavaApiDemo {private static Configuration configuration;private static Connection connection;private static Admin admin;private static final String ENCODE = "UTF-8";static {// 创建configurationconfiguration = HBaseConfiguration.create();// 设置HBase的zk地址和端口configuration.set("hbase.zookeeper.quorum", "master");configuration.set("hbase.zookeeper.property.clientPort", "2181");try {connection = ConnectionFactory.createConnection(configuration);admin = connection.getAdmin();} catch (IOException e) {e.printStackTrace();}}public static void main(String[] args) throws Exception {try {String table = "t_user";String row = "row1";String columnFamily = "cf_name";String column = "firstName";String value = "lay";deleteTable(table);createOrOverrideTable(table, columnFamily);listTables();putData(table, row, columnFamily, column, value);getData(table, row, columnFamily, column);scanData(table);deleteData(table, row, columnFamily, column);} finally {close();}}/*** 创建表* @param table 表名* @param columnFamily 列簇* @throws IOException*/public static void createOrOverrideTable(String table, String columnFamily) throws IOException {TableName tableName = TableName.valueOf(table);HTableDescriptor tableDescriptor = new HTableDescriptor(tableName);// 添加一个列簇HColumnDescriptor hColumnDescriptor = new HColumnDescriptor(columnFamily);tableDescriptor.addFamily(hColumnDescriptor);// 存在则删除
        deleteTable(table);admin.createTable(tableDescriptor);System.out.println(table + " 表创建完成");}/*** 列出所有表* @throws IOException*/public static void listTables() throws IOException {HTableDescriptor[] hTableDescriptors = admin.listTables();System.out.println("列出所有的表：");for (HTableDescriptor t : hTableDescriptors) {System.out.println(t.getTableName());}}/*** 删除表* @param table 表名* @throws IOException*/public static void deleteTable(String table) throws IOException {TableName tableName = TableName.valueOf(table);if (admin.tableExists(tableName)) {admin.disableTable(tableName);admin.deleteTable(tableName);System.out.println(table + " 存在并执行删除");}}/*** 添加数据* @param table 表名* @param row 行* @param columnFamily 列簇* @param column 列* @param value 值* @throws IOException*/public static void putData(String table, String row, String columnFamily, String column, String value) throws IOException {TableName tableName = TableName.valueOf(table);Put put = new Put(row.getBytes(ENCODE));put.addColumn(columnFamily.getBytes(ENCODE), column.getBytes(ENCODE), value.getBytes(ENCODE));Table iTable = connection.getTable(tableName);iTable.put(put);iTable.close();System.out.println("数据添加完毕");}/*** 查询数据* @param table* @param row* @param columnFamily* @param column* @throws IOException*/public static void getData(String table, String row, String columnFamily, String column) throws IOException {TableName tableName = TableName.valueOf(table);Get get = new Get(row.getBytes(ENCODE));Table iTable = connection.getTable(tableName);Result result = iTable.get(get);byte[] data = result.getValue(columnFamily.getBytes(ENCODE), column.getBytes(ENCODE));System.out.println("查询的数据：" + new String(data));iTable.close();}/*** 删除数据* @param table* @param row* @param columnFamily* @param column* @throws IOException*/public static void deleteData(String table, String row, String columnFamily, String column) throws IOException {TableName tableName = TableName.valueOf(table);Delete delete = new Delete(row.getBytes(ENCODE));delete.addColumn(columnFamily.getBytes(ENCODE), column.getBytes(ENCODE));Table iTable = connection.getTable(tableName);iTable.delete(delete);iTable.close();System.out.println("数据删除完毕");}/*** 扫描数据* @param table* @throws IOException*/public static void scanData(String table) throws IOException {TableName tableName = TableName.valueOf(table);Scan scan = new Scan();Table iTable = connection.getTable(tableName);ResultScanner resultScanner = iTable.getScanner(scan);for (Result r : resultScanner) {Cell[] cells = r.rawCells();System.out.println("遍历的数据结果：");Arrays.stream(cells).forEach(cell -> {String value = new String(CellUtil.cloneValue(cell));System.out.println(value);});}iTable.close();}/*** 关闭admin和connection*/public static void close() {if (admin != null) {try {admin.close();} catch (IOException e) {throw new RuntimeException(e);}}if (connection != null) {try {connection.close();} catch (IOException e) {throw new RuntimeException(e);}}}}

转载于:https://www.cnblogs.com/lay2017/p/9953901.html