mapreduce 只使用Mapper往多个hbase表中写数据

只使用Mapper不使用reduce会大大减少mapreduce程序的运行时间。

有时候程序会往多张hbase表写数据。

所以有如题的需求。

下面给出的代码，不是可以运行的代码，只是展示driver中需要进行的必要项设置，mapper类需要实现的接口，map函数需要的参数以及函数内部的处理方式。

实现过程比较曲折，只贴代码：

class Qos2HbaseDriver extends Configured implements Tool
{
    private static Logger logger = LoggerFactory
            .getLogger(Qos2HbaseDriver.class);
    private static final int DEFAULT_NUM_REDUCE = 0;

    /**
     * args[0]输入hdfs文件路径，args[1]输出表
     */

    @Override
    public int run(String[] args) throws Exception
    {
        Configuration conf = HBaseConfiguration.create();
        conf.set("output", args[1]);//输出表1
        conf.set("output2", args[2]);//输出表2

        Job job = Job.getInstance(conf);
        job.setJobName("iplane_Qos2Hbase");
        job.setMapperClass(Qos2HbaseMapper.class);
        FileInputFormat.setInputPaths(job, args[0]);
        job.setMapOutputKeyClass(ImmutableBytesWritable.class);
        job.setMapOutputValueClass(Put.class);
        job.setOutputFormatClass(MultiTableOutputFormat.class);

        TableMapReduceUtil.addDependencyJars(job);
        TableMapReduceUtil.addDependencyJars(job.getConfiguration());
        job.setJarByClass(Qos2Hbase.class);

        // 设置reduce个数，可调节
        int numberReduceTasks = 0;
        job.setNumReduceTasks(numberReduceTasks);
        boolean b = job.waitForCompletion(true);
        if (!b)
        {
            logger.error("工作错误！");
            return -1;
        }
        return 0;
    }
}

/**
 * @ClassName: Qos2HbaseMapper
 * @Description: 将结果入Hbase库的mapper类
 * @author xxx
 * @date 2014-9-16 下午1:18:49
 *
 */
class Qos2HbaseMapper extends
        Mapper<LongWritable, Text, ImmutableBytesWritable, Put>
{
    private static Logger logger = LoggerFactory
            .getLogger(Qos2HbaseMapper.class);

    @Override
    public void map(LongWritable key, Text line, Context context)
            throws IOException, InterruptedException
    {
        String output = context.getConfiguration().get("output");
        String output2 = context.getConfiguration().get("output2");

        // 组装rowkey：ip_ip
        StringBuffer rowkeySb = "aaaa";

        Put put = null;
        String family = "d";
        String qualifier = "";
        // 直接将结果存入hbase
        long ts = System.currentTimeMillis();
        put = new Put(Bytes.toBytes(rowkeySb.toString()));

        qualifier = "del";
        put.add(Bytes.toBytes(family), Bytes.toBytes(qualifier), ts,
                Bytes.toBytes(values[6]));// 组装一条数据
            if (!put.isEmpty())
            {
                ImmutableBytesWritable ib = new ImmutableBytesWritable();
                ib.set(Bytes.toBytes(output));
                context.write(ib, put);// 将结果存入hbase表
            }      

        // 存历史表
        rowkeySb.append(rowkeySeparator).append(myDate);
        put = new Put(Bytes.toBytes(rowkeySb.toString()));
        qualifier = "del";
        put.add(Bytes.toBytes(family), Bytes.toBytes(qualifier), ts,
                Bytes.toBytes(values[6]));// 组装一条数据
            if (!put.isEmpty())
            {
                ImmutableBytesWritable ib = new ImmutableBytesWritable();
                ib.set(Bytes.toBytes(output2));
                context.write(ib, put);// 将结果存入hbase表
            }

    }
}