HBase

HBase API操作

##1. 新建Java Project
新建一个Java Project后，引入HBase的所有jar包，将服务器上的hbase-site.xml拷贝到src目录

##2. 总体架构
表管理类操作模式：

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Configuration config = HBaseConfiguration.create();
HBaseAdmin admin = new HBaseAdmin(config);
......    
admin.doSomething();

表操作类模式：

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Configuration conf = HBaseConfiguration.create();
String tableName = ...;
HTable table = new HTable(conf, tableName);
......
table.doSomething();

###2.1 创建表

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public class CreateTableAction {
    /**
     * @param args
     * @throws IOException 
     * @throws ZooKeeperConnectionException 
     * @throws MasterNotRunningException 
     */
    public static void main(String[] args) throws MasterNotRunningException, ZooKeeperConnectionException, IOException {
        Configuration config = HBaseConfiguration.create();
        HBaseAdmin admin = new HBaseAdmin(config);
        
        TableName tableName = TableName.valueOf("table3");
        HTableDescriptor descriptor = new HTableDescriptor(tableName);
        HColumnDescriptor colDescriptor = new HColumnDescriptor("col1");
        descriptor.addFamily(colDescriptor);
        
        admin.createTable(descriptor);
    }
}

###2.2 删除表

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public class DeleteTableAction {
    /**
     * @param args
     * @throws IOException 
     * @throws ZooKeeperConnectionException 
     * @throws MasterNotRunningException 
     */
    public static void main(String[] args) throws MasterNotRunningException, ZooKeeperConnectionException, IOException {
        Configuration config = HBaseConfiguration.create();
        HBaseAdmin admin = new HBaseAdmin(config);
        
        String tableName = "table3";
        admin.disableTable(tableName);  // delete前必须先disable
        admin.deleteTable(tableName);  
    }
}

###2.3 列出所有表

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public class ListTablesAction {
    /**
     * @param args
     * @throws IOException 
     * @throws ZooKeeperConnectionException 
     * @throws MasterNotRunningException 
     */
    public static void main(String[] args) throws MasterNotRunningException, ZooKeeperConnectionException, IOException {
        Configuration config = HBaseConfiguration.create();
        HBaseAdmin admin = new HBaseAdmin(config);
        
        TableName[] tableNames = admin.listTableNames();
        for (TableName name : tableNames) {
            System.out.println("Table: " + name.getNameAsString());
        }
    }
}

###2.4 插入单条记录

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public class InsertOneRowAction {
    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        Configuration conf = HBaseConfiguration.create();
        String tableName = "table2";
        HTable table = new HTable(conf, tableName);
        Put put = new Put("row2".getBytes());
        put.add("col1".getBytes(), null, "2".getBytes()); // 第一个参数是列簇名，第二个参数是限定符（我的理解就是子列名），第三个参数是值
        table.put(put);
    }
}

在hbase shell查询

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hbase(main):004:0> scan 'table2'
ROW                                           COLUMN+CELL                                                                                                                         
 row2                                         column=col1:, timestamp=1400593778072, value=2                                                                                      
1 row(s) in 0.0700 seconds

PS: put方法不是线程安全的

###2.5 批量插入

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public class InsertRowsAction {
    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        Configuration conf = HBaseConfiguration.create();
        String tableName = "table2";
        HTable table = new HTable(conf, tableName);
        Put put3 = new Put("row3".getBytes());
        put3.add("col1".getBytes(), null, "3".getBytes());
        
        Put put4 = new Put("row4".getBytes());
        put4.add("col1".getBytes(), null, "4".getBytes());
        
        List<Put> puts = new ArrayList<Put>();
        puts.add(put3);
        puts.add(put4);
        
        table.put(puts);  //参数为List<Put>就是批量插入
        
        table.close();
    }
}

###2.5 单条查询

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public class GetOneRowAction {
    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        Configuration conf = HBaseConfiguration.create();
        String tableName = "table2";
        HTable table = new HTable(conf, tableName);
        Get get = new Get("row2".getBytes());
        Result result = table.get(get);
        System.out.println(new String(result.getRow()));                           // 获取row key
        System.out.println(new String(result.getValue("col1".getBytes(), null)));  // 获取指定字段的值
    }
}

###2.6 批量查询

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public class GetRowsAction {
    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        Configuration conf = HBaseConfiguration.create();
        String tableName = "table2";
        HTable table = new HTable(conf, tableName);
        
        System.out.println("======= 全表扫描 ========="); 
        Scan scan = new Scan();
        ResultScanner scaner = table.getScanner(scan);
        for (Result result : scaner) {
            System.out.println(new String(result.getRow()) + " : " + new String(result.getValue("col1".getBytes(), null)));                           // 获取row key
        } 
        
        System.out.println("======= 指定范围扫描 ========="); 
        Scan scan2 = new Scan("row2".getBytes());
        ResultScanner scaner2 = table.getScanner(scan2);
        for (Result result : scaner2) {
            System.out.println(new String(result.getRow()) + " : " + new String(result.getValue("col1".getBytes(), null)));                           // 获取row key
        } 
    }
}

输出结果：

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======= 全表扫描 =========
ro43 : 4
row2 : 2
row3 : 3
======= 指定范围扫描 =========
row2 : 2
row3 : 3

###2.7 删除

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public class DeleteOneRowAction {
    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        Configuration conf = HBaseConfiguration.create();
        String tableName = "table2";
        HTable table = new HTable(conf, tableName);
        Delete delete = new Delete("ro43".getBytes());
        table.delete(delete);
    }
}

执行前

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hbase(main):001:0> scan 'table2'
ROW                                           COLUMN+CELL                                      
 ro43                                         column=col1:, timestamp=1400594899049, value=4                                              
 row2                                         column=col1:, timestamp=1400593778072, value=2                                              
 row3                                         column=col1:, timestamp=1400594899049, value=3                                                                                      
3 row(s) in 0.2390 seconds

运行后

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hbase(main):002:0> scan 'table2'
ROW                                           COLUMN+CELL                                         
 row2                                         column=col1:, timestamp=1400593778072, value=2                                              
 row3                                         column=col1:, timestamp=1400594899049, value=3                                                                                      
2 row(s) in 0.0680 seconds

###2.8 更新

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public class UpdateOneRowAction {
    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        Configuration conf = HBaseConfiguration.create();
        String tableName = "table2";
        HTable table = new HTable(conf, tableName);
        Put put = new Put("row2".getBytes());
        put.add("col1".getBytes(), null, "2_new".getBytes()); // HBase的更新其实就是put一条row key一样的记录，HBase根据记录的时间戳可以知道这是哪条是最新的记录
        table.put(put);
    }
}

更新前

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hbase(main):002:0> scan 'table2'
ROW                                           COLUMN+CELL                                                                                                                         
 row2                                         column=col1:, timestamp=1400593778072, value=2                                                                                      
 row3                                         column=col1:, timestamp=1400594899049, value=3                                                                                      
2 row(s) in 0.0680 seconds

更新后

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hbase(main):003:0> scan 'table2'
ROW                                           COLUMN+CELL                                                                                                                         
 row2                                         column=col1:, timestamp=1400598165614, value=2_new                                                                                  
 row3                                         column=col1:, timestamp=1400594899049, value=3                                                                                      
2 row(s) in 0.0860 seconds