Hadoop學習：Map/Reduce初探與小Demo實現
一、 概念知識介紹
Hadoop MapReduce是一個用於處理海量數據的分布式計算框架。這個框架攻克了諸如數據分布式存儲、作業調度、容錯、機器間通信等復雜問題，能夠使沒有並行 處理或者分布式計算經驗的project師，也能非常輕松地寫出結構簡單的、應用於成百上千臺機器處理大規模數據的並行分布式程序。
Hadoop MapReduce基於“分而治之”的思想，將計算任務抽象成map和reduce兩個計算過程，能夠簡單理解為“分散運算—歸並結果”的過程。一個 MapReduce程序首先會把輸入數據切割成不相關的若幹鍵/值對（key1/value1）集合。這些鍵/值對會由多個map任務來並行地處理。 MapReduce會對map的輸出（一些中間鍵/值對key2/value2集合）依照key2進行排序，排序是用memcmp的方式對key在內存中 字節數組比較後進行升序排序。並將屬於同一個key2的全部value2組合在一起作為reduce任務的輸入，由reduce任務計算出終於結果並輸出 key3/value3。作為一個優化。同一個計算節點上的key2/value2會通過combine在本地歸並。基本流程例如以下：
Hadoop和單機程序計算流程對照：
常計算任務的輸入和輸出都是存放在文件中的，而且這些文件被存放在Hadoop分布式文件系統HDFS（Hadoop Distributed File System）中，系統會盡量調度計算任務到數據所在的節點上執行，而不是盡量將數據移動到計算節點上。降低大量數據在網絡中傳輸，盡量節省帶寬消耗。
應用程序開發者普通情況下須要關心的是圖中灰色的部分，單機程序須要處理數據讀取和寫入、數據處理；Hadoop程序須要實現map和 reduce。而數據讀取和寫入、map和reduce之間的傳輸數據、容錯處理等由Hadoop MapReduce和HDFS自己主動完畢。
二、 開發環境搭建
Map/Reduce程序依賴Hadoop集群，另外Eclipse須要安裝依賴的hadoop包。
Hadoop集群搭建：參考Hadoop 2.2.0集群搭建
1. 安裝、配置Eclipse
在官網下載合適的Eclipse，將hadoop開發所依賴的插件jar包復制到eclipse的安裝目錄plugins下。下載地址參考：hadoop2.2.0開發依賴的jar包，當然也能夠自己編譯。
啟動eclipse，選擇Window—>Prefrances，若出現例如以下Hadoop Map/Reduce說明插件成功安裝
2. 配置DFS，主要是數據文件的輸入輸出管理。
Window—>Open Perspective—>other—>Map/Reduce，顯示Map/Reduce視圖。點擊Map/Reduce Locations 的小象圖標。新建Hadoop Location，輸入例如以下：
項目視圖會出現DFS Location。用來管理輸入、輸出數據文件。
須要配置hadoop安裝目錄：新建Map/Reduceproject單擊Configure Hadoop install direction。輸入hadoop的安裝路徑。
右鍵單擊DFS Location下的空目錄上傳一個文本文件，然後刷新，若文件出現了則說明環境配置成功。
三、 編程模型
MapReduce編程模型的原理是：利用一個輸入key/value pair集合來產生一個輸出的key/value pair集合。
MapReduce庫的用戶用兩個函數表達這個計算：Map和Reduce。
用戶自己定義的Map函數接受一個輸入的key/value pair值，然後產生一個中間key/value pair值的集合。
MapReduce庫把全部具有同樣中間key值I的中間value值集合在一起後傳遞給reduce函數。
用戶自己定義的Reduce函數接受一個中間key的值I和相關的一個value值的集合。Reduce函數合並這些value值，形成一個較小的 value值的集合。一般的。每次Reduce函數調用僅僅產生0或1個輸出value值。
通常我們通過一個叠代器把中間value值提供給Reduce函 數，這樣我們就能夠處理無法所有放入內存中的大量的value值的集合。
四、 小樣例
1. 數據準備
以Tomcat日誌為例。日誌格式例如以下：
127.0.0.1,-,-,[08/May/2014:13:42:40 +0800],GET / HTTP/1.1,200,11444 127.0.0.1,-,-,[08/May/2014:13:42:42 +0800],GET /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurrentClassPlanVO HTTP/1.1,204,- 127.0.0.1,-,-,[08/May/2014:13:42:42 +0800],GET /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurClassPlanVO HTTP/1.1,204,- 127.0.0.1,-,-,[08/May/2014:13:42:47 +0800],GET /jygl/jaxrs/right/isValidUserByType/1-admin-superadmin HTTP/1.1,200,20 127.0.0.1,-,-,[08/May/2014:13:42:47 +0800],GET /jygl/jaxrs/right/getUserByLoginName/admin HTTP/1.1,200,198 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/right_login2home?loginName=admin&password=superadmin&type=1 HTTP/1.1,200,2525 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/style/style.css HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/js/tree.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/js/jquery.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/js/frame.