在Eclipse中运行hadoop程序
1、下载hadoop-eclipse-plugin-1.2.1.jar，并将之复制到eclipse/plugins下。
2、打开map-reduce视图
在eclipse中，打开window——>open perspetive——>other，选择map/reduce。
3、选择Map/Reduce Locations标签页，新建一个Location
4、在project exploer中，可以浏览刚才定义站点的文件系统
5、准备测试数据，并上传到hdfs中。
liaoliuqingdeMacBook-Air:Downloads liaoliuqing$ hadoop fs -mkdir in
liaoliuqingdeMacBook-Air:Downloads liaoliuqing$ hadoop fs -copyFromLocal maxTemp.txt in
liaoliuqingdeMacBook-Air:Downloads liaoliuqing$ hadoop fs -ls in
Found 1 items
-rw-r--r-- 1 liaoliuqing supergroup 953 2014-12-14 09:47 /user/liaoliuqing/in/maxTemp.txt
其中maxTemp.txt的内容如下：
123456798676231190101234567986762311901012345679867623119010123456798676231190101234561+00121534567890356
123456798676231190101234567986762311901012345679867623119010123456798676231190101234562+01122934567890456
123456798676231190201234567986762311901012345679867623119010123456798676231190101234562+02120234567893456
123456798676231190401234567986762311901012345679867623119010123456798676231190101234561+00321234567803456
123456798676231190101234567986762311902012345679867623119010123456798676231190101234561+00429234567903456
123456798676231190501234567986762311902012345679867623119010123456798676231190101234561+01021134568903456
123456798676231190201234567986762311902012345679867623119010123456798676231190101234561+01124234578903456
123456798676231190301234567986762311905012345679867623119010123456798676231190101234561+04121234678903456
123456798676231190301234567986762311905012345679867623119010123456798676231190101234561+00821235678903456
6、准备map-reduce程序
程序请见http://blog.csdn.net/jediael_lu/article/details/37596469
7、运行程序
MaxTemperature.java——>run as——>run configuration
在arguments中填入输入及输出目录，开始run。
此处是在hdfs中运行程序，事实上也可以在本地文件系统中运行程序，此方法可以方便的用于程序调试。
如在参数中填入：
/Users/liaoliuqing/in /Users/liaoliuqing/out
即可。
8、以下是eclise console中的输出内容
14/12/14 10:52:05 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
14/12/14 10:52:05 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
14/12/14 10:52:05 WARN mapred.JobClient: No job jar file set. User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
14/12/14 10:52:05 INFO input.FileInputFormat: Total input paths to process : 1
14/12/14 10:52:05 WARN snappy.LoadSnappy: Snappy native library not loaded
14/12/14 10:52:06 INFO mapred.JobClient: Running job: job_local1815770300_0001
14/12/14 10:52:06 INFO mapred.LocalJobRunner: Waiting for map tasks
14/12/14 10:52:06 INFO mapred.LocalJobRunner: Starting task: attempt_local1815770300_0001_m_000000_0
14/12/14 10:52:06 INFO mapred.Task: Using ResourceCalculatorPlugin : null
14/12/14 10:52:06 INFO mapred.MapTask: Processing split: hdfs://localhost:9000/user/liaoliuqing/in/maxTemp.txt:0+953
14/12/14 10:52:06 INFO mapred.MapTask: io.sort.mb = 100
14/12/14 10:52:06 INFO mapred.MapTask: data buffer = 79691776/99614720
14/12/14 10:52:06 INFO mapred.MapTask: record buffer = 262144/327680
14/12/14 10:52:06 INFO mapred.MapTask: Starting flush of map output
14/12/14 10:52:06 INFO mapred.MapTask: Finished spill 0
14/12/14 10:52:06 INFO mapred.Task: Task:attempt_local1815770300_0001_m_000000_0 is done. And is in the process of commiting
14/12/14 10:52:06 INFO mapred.LocalJobRunner:
14/12/14 10:52:06 INFO mapred.Task: Task 'attempt_local1815770300_0001_m_000000_0' done.
