Ik heb een voorbeeld van internet gebruikt en kan bestanden van Mongo naar HDFS overbrengen en andersom. Ik kon de exacte webpagina nu niet achterhalen. Maar het programma ziet er als volgt uit.
Je kunt hier een vonk uit halen en verder gaan.
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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.lib.output.FileOutputFormat;
import org.bson.BSONObject;
import org.bson.types.ObjectId;
import com.mongodb.hadoop.MongoInputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import com.mongodb.hadoop.util.MongoConfigUtil;
public class CopyFromMongodbToHDFS {
public static class ImportWeblogsFromMongo extends
Mapper<LongWritable, Text, Text, Text> {
public void map(Object key, BSONObject value, Context context)
throws IOException, InterruptedException {
System.out.println("Key: " + key);
System.out.println("Value: " + value);
String md5 = value.get("md5").toString();
String url = value.get("url").toString();
String date = value.get("date").toString();
String time = value.get("time").toString();
String ip = value.get("ip").toString();
String output = "\t" + url + "\t" + date + "\t" + time + "\t" + ip;
context.write(new Text(md5), new Text(output));
}
}
public static void main(String[] args) throws IOException,
InterruptedException, ClassNotFoundException {
Configuration conf = new Configuration();
MongoConfigUtil.setInputURI(conf,
"mongodb://127.0.0.1:27017/test.mylogs");
System.out.println("Configuration: " + conf);
@SuppressWarnings("deprecation")
Job job = new Job(conf, "Mongo Import");
Path out = new Path("/user/cloudera/test1/logs.txt");
FileOutputFormat.setOutputPath(job, out);
job.setJarByClass(CopyFromMongodbToHDFS.class);
job.setMapperClass(ImportWeblogsFromMongo.class);
job.setOutputKeyClass(ObjectId.class);
job.setOutputValueClass(BSONObject.class);
job.setInputFormatClass(MongoInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
job.setNumReduceTasks(0);
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}