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/images/logo.png HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/images/leftmenu_bg.gif HTTP/1.1,404,1105 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/menuList.jsp HTTP/1.1,200,47603 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/style/images/header_bg.jpg HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/images/allmenu.gif HTTP/1.1,404,1093 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:47 +0800],GET /jyglFront/mainView/navigate/images/toggle_menu.gif HTTP/1.1,404,1105 127.0.0.1,-,-,[08/May/2014:13:42:48 +0800],GET /jygl/jaxrs/article/getArticleList/10-1 HTTP/1.1,200,20913 127.0.0.1,-,-,[08/May/2014:13:42:48 +0800],GET /jygl/jaxrs/article/getTotalArticleRecords HTTP/1.1,200,22 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:48 +0800],GET /jyglFront/baseInfo_articleList?flag=1 HTTP/1.1,200,8989 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:42:48 +0800],GET /jyglFront/mainView/studentView/style/images/nav_10.png HTTP/1.1,404,1117 127.0.0.1,-,-,[08/May/2014:13:43:21 +0800],GET /jygl/jaxrs/right/isValidUserByType/1-admin-superadmin HTTP/1.1,200,20 127.0.0.1,-,-,[08/May/2014:13:43:21 +0800],GET /jygl/jaxrs/right/getUserByLoginName/admin HTTP/1.1,200,198 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/right_login2home?loginName=admin&password=superadmin&type=1 HTTP/1.1,200,2525 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/js/tree.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/js/jquery.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/js/frame.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/style/style.css HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/menuList.jsp HTTP/1.1,200,47603 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/images/logo.png HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/images/leftmenu_bg.gif HTTP/1.1,404,1105 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/images/toggle_menu.gif HTTP/1.1,404,1105 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/style/images/header_bg.jpg HTTP/1.1,304,- 127.0.0.1,-,-,[08/May/2014:13:43:21 +0800],GET /jygl/jaxrs/article/getArticleList/10-1 HTTP/1.1,200,20913 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/navigate/images/allmenu.gif HTTP/1.1,404,1093 127.0.0.1,-,-,[08/May/2014:13:43:21 +0800],GET /jygl/jaxrs/article/getTotalArticleRecords HTTP/1.1,200,22 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/baseInfo_articleList?
flag=1 HTTP/1.1,200,8989 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:21 +0800],GET /jyglFront/mainView/studentView/style/images/nav_10.png HTTP/1.1,404,1117 127.0.0.1,-,-,[08/May/2014:13:43:25 +0800],GET /jygl/jaxrs/graduate/graduateBatchService/getGraduateBatchByConditions?
graduateBatchName=&pageSize=10&pageNo=1 HTTP/1.1,200,597 127.0.0.1,-,-,[08/May/2014:13:43:25 +0800],GET /jygl/jaxrs/graduate/graduateBatchService/getTotalGraduateBatchByCondition?
