Changes between Initial Version and Version 1 of NCHCCloudCourse100928_4_EXM2

Timestamp:

Sep 24, 2010, 6:20:03 PM (15 years ago)

Author:

waue

Comment:

--

NCHCCloudCourse100928_4_EXM2

@@ +1 @@
+
+{{{
+#!html
+<div style="text-align: center; color:#151B8D"><big style="font-weight: bold;"><big><big>
+Hadoop 進階課程 
+</big></big></big></div> <div style="text-align: center; color:#7E2217"><big style="font-weight: bold;"><big>
+範例練習
+</big></big></div>
+}}}
+
+ = [wiki:NCHCCloudCourse100928_4_EXM 上一關 < ] 第二關 [wiki:NCHCCloudCourse100928_4_EXM3 > 下一關] =
+
+
+ * HelloHadoopV2
+{{{
+#!java
+package org.nchc.hadoop;
+import java.io.IOException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+
+//      HelloHadoopV2
+//      說明： 
+//              此程式碼比HelloHadoop 增加 
+//              * 檢查輸出資料夾是否存在並刪除 
+//              * input 資料夾內的資料若大於兩個，則資料不會被覆蓋
+//              * map 與 reduce 拆開以利程式再利用
+//
+//      測試方法：
+//              將此程式運作在hadoop 0.20 平台上，執行：
+//              ---------------------------
+//              hadoop jar HelloHadoopV2.jar 
+//              ---------------------------
+//
+//      注意：
+//      1.      在hdfs 上來源檔案的路徑為 "/user/$YOUR_NAME/input"
+//              請注意必須先放資料到此hdfs上的資料夾內，且此資料夾內只能放檔案，不可再放資料夾
+//      2.      運算完後，程式將執行結果放在hdfs 的輸出路徑為 "/user/$YOUR_NAME/output-hh2"
+//              
+
+public class HelloHadoopV2 {
+
+
+        public static void main(String[] args) throws IOException,
+                        InterruptedException, ClassNotFoundException {
+
+                Configuration conf = new Configuration();
+                Job job = new Job(conf, "Hadoop Hello World 2");
+                job.setJarByClass(HelloHadoopV2.class);
+                // 設定 map and reduce 以及 Combiner class
+                job.setMapperClass(HelloMapperV2.class);
+                job.setCombinerClass(HelloReducerV2.class);
+                job.setReducerClass(HelloReducerV2.class);
+
+                // 設定map的輸出型態
+                job.setMapOutputKeyClass(Text.class);
+                job.setMapOutputValueClass(Text.class);
+                // 設定reduce的輸出型態
+                job.setOutputKeyClass(Text.class);
+                job.setOutputValueClass(Text.class);
+
+                FileInputFormat.addInputPath(job, new Path("/user/hadooper/input"));
+
+                FileOutputFormat.setOutputPath(job, new Path("/user/hadooper/output-hh2"));
+
+                // 呼叫checkAndDelete函式，檢查是否存在該資料夾，若有則刪除之
+                CheckAndDelete.checkAndDelete("/user/hadooper/output-hh2", conf);
+
+                boolean status = job.waitForCompletion(true);
+
+                if (status) {
+                        System.err.println("Integrate Alert Job Finished !");
+
+                } else {
+                        System.err.println("Integrate Alert Job Failed !");
+                        System.exit(1);
+                }
+        }
+}
+
+}}}
+
+ * HelloMapperV2
+
+{{{
+#!java
+package org.nchc.hadoop;
+import java.io.IOException;
+
+import org.apache.hadoop.io.LongWritable;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Mapper;
+
+public class HelloMapperV2 extends Mapper<LongWritable, Text, Text, Text> {
+
+        public void map(LongWritable key, Text value, Context context)
+                        throws IOException, InterruptedException {
+                context.write(new Text(key.toString()), value);
+        }
+
+}
+
+}}}
+
+ * HelloReducerV2
+
+{{{
+#!java
+package org.nchc.hadoop;
+import java.io.IOException;
+
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.mapreduce.Reducer;
+
+public class HelloReducerV2 extends Reducer<Text, Text, Text, Text> {
+        public void reduce(Text key, Iterable<Text> values, Context context)
+                        throws IOException, InterruptedException {
+
+                String str = new String("");
+                Text final_key = new Text();
+                Text final_value = new Text();
+                // 將key值相同的values，透過 && 符號分隔之
+                for (Text tmp : values) {
+                        str += tmp.toString() + " &&";
+                }
+
+                final_key.set(key);
+                final_value.set(str);
+
+                context.write(final_key, final_value);
+        }
+}
+
+}}}