“`” a,b,c,d<\/p>\n
a,s,d,f<\/p>\n
d,f,g,c \u5c31\u5982\u6b64\u683c\u5f0f\uff0c<\/p>\n
\u4ee3\u7801\u5982\u4e0b\uff0c\u6bd4wordcount\u8fd8\u8981\u7b80\u5355\u4e00\u70b9\uff0c\u4ee3\u7801\u5dee\u4e0d\u591a\u7684<\/p>\n
\u00a0<\/p>\n
<pre><code class=""language-java"" lang=""java"">package make.hadoop.com.four_column;<\/p>\n
import java.io.IOException;<\/p>\n
import org.apache.hadoop.conf.Configuration;
\nimport org.apache.hadoop.conf.Configured;
\nimport org.apache.hadoop.fs.FileSystem;
\nimport org.apache.hadoop.fs.Path;
\nimport org.apache.hadoop.io.IntWritable;
\nimport org.apache.hadoop.io.LongWritable;
\nimport org.apache.hadoop.io.Text;
\nimport org.apache.hadoop.mapreduce.Job;
\nimport org.apache.hadoop.mapreduce.Mapper;
\nimport org.apache.hadoop.mapreduce.Reducer;
\nimport org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
\nimport org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
\nimport org.apache.hadoop.util.Tool;
\nimport org.apache.hadoop.util.ToolRunner;<\/p>\n
public class four_column extends Configured implements Tool {
\n \/\/ 1\u3001\u81ea\u5df1\u7684map\u7c7b
\n \/\/ 2\u3001\u7ee7\u627fmapper\u7c7b\uff0c<LongWritable, Text, Text,
\n \/\/ IntWritable>\u8f93\u5165\u7684key,\u8f93\u5165\u7684value\uff0c\u8f93\u51fa\u7684key,\u8f93\u51fa\u7684value
\n public static class MyMapper extends
\n Mapper<LongWritable, Text, Text, IntWritable> {
\n private IntWritable MapOutputkey = new IntWritable(1);
\n private Text MapOutputValue = new Text();<\/p>\n
@Override
\n protected void map(LongWritable key, Text value, Context context)
\n throws IOException, InterruptedException {<\/p>\n
String strs = value.toString();
\n \/\/ \u5206\u5272\u6570\u636e
\n String str_four = strs.split("","")[3];<\/p>\n
MapOutputValue.set(str_four);
\n System.out.println(str_four);
\n context.write(MapOutputValue, MapOutputkey);<\/p>\n
}
\n}
\n\/\/ 2\u3001\u81ea\u5df1\u7684reduce\u7c7b\uff0c\u8fd9\u91cc\u7684\u8f93\u5165\u5c31\u662fmap\u65b9\u6cd5\u7684\u8f93\u51fa
\npublic static class MyReduce extends
\n Reducer<Text, IntWritable, Text, IntWritable> {<\/p>\n
IntWritable countvalue = new IntWritable(1);<\/p>\n
@Override
\n \/\/ map\u7c7b\u7684map\u65b9\u6cd5\u7684\u6570\u636e\u8f93\u5165\u5230reduce\u7c7b\u7684group\u65b9\u6cd5\u4e2d\uff0c\u5f97\u5230<text,it(1,1)>,\u518d\u5c06\u8fd9\u4e2a\u6570\u636e\u8f93\u5165\u5230reduce\u65b9\u6cd5\u4e2d
\n protected void reduce(Text inputkey, Iterable<IntWritable> inputvalue,
\n Context context) throws IOException, InterruptedException {<\/p>\n
int sum = 0;<\/p>\n
for (IntWritable i : inputvalue) {
\n System.out.println(i.get());
\n sum = sum + i.get();
\n }
\n \/\/ System.out.println(""key: ""+inputkey + ""….""+sum);
\n countvalue.set(sum);
\n context.write(inputkey, countvalue);
\n }
\n}
\n\/\/ 3\u8fd0\u884c\u7c7b\uff0crun\u65b9\u6cd5\uff0c\u5728\u6d4b\u8bd5\u7684\u65f6\u5019\u4f7f\u7528main\u51fd\u6570\uff0c\u8c03\u7528\u8fd9\u4e2a\u7c7b\u7684run\u65b9\u6cd5\u6765\u8fd0\u884c<\/p>\n
\/**
\n * param args \u53c2\u6570\u662f\u63a5\u53d7main\u65b9\u5f97\u5230\u7684\u53c2\u6570\uff0c\u5728run\u4e2d\u4f7f\u7528
\n *\/
\npublic int run(String[] args) throws Exception {<\/p>\n
Configuration conf = new Configuration();<\/p>\n
Job job = Job.getInstance(this.getConf(), ""four_column"");<\/p>\n
\/\/ set mainclass
\n job.setJarByClass(four_column.class);<\/p>\n
\/\/ set mapper
\n job.setMapperClass(MyMapper.class);
\n job.setMapOutputKeyClass(Text.class);
\n job.setMapOutputValueClass(IntWritable.class);<\/p>\n
\/\/ set reducer
\n job.setReducerClass(MyReduce.class);
\n job.setOutputKeyClass(Text.class);
\n job.setOutputValueClass(IntWritable.class);<\/p>\n
\/\/ set path
\n Path inpath = new Path(args[0]);
\n FileInputFormat.setInputPaths(job, inpath);
\n Path outpath = new Path(args[1]);
\n FileOutputFormat.setOutputPath(job, outpath);
\n FileSystem fs = FileSystem.get(conf);
\n \/\/ \u5b58\u5728\u8def\u5f84\u5c31\u5220\u9664
\n if (fs.exists(outpath)) {
\n fs.delete(outpath, true);
\n }
\n job.setNumReduceTasks(1);<\/p>\n
boolean status = job.waitForCompletion(true);<\/p>\n
if (!status) {
\n System.err.println(""the job is error!!"");
\n }<\/p>\n
return status ? 0 : 1;<\/p>\n
}
\npublic static void main(String[] args) throws IOException,
\n ClassNotFoundException, InterruptedException {<\/p>\n
Configuration conf = new Configuration();<\/p>\n
int atatus;
\n try {
\n atatus = ToolRunner.run(conf, new four_column(), args);
\n System.exit(atatus);
\n } catch (Exception e) {
\n e.printStackTrace();
\n }<\/p>\n
}
\n}
\n<\/code><\/pre><\/p>\n
\u00a0<\/p>\n
<pre><code> "“`
\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
“`” a,b,c,d a,s,d,f d,f,g,c \u5c31\u5982\u6b64\u683c\u5f0f\uff0c \u4ee3\u7801\u5982\u4e0b\uff0c\u6bd4wo […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-47541","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47541","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=47541"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47541\/revisions"}],"predecessor-version":[{"id":47542,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47541\/revisions\/47542"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=47541"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=47541"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=47541"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}