graduateBatchName= HTTP/1.1,200,21 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:26 +0800],GET /jyglFront/graduate_initGraduateBatch HTTP/1.1,200,8766 127.0.0.1,-,-,[08/May/2014:13:43:27 +0800],GET /jygl/jaxrs/exam/examParameterService/getAllStudyCenters HTTP/1.1,200,29089 127.0.0.1,-,-,[08/May/2014:13:43:27 +0800],GET /jygl/jaxrs/exam/examParameterService/getAllGradeInfo HTTP/1.1,200,3785 127.0.0.1,-,-,[08/May/2014:13:43:27 +0800],GET /jygl/jaxrs/enroll/educationLevelService/allEducationLevels HTTP/1.1,200,227 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:28 +0800],GET /jyglFront/graduate_initGraduateQulifyCheck HTTP/1.1,200,26397 127.0.0.1,-,-,[08/May/2014:13:43:29 +0800],GET /jygl/jaxrs/exam/examParameterService/getAllStudyCenters HTTP/1.1,200,29089 127.0.0.1,-,-,[08/May/2014:13:43:29 +0800],GET /jygl/jaxrs/exam/examParameterService/getAllGradeInfo HTTP/1.1,200,3785 127.0.0.1,-,-,[08/May/2014:13:43:29 +0800],GET /jygl/jaxrs/enroll/educationLevelService/allEducationLevels HTTP/1.1,200,227 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:29 +0800],GET /jyglFront/graduate_initLeaveSchoolInfo HTTP/1.1,200,20125 127.0.0.1,-,-,[08/May/2014:13:43:30 +0800],GET /jygl/jaxrs/exam/examParameterService/getAllStudyCenters HTTP/1.1,200,29089 127.0.0.1,-,-,[08/May/2014:13:43:31 +0800],GET /jygl/jaxrs/exam/examParameterService/getAllGradeInfo HTTP/1.1,200,3785 127.0.0.1,-,-,[08/May/2014:13:43:31 +0800],GET /jygl/jaxrs/enroll/educationLevelService/allEducationLevels HTTP/1.1,200,227 127.0.0.1,-,-,[08/May/2014:13:43:31 +0800],GET /jygl/jaxrs/graduate/graduateBatchService/getAllGraduateBatch HTTP/1.1,200,597 0:0:0:0:0:0:0:1,-,-,[08/May/2014:13:43:31 +0800],GET /jyglFront/graduate_initGraduateInfo HTTP/1.1,200,28464 127.0.0.1,-,-,[08/May/2014:14:27:10 +0800],GET / HTTP/1.1,200,11444 127.0.0.1,-,-,[08/May/2014:14:27:12 +0800],GET /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurrentClassPlanVO HTTP/1.1,204,- 127.0.0.1,-,-,[08/May/2014:14:27:12 +0800],GET /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurClassPlanVO HTTP/1.1,204,- 127.0.0.1,-,-,[08/May/2014:14:27:34 +0800],GET /jygl/jaxrs/exam/examArrangeService/getExamBatchIdByLatest HTTP/1.1,200,43 127.0.0.1,-,-,[08/May/2014:14:27:34 +0800],GET /jygl/jaxrs/exam/examArrangeService/getExamBatchNameByEBId/4af2a0424323412e014327739b1702bd HTTP/1.1,200,16 127.0.0.1,-,-,[08/May/2014:14:27:35 +0800],GET /jygl/jaxrs/exam/examSubscribeService/getUtilObjectThirExamBatchsByEBNN/201403 HTTP/1.1,200,653 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:35 +0800],GET /jyglFront/exam_initgroupsubscribestatistic HTTP/1.1,200,13551 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:37 +0800],GET /jyglFront/exam_initsubstudentsubscribe HTTP/1.1,500,3900 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:41 +0800],GET /jyglFront/supervisor/intoInitAssignmentDetail HTTP/1.1,200,1808 127.0.0.1,-,-,[08/May/2014:14:27:42 +0800],GET /jygl/jaxrs/right/isValidUserByType/1-admin-superadmin HTTP/1.1,200,20 127.0.0.1,-,-,[08/May/2014:14:27:42 +0800],GET /jygl/jaxrs/right/getUserByLoginName/admin HTTP/1.1,200,198 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/right_login2home?loginName=admin&password=superadmin&type=1 HTTP/1.1,200,2525 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/js/tree.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/style/style.css HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/js/frame.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/js/jquery.js HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/menuList.jsp HTTP/1.1,200,47603 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/images/leftmenu_bg.gif HTTP/1.1,404,1105 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/images/allmenu.gif HTTP/1.1,404,1093 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/images/logo.png HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/style/images/header_bg.jpg HTTP/1.1,304,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/mainView/navigate/images/toggle_menu.gif HTTP/1.1,404,1105 127.0.0.1,-,-,[08/May/2014:14:27:42 +0800],GET /jygl/jaxrs/article/getArticleList/10-1 HTTP/1.1,200,20913 127.0.0.1,-,-,[08/May/2014:14:27:42 +0800],GET /jygl/jaxrs/article/getTotalArticleRecords HTTP/1.1,200,22 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:42 +0800],GET /jyglFront/baseInfo_articleList?flag=1 HTTP/1.1,200,8989 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:43 +0800],GET /jyglFront/mainView/studentView/style/images/nav_10.png HTTP/1.1,404,1117 127.0.0.1,-,-,[08/May/2014:14:27:44 +0800],GET /jygl/jaxrs/nationInfo/getAllNationInPage?