14/12/14 10:52:06 INFO mapred.LocalJobRunner: Finishing task: attempt_local1815770300_0001_m_000000_0
14/12/14 10:52:06 INFO mapred.LocalJobRunner: Map task executor complete.
14/12/14 10:52:06 INFO mapred.Task: Using ResourceCalculatorPlugin : null
14/12/14 10:52:06 INFO mapred.LocalJobRunner:
14/12/14 10:52:06 INFO mapred.Merger: Merging 1 sorted segments
14/12/14 10:52:06 INFO mapred.Merger: Down to the last merge-pass, with 1 segments left of total size: 90 bytes
14/12/14 10:52:06 INFO mapred.LocalJobRunner:
14/12/14 10:52:06 INFO mapred.Task: Task:attempt_local1815770300_0001_r_000000_0 is done. And is in the process of commiting
14/12/14 10:52:06 INFO mapred.LocalJobRunner:
14/12/14 10:52:06 INFO mapred.Task: Task attempt_local1815770300_0001_r_000000_0 is allowed to commit now
14/12/14 10:52:06 INFO output.FileOutputCommitter: Saved output of task 'attempt_local1815770300_0001_r_000000_0' to hdfs://localhost:9000/user/liaoliuqing/out
14/12/14 10:52:06 INFO mapred.LocalJobRunner: reduce > reduce
14/12/14 10:52:06 INFO mapred.Task: Task 'attempt_local1815770300_0001_r_000000_0' done.
14/12/14 10:52:07 INFO mapred.JobClient: map 100% reduce 100%
14/12/14 10:52:07 INFO mapred.JobClient: Job complete: job_local1815770300_0001
14/12/14 10:52:07 INFO mapred.JobClient: Counters: 19
14/12/14 10:52:07 INFO mapred.JobClient: File Output Format Counters
14/12/14 10:52:07 INFO mapred.JobClient: Bytes Written=43
14/12/14 10:52:07 INFO mapred.JobClient: File Input Format Counters
14/12/14 10:52:07 INFO mapred.JobClient: Bytes Read=953
14/12/14 10:52:07 INFO mapred.JobClient: FileSystemCounters
14/12/14 10:52:07 INFO mapred.JobClient: FILE_BYTES_READ=450
14/12/14 10:52:07 INFO mapred.JobClient: HDFS_BYTES_READ=1906
14/12/14 10:52:07 INFO mapred.JobClient: FILE_BYTES_WRITTEN=135618
14/12/14 10:52:07 INFO mapred.JobClient: HDFS_BYTES_WRITTEN=43
14/12/14 10:52:07 INFO mapred.JobClient: Map-Reduce Framework
14/12/14 10:52:07 INFO mapred.JobClient: Reduce input groups=5
14/12/14 10:52:07 INFO mapred.JobClient: Map output materialized bytes=94
14/12/14 10:52:07 INFO mapred.JobClient: Combine output records=0
14/12/14 10:52:07 INFO mapred.JobClient: Map input records=9
14/12/14 10:52:07 INFO mapred.JobClient: Reduce shuffle bytes=0
14/12/14 10:52:07 INFO mapred.JobClient: Reduce output records=5
14/12/14 10:52:07 INFO mapred.JobClient: Spilled Records=16
14/12/14 10:52:07 INFO mapred.JobClient: Map output bytes=72
14/12/14 10:52:07 INFO mapred.JobClient: Total committed heap usage (bytes)=329252864
14/12/14 10:52:07 INFO mapred.JobClient: SPLIT_RAW_BYTES=118
14/12/14 10:52:07 INFO mapred.JobClient: Map output records=8
14/12/14 10:52:07 INFO mapred.JobClient: Combine input records=0
14/12/14 10:52:07 INFO mapred.JobClient: Reduce input records=8
