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我正在讀取JSON文件並從JSON輸入中提取元素的MapReduce（僅限Map任務）。輸入數據：JSON映射器類中的錯誤
{"type":"cloud_monitor","format":"default","version":"1.0","id":"71101cb85441995d11a43bb","start":"1413585245.921","cp":"254623","message":{"proto":"http","protoVer":"1.1","status":"403","cliIP":"23.79.231.14","reqPort":"80","reqHost":"ksd.metareactor.com","reqMethod":"GET","reqPath":"%2findex.php","reqQuery":"path%3d57%26product_id%3d49%26route%3d%255Cwinnt%255Cwin.ini%2500.","respCT":"text/html","respLen":"286","bytes":"286","UA":"mozilla-saturn","fwdHost":"origin-demo2-akamaized.scoe-sil.net"},"reqHdr":{"accEnc":"gzip,%20deflate","cookie":"PHPSESSID%3dkkqoodvfe0rt9l7lbvqghk6e15%3bcurrency%3dUSD%3blanguage%3den"}}
我已經聲明爲JSON字符串數組變量：消息& reqHdr，你可以看到他們在context.write（）方法
地圖類：
public class JsonMapper extends Mapper<LongWritable, Text, Text, Text> {
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
String type;
String format;
String version;
String id;
String start;
String cp;
// variables for message and reqHdr
String[] line = value.toString().split("\\n");
if (line.length > 0) {
for(int i=0; i<line.length; i++) {
try {
JSONObject jsonobj = new JSONObject(line[i]);
type = (String) jsonobj.get("type");
format = (String) jsonobj.get("format");
version = (String) jsonobj.get("version");
id = (String) jsonobj.get("id");
start = (String) jsonobj.get("start");
cp = (String) jsonobj.get("cp");
// Message Variable array
JSONArray messageArray = (JSONArray) jsonobj.get("message");
for(int j=0; j<messageArray.length(); j++) {
JSONObject jsonmessageobject = messageArray.getJSONObject(j);
proto = jsonmessageobject.getString("proto");
protoVer = jsonmessageobject.getString("protoVer");
cliIP = jsonmessageobject.getString("cliIP");
reqPort = jsonmessageobject.getString("reqPort");
reqHost = jsonmessageobject.getString("reqHost");
reqMethod = jsonmessageobject.getString("reqMethod");
reqPath = jsonmessageobject.getString("reqPath");
reqQuery = jsonmessageobject.getString("reqQuery");
reqCT = jsonmessageobject.getString("reqCT");
reqLen = jsonmessageobject.getString("reqLen");
sslVer = jsonmessageobject.getString("sslVer");
status = jsonmessageobject.getString("status");
redirURL = jsonmessageobject.getString("redirURL");
respCT = jsonmessageobject.getString("respCT");
respLen = jsonmessageobject.getString("respLen");
bytes = jsonmessageobject.getString("bytes");
UA = jsonmessageobject.getString("UA");
fwdHost = jsonmessageobject.getString("fwdHost");
}
// reqHdr variable array
JSONArray reqHdrArray = (JSONArray) jsonobj.get("reqHdr");
for(int k=0; k<reqHdrArray.length(); k++) {
JSONObject jsonreqHdrobject = reqHdrArray.getJSONObject(i);
accEnc = jsonreqHdrobject.getString("accEnc");
accLang = jsonreqHdrobject.getString("accLang");
auth = jsonreqHdrobject.getString("auth");
reqHdr_cacheCtl = jsonreqHdrobject.getString("cacheCtl");
reqHdr_conn = jsonreqHdrobject.getString("conn");
reqHdr_contMD5 = jsonreqHdrobject.getString("contMD5");
cookie = jsonreqHdrobject.getString("cookie");
DNT = jsonreqHdrobject.getString("DNT");
expect = jsonreqHdrobject.getString("expect");
ifMatch = jsonreqHdrobject.getString("ifMatch");
ifMod = jsonreqHdrobject.getString("ifMod");
ifNone = jsonreqHdrobject.getString("ifNone");
ifRange = jsonreqHdrobject.getString("ifRange");
ifUnmod = jsonreqHdrobject.getString("ifUnmod");
range = jsonreqHdrobject.getString("range");
referer = jsonreqHdrobject.getString("referer");
te = jsonreqHdrobject.getString("te");
upgrade = jsonreqHdrobject.getString("upgrade");
reqHdr_via = jsonreqHdrobject.getString("via");
xFrwdFor = jsonreqHdrobject.getString("xFrwdFor");
xReqWith = jsonreqHdrobject.getString("xReqWith");
}
context.write(new Text("cloud_monitor"), new Text(type + format + version + id + start + cp + proto + protoVer + cliIP + reqPort +
reqHost + reqMethod + reqPath + reqQuery + reqCT + reqLen + sslVer + status + redirURL + respCT + respLen + bytes + UA + fwdHost + accEnc + accLang + auth +
reqHdr_cacheCtl + reqHdr_conn + reqHdr_contMD5 + cookie + DNT + expect + ifMatch + ifMod + ifNone + ifRange + ifUnmod + range + referer + te +
upgrade + reqHdr_via + xFrwdFor + xReqWith));
} catch (JSONException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
}
我收到以下錯誤消息：
Error: java.lang.ClassNotFoundException: org.json.JSONException
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.Class.forName(Class.java:270)
at org.apache.hadoop.conf.Configuration.getClassByNameOrNull(Configuration.java:