pageSize=10&pageNo=1 HTTP/1.1,200,374 127.0.0.1,-,-,[08/May/2014:14:27:44 +0800],GET /jygl/jaxrs/nationInfo/getTotalNations HTTP/1.1,200,22 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:44 +0800],GET /jyglFront/baseInfo_nationInfoList HTTP/1.1,200,7471 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:44 +0800],GET /jyglFront/common/css/menuStyle2.css HTTP/1.1,404,1060 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:44 +0800],GET /jyglFront/common/css/basic.css HTTP/1.1,200,1476 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:45 +0800],GET /jyglFront/common/css/_images/botton2.gif HTTP/1.1,404,1075 127.0.0.1,-,-,[08/May/2014:14:27:47 +0800],GET /jygl/jaxrs/enroll/educationLevelService/allEducationLevels HTTP/1.1,200,227 127.0.0.1,-,-,[08/May/2014:14:27:47 +0800],GET /jygl/jaxrs/enroll/gradeInfoService/allGradeInfos HTTP/1.1,200,3785 127.0.0.1,-,-,[08/May/2014:14:27:47 +0800],GET /jygl/jaxrs/teaching/teachingPlanService/getSpeicalListByTwo?gradeID=&educationLevelID= HTTP/1.1,200,12061 127.0.0.1,-,-,[08/May/2014:14:27:47 +0800],GET /jygl/jaxrs/enroll/studyCenterService/allStudyCentersByUtilObject HTTP/1.1,200,6006 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:48 +0800],GET /jyglFront/teaching/openReplaceChooseCourse HTTP/1.1,200,26455 127.0.0.1,-,-,[08/May/2014:14:27:49 +0800],GET /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurClassBatchPlanVOList?
newClassBatchName=&gradeName=&term=-1 HTTP/1.1,204,- 127.0.0.1,-,-,[08/May/2014:14:27:49 +0800],GET /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurClassBatchPlanVOList?newClassBatchName=&gradeName=&term=-1 HTTP/1.1,204,- 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:49 +0800],GET /jyglFront/teaching/openChooseCourse HTTP/1.1,200,1611 127.0.0.1,-,-,[08/May/2014:14:27:51 +0800],GET /jygl/jaxrs/enroll/gradeInfoService/currentGradeInfo HTTP/1.1,200,473 127.0.0.1,-,-,[08/May/2014:14:27:51 +0800],GET /jygl/jaxrs/enroll/educationLevelService/allEducationLevels HTTP/1.1,200,227 127.0.0.1,-,-,[08/May/2014:14:27:51 +0800],GET /jygl/jaxrs/enroll/gradeInfoService/allGradeInfos HTTP/1.1,200,3785 127.0.0.1,-,-,[08/May/2014:14:27:51 +0800],GET /jygl/jaxrs/teaching/teachingPlanService/hasTeachingPlanInGrade?
gradeId=4af2a042437c2c0801437ed1cdea0017 HTTP/1.1,200,20 127.0.0.1,-,-,[08/May/2014:14:27:51 +0800],GET /jygl/jaxrs/teaching/teachingPlanService/hasTeachingPlanInGrade?gradeId=4af2a0423f41d66d013f5a1f766c00ce HTTP/1.1,200,20 127.0.0.1,-,-,[08/May/2014:14:27:51 +0800],GET /jygl/jaxrs/teaching/teachingPlanService/teachingPlanListByEducationLevelAndGradeId?
