Hadoop之自定义输入数据（一）

默认KeyValueTextInputFormat的数据输入是通过，空格来截取，区分key和value的值，这里我们通过自定义来实现通过 “,”来截取。
一，准备文件数据：

2，自定义MyFileInputFormat类：

    import java.io.IOException;
    import org.apache.hadoop.io.Text;
    import org.apache.hadoop.mapreduce.InputSplit;
    import org.apache.hadoop.mapreduce.RecordReader;
    import org.apache.hadoop.mapreduce.TaskAttemptContext;
    import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
    import org.apache.hadoop.mapreduce.lib.input.KeyValueLineRecordReader;
    public class MyFileInputFormat extends FileInputFormat<Text, Text> {
        @Override
        public RecordReader<Text, Text> createRecordReader(InputSplit split, TaskAttemptContext context)
                throws IOException, InterruptedException {

             context.setStatus(split.toString());
             return new MyLineRecordReader(context.getConfiguration());
        }

    }

3，自定义MyLineRecordReader类，并修改其中的截取方法：

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.LineRecordReader;
public class MyLineRecordReader extends RecordReader<Text, Text> {
    public static final String KEY_VALUE_SEPERATOR = "mapreduce.input.keyvaluelinerecordreader.key.value.separator";

    private final LineRecordReader lineRecordReader;

    private byte separator = (byte) ',';

    private Text innerValue;

    private Text key;

    private Text value;

    public Class getKeyClass() {
        return Text.class;
    }

    public MyLineRecordReader(Configuration conf)
                throws IOException {

                lineRecordReader = new LineRecordReader();
                String sepStr = conf.get(KEY_VALUE_SEPERATOR, ",");
                this.separator = (byte) sepStr.charAt(0);
              }

    public void initialize(InputSplit genericSplit, TaskAttemptContext context) throws IOException {
        lineRecordReader.initialize(genericSplit, context);
    }

    public static int findSeparator(byte[] utf, int start, int length, byte sep) {
        for (int i = start; i < (start + length); i++) {
            if (utf[i] == sep) {
                return i;
            }
        }
        return -1;
    }

    public static void setKeyValue(Text key, Text value, byte[] line, int lineLen, int pos) {
        if (pos == -1) {
            key.set(line, 0, lineLen);
            value.set("");
        } else {
            key.set(line, 0, pos);
            value.set(line, pos + 1, lineLen - pos - 1);
        }
    }

    /** Read key/value pair in a line. */
    public synchronized boolean nextKeyValue() throws IOException {
        byte[] line = null;
        int lineLen = -1;
        if (lineRecordReader.nextKeyValue()) {
            innerValue = lineRecordReader.getCurrentValue();
            line = innerValue.getBytes();
            lineLen = innerValue.getLength();
        } else {
            return false;
        }
        if (line == null)
            return false;
        if (key == null) {
            key = new Text();
        }
        if (value == null) {
            value = new Text();
        }
        int pos = findSeparator(line, 0, lineLen, this.separator);
        setKeyValue(key, value, line, lineLen, pos);
        return true;
    }

    public Text getCurrentKey() {
        return key;
    }

    public Text getCurrentValue() {
        return value;
    }

    public float getProgress() throws IOException {
        return lineRecordReader.getProgress();
    }

    public synchronized void close() throws IOException {
        lineRecordReader.close();
    }

}

4，测试类的书写：

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
public class Test{
    public static void main(String[] args) {
        try {
            Configuration conf = new Configuration();
            String[] paths = new GenericOptionsParser(conf, args).getRemainingArgs();
            if(paths.length < 2){
                throw new RuntimeException("usage <input> <output>");
            }
            Job job = Job.getInstance(conf, "wordcount2");
            job.setJarByClass(Test.class);
            job.setInputFormatClass(MyFileInputFormat.class);
            //job.setInputFormatClass(TextInputFormat.class);
            job.setMapOutputKeyClass(Text.class);
            job.setMapOutputValueClass(Text.class);
            //job.setOutputFormatClass(TextOutputFormat.class);
            FileInputFormat.addInputPaths(job, paths[0]);//同时写入两个文件的内容
            FileOutputFormat.setOutputPath(job, new Path(paths[1] + System.currentTimeMillis()));//整合好结果后输出的位置
            System.exit(job.waitForCompletion(true) ? 0 : 1);//执行job

        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

5,结果：