收到错误:- 从映射键入不匹配的键:预期的org.apache.hadoop.io.Text，收到org.apache.

Question

我写了一个mapreduce作业来做日志文件分析。我的映射器将文本输出为键和值，并且我已经在我的驱动程序类中显式设置了映射输出类。

但我仍然收到错误：-从地图中键入密钥不匹配：预期的org.apache.hadoop.io.Text，收到org.apache.hadoop.io.LongWritable

public class CompositeUserMapper extends Mapper<LongWritable, Text, Text, Text> {
IntWritable a = new IntWritable(1);
//Text txt = new Text();
@Override
protected void map(LongWritable key, Text value,
        Context context)
        throws IOException, InterruptedException {
    String line = value.toString();
    Pattern p = Pattern.compile("bd{8}b");
    Matcher m = p.matcher(line);
    String userId = "";
    String CompositeId = "";
    if(m.find()){
        userId = m.group(1);
    }
     CompositeId = line.substring(line.indexOf("compositeId :")+13).trim();
     context.write(new Text(CompositeId),new Text(userId));

    // TODO Auto-generated method stub
    super.map(key, value, context);
}    

我的驱动程序类如下：-

public class CompositeUserDriver extends Configured implements Tool {
public static void main(String[] args) throws Exception {
    CompositeUserDriver wd = new CompositeUserDriver();
    int res = ToolRunner.run(wd, args);
    System.exit(res);
}
public int run(String[] arg0) throws Exception {
    // TODO Auto-generated method stub
    Job job=new Job();
    job.setJarByClass(CompositeUserDriver.class);
    job.setJobName("Composite UserId Count" );
    FileInputFormat.addInputPath(job, new Path(arg0[0]));
    FileOutputFormat.setOutputPath(job, new Path(arg0[1]));
    job.setMapperClass(CompositeUserMapper.class);
    job.setReducerClass(CompositeUserReducer.class);
    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(Text.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    return job.waitForCompletion(true) ? 0 : 1;
    //return 0;
}

}

请告知如何解决此问题。

Answer 1

从映射器代码中删除super.map(key, value, context);行：它调用父类的 map 方法，父类是返回传递给它的键和值的身份映射器，在这种情况下，键是文件开头的字节偏移量