我的输入数据在 hdfs 中。我只是想进行字数统计，但略有不同。数据为json格式。所以每一行数据是：
{"author":"foo", "text": "hello"}
{"author":"foo123", "text": "hello world"}
{"author":"foo234", "text": "hello this world"}
我只想对“文本”部分中的单词进行字数统计。
我该怎么做呢？
到目前为止，我尝试了以下变体：
public static class TokenCounterMapper
extends Mapper<Object, Text, Text, IntWritable> {
private static final Log log = LogFactory.getLog(TokenCounterMapper.class);
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
try {
JSONObject jsn = new JSONObject(value.toString());
//StringTokenizer itr = new StringTokenizer(value.toString());
String text = (String) jsn.get("text");
log.info("Logging data");
log.info(text);
StringTokenizer itr = new StringTokenizer(text);
while (itr.hasMoreTokens()) {
word.set(itr.nextToken());
context.write(word, one);
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
但我收到此错误：
Error: java.lang.ClassNotFoundException: org.json.JSONException
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:820)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:865)
at org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:199)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:719)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
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:1093)
at org.apache.hadoop.mapred.Child.main(Child.java:249)