您好我正在使用map-reduce代码来解析我的XML文件并在输出中创建CSV。
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
public class XMLParseMR {
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
public static String outputFile = null;
private Text word = new Text();
private JAXBC jax = new JAXBC();
public void map(LongWritable key, Text value, Context context) throws
IOException, InterruptedException {
String document = value.toString();
System.out.println("XML : "+ document);
try {
ConnectHome ch = jax.convertJAXB(document);
jax.convertCSV(ch, outputFile);
}
catch (JAXBException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = new Job(conf, "wordcount");
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.setMapperClass(Map.class);
conf.set("xmlinput.start", "<ConnectHome>");
conf.set("xmlinput.end", "</ConnectHome>");
job.setInputFormatClass(XMLInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
Map.outputFile = args[1];
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.waitForCompletion(true);
}
}
我还有一个名为Connect_Home的类，我在其中解析使用JAXB提取数据的数据。但是当我运行代码时，我得到以下错误：
WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments.
Applications should implement Tool for the same.
WARN mapred.JobClient: No job jar file set. User classes may not be found. See
JobConf(Class) or JobConf#setJar(String).
INFO input.FileInputFormat: Total input paths to process : 1
INFO util.NativeCodeLoader: Loaded the native-hadoop library
WARN snappy.LoadSnappy: Snappy native library not loaded
INFO mapred.JobClient: Running job: job_201303121556_0011
mapred.JobClient: map 0% reduce 0%
INFO mapred.JobClient: Task Id : attempt_201303121556_0011_m_000000_0, Status :
FAILED
java.lang.RuntimeException: java.lang.ClassNotFoundException: XMLParseMR$Map
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1004)
org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:217)
at javax.security.auth.Subject.doAs(Subject.java:396)
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1278)
at org.apache.hadoop.mapred.Child.main(Child.java:260)
Caused by: java.lang.ClassNotFoundException: XMLParseMR$Map
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at sun.misc.Launcher$AppClassLoader.loadCl
INFO mapred.JobClient: Task Id : attempt_201303121556_0011_m_000000_1, Status :
FAILED
java.lang.RuntimeException: java.lang.ClassNotFoundException:
XMLParseMR$Map
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1004)
at
org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:217)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:602)
at javax.security.auth.Subject.doAs(Subject.java:396)
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1278)
at org.apache.hadoop.mapred.Child.main(Child.java:260)
Caused by: java.lang.ClassNotFoundException: XMLParseMR$Map
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at sun.misc.Launcher$AppClassLoader.loadCl
INFO mapred.JobClient: Task Id : attempt_201303121556_0011_m_000000_2, Status :
FAILED
java.lang.RuntimeException: java.lang.ClassNotFoundException: XMLParseMR$Map
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1004)
at
org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:217)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:602)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:323)
at org.apache.hadoop.mapred.Child$4.run(Child.java:266)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1278)
at org.apache.hadoop.mapred.Child.main(Child.java:260)
Caused by: java.lang.ClassNotFoundException: XMLParseMR$Map
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at sun.misc.Launcher$AppClassLoader.loadCl
INFO mapred.JobClient: Job complete: job_201303121556_0011
INFO mapred.JobClient: Counters: 7INFO mapred.JobClient: Job Counters
INFO mapred.JobClient: SLOTS_MILLIS_MAPS=20097
INFO mapred.JobClient: Total time spent by all reduces waiting after reserving
slots (ms)=0
INFO mapred.JobClient: Total time spent by all maps waiting after reserving
slots (ms)=0
INFO mapred.JobClient: Launched map tasks=4
INFO mapred.JobClient: Data-local map tasks=4
INFO mapred.JobClient: SLOTS_MILLIS_REDUCES=0
INFO mapred.JobClient: Failed map tasks=1
答案 0 :(得分：1)
错误消息：
WARN mapred.JobClient: No job jar file set. User classes may not be found. See
JobConf(Class) or JobConf#setJar(String).
告诉您，该作业未正确设置。您可以通过在设置作业时调用setJarByClass()让Hadoop自行确定JAR，而不是按名称设置JAR：
Job job = new Job(conf, "wordcount");
job.setJarByClass(XMLParseMR.class);
它将根据您的班级名称设置Job's JAR。之后你的工作应该正确运行，上面提到的错误信息将会消失。