grade=4af2a042437c2c0801437ed1cdea0017&educationLevel= HTTP/1.1,200,4849 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:52 +0800],GET /jyglFront/teaching/teachingPlanList HTTP/1.1,200,22794 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:27:52 +0800],GET /jyglFront/js/jquery.form.js HTTP/1.1,200,30330 127.0.0.1,-,-,[08/May/2014:14:28:02 +0800],GET /jygl/jaxrs/exam/examArrangeService/getExamBatchIdByLatest HTTP/1.1,200,43 127.0.0.1,-,-,[08/May/2014:14:28:02 +0800],GET /jygl/jaxrs/exam/examArrangeService/getExamBatchNameByEBId/4af2a0424323412e014327739b1702bd HTTP/1.1,200,16 127.0.0.1,-,-,[08/May/2014:14:28:02 +0800],GET /jygl/jaxrs/exam/examSubscribeService/getUtilObjectThirExamBatchsByEBNN/201403 HTTP/1.1,200,653 0:0:0:0:0:0:0:1,-,-,[08/May/2014:14:28:02 +0800],GET /jyglFront/exam_initgroupsubscribestatistic HTTP/1.1,200,13551 127.0.0.1,-,-,[08/May/2014:14:28:19 +0800],POST /jygl/jaxrs/right/addUserLog HTTP/1.1,200,- 127.0.0.1,-,-,[08/May/2014:14:31:42 +0800],GET /jygl/jaxrs/exam/examSubscribeService/groupSubscribe/201403/0/0/201309/1 HTTP/1.1,200,-
2. 要解決的問題：統計資源（URL）被訪問的次數。
3. 編程實現
想法：解析Tomcat日誌，map的工作是將每一行日誌中的URL截取作為key值，value為1表示1次，reduce的工作是將同樣key值的行合並。value為總次數。
代碼例如以下：
package org.ly.ccnu;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
public class SecondTest extends Configured implements Tool{
enum Counter{
LINESKIP,
}
public static class Map extends Mapper<LongWritable,Text,Text,IntWritable>{
private static final IntWritable one = new IntWritable(1);
public void map(LongWritable key,Text value,Context context) throws IOException, InterruptedException{
String line = value.toString();
try{
String[] lineSplit = line.split(",");
String requestUrl = lineSplit[4];
requestUrl = requestUrl.substring(requestUrl.indexOf(‘ ‘)+1, requestUrl.lastIndexOf(‘ ‘));
Text out = new Text(requestUrl);
context.write(out,one);
}catch(java.lang.ArrayIndexOutOfBoundsException e){
context.getCounter(Counter.LINESKIP).increment(1);
}
}
}
public static class Reduce extends Reducer<Text,IntWritable,Text,IntWritable>{
public void reduce(Text key, Iterable<IntWritable> values,Context context)throws IOException{
int count = 0;
for(IntWritable v : values){
count = count + 1;
}
try {
context.write(key, new IntWritable(count));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
@Override
public int run(String[] args) throws Exception {
Configuration conf = getConf();
Job job = new Job(conf, "logAnalysis");
job.setJarByClass(SecondTest.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setOutputFormatClass(TextOutputFormat.class);
//keep the same format with the output of Map and Reduce
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.waitForCompletion(true);
return job.isSuccessful()?0:1;
}
public static void main(String[] args)throws Exception{
int res = ToolRunner.run(new Configuration(), new SecondTest(),args);
System.exit(res);
}
}
4. 處理結果
