这两天在读淘宝开源出来的DataX，想模仿它写一个离线数据交换组件。读了它读写Hbase的插件的源代码，觉得写得确实比我之前写得好。整理出来，放在这里，向优秀代码学习。关键的地方时它在处理异常的时候考虑的比我周全很多。

先是写Hbase的代码：

/** * (C) 2010-2011 Alibaba Group Holding Limited. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License  * version 2 as published by the Free Software Foundation.  *  */package com.taobao.datax.plugins.writer.hbasewriter;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.hbase.HTableDescriptor;import org.apache.hadoop.hbase.client.*;import org.apache.hadoop.hbase.util.Bytes;import java.io.IOException;import java.util.ArrayList;import java.util.List;public class HBaseProxy {	private Configuration config;	private HTable htable;	private HBaseAdmin admin;	private HTableDescriptor descriptor;		private static final int BUFFER_LINE = 1024;		private List
     
       buffer = new ArrayList
      
       (BUFFER_LINE);	private Put p;	public static HBaseProxy newProxy(String hbase_conf, String table) 			throws IOException {		return new HBaseProxy(hbase_conf, table);	}		private HBaseProxy(String hbase_conf, String tableName)			throws IOException {		Configuration conf = new Configuration();		conf.addResource(new Path(hbase_conf));		config = new Configuration(conf);		htable = new HTable(config, tableName);		admin = new HBaseAdmin(config);		descriptor = htable.getTableDescriptor();	}	public void setBufferSize(int bufferSize) throws IOException {		this.htable.setWriteBufferSize(bufferSize);	}		public void setHTable(String tableName) throws IOException {		this.htable = new HTable(config, tableName);	}	public void setAutoFlush(boolean autoflush) {		this.htable.setAutoFlush(autoflush);	}	public boolean check() throws IOException {		if (!admin.isMasterRunning()) {			throw new IllegalStateException("hbase master is not running!");		}		if (!admin.tableExists(htable.getTableName())) {			throw new IllegalStateException("hbase table " + Bytes.toString(htable.getTableName())					+ " is not existed!");		}		if (!admin.isTableAvailable(htable.getTableName())) {			throw new IllegalStateException("hbase table " + Bytes.toString(htable.getTableName())					+ " is not available!");		}		if (!admin.isTableEnabled(htable.getTableName())) {			throw new IllegalStateException("hbase table " + Bytes.toString(htable.getTableName())					+ " is disable!");		}		return true;	}	public void close() throws IOException {		htable.close();	}	public void deleteTable() throws IOException {		Scan s = new Scan();		ResultScanner scanner = htable.getScanner(s);		for (Result rr = scanner.next(); rr != null; rr = scanner.next()) {			htable.delete(new Delete(rr.getRow()));		}		scanner.close();	}	public void truncateTable() throws IOException {		admin.disableTable(htable.getTableName());		admin.deleteTable(htable.getTableName());		admin.createTable(descriptor);	}	public void flush() throws IOException {		if (!buffer.isEmpty()) {			htable.put(buffer);			buffer.clear();		}		htable.flushCommits();	}	public void prepare(byte[] rowKey) {		this.p = new Put(rowKey);    }		public Put add(byte[] family, byte[] qualifier, byte[] value) {		return this.p.add(family, qualifier, value);	}		public void insert() throws IOException {		buffer.add(this.p);		if (buffer.size() >= BUFFER_LINE) {			htable.put(buffer);			buffer.clear();		}	}}