/ 2 /jygl/jaxrs/article/getArticleList/10-1 3 /jygl/jaxrs/article/getTotalArticleRecords 3 /jygl/jaxrs/enroll/educationLevelService/allEducationLevels 5 /jygl/jaxrs/enroll/gradeInfoService/allGradeInfos 2 /jygl/jaxrs/enroll/gradeInfoService/currentGradeInfo 1 /jygl/jaxrs/enroll/studyCenterService/allStudyCentersByUtilObject 1 /jygl/jaxrs/exam/examArrangeService/getExamBatchIdByLatest 2 /jygl/jaxrs/exam/examArrangeService/getExamBatchNameByEBId/4af2a0424323412e014327739b1702bd 2 /jygl/jaxrs/exam/examParameterService/getAllGradeInfo 3 /jygl/jaxrs/exam/examParameterService/getAllStudyCenters 3 /jygl/jaxrs/exam/examSubscribeService/getUtilObjectThirExamBatchsByEBNN/201403 2 /jygl/jaxrs/exam/examSubscribeService/groupSubscribe/201403/0/0/201309/1 1 /jygl/jaxrs/graduate/graduateBatchService/getAllGraduateBatch 1 /jygl/jaxrs/graduate/graduateBatchService/getGraduateBatchByConditions?graduateBatchName=&pageSize=10&pageNo=1 1 /jygl/jaxrs/graduate/graduateBatchService/getTotalGraduateBatchByCondition?graduateBatchName= 1 /jygl/jaxrs/nationInfo/getAllNationInPage?pageSize=10&pageNo=1 1 /jygl/jaxrs/nationInfo/getTotalNations 1 /jygl/jaxrs/right/addUserLog 1 /jygl/jaxrs/right/getUserByLoginName/admin 3 /jygl/jaxrs/right/isValidUserByType/1-admin-superadmin 3 /jygl/jaxrs/teaching/teachingPlanService/getSpeicalListByTwo?gradeID=&educationLevelID= 1 /jygl/jaxrs/teaching/teachingPlanService/hasTeachingPlanInGrade?
gradeId=4af2a0423f41d66d013f5a1f766c00ce 1 /jygl/jaxrs/teaching/teachingPlanService/hasTeachingPlanInGrade?
gradeId=4af2a042437c2c0801437ed1cdea0017 1 /jygl/jaxrs/teaching/teachingPlanService/teachingPlanListByEducationLevelAndGradeId?grade=4af2a042437c2c0801437ed1cdea0017&educationLevel= 1 /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurClassBatchPlanVOList?newClassBatchName=&gradeName=&term=-1 2 /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurClassPlanVO 2 /jygl/jaxrs/teachingManage/ClassBatchPlanService/getCurrentClassPlanVO 2 /jyglFront/baseInfo_articleList?flag=1 3 /jyglFront/baseInfo_nationInfoList 1 /jyglFront/common/css/_images/botton2.gif 1 /jyglFront/common/css/basic.css 1 /jyglFront/common/css/menuStyle2.css 1 /jyglFront/exam_initgroupsubscribestatistic 2 /jyglFront/exam_initsubstudentsubscribe 1 /jyglFront/graduate_initGraduateBatch 1 /jyglFront/graduate_initGraduateInfo 1 /jyglFront/graduate_initGraduateQulifyCheck 1 /jyglFront/graduate_initLeaveSchoolInfo 1 /jyglFront/js/jquery.form.js 1 /jyglFront/mainView/navigate/images/allmenu.gif 3 /jyglFront/mainView/navigate/images/leftmenu_bg.gif 3 /jyglFront/mainView/navigate/images/logo.png 3 /jyglFront/mainView/navigate/images/toggle_menu.gif 3 /jyglFront/mainView/navigate/js/frame.js 3 /jyglFront/mainView/navigate/js/jquery.js 3 /jyglFront/mainView/navigate/js/tree.js 3 /jyglFront/mainView/navigate/menuList.jsp 3 /jyglFront/mainView/navigate/style/images/header_bg.jpg 3 /jyglFront/mainView/navigate/style/style.css 3 /jyglFront/mainView/studentView/style/images/nav_10.png 3 /jyglFront/right_login2home?
loginName=admin&password=superadmin&type=1 3 /jyglFront/supervisor/intoInitAssignmentDetail 1 /jyglFront/teaching/openChooseCourse 1 /jyglFront/teaching/openReplaceChooseCourse 1 /jyglFront/teaching/teachingPlanList 1
Hadoop學習：Map/Reduce初探與小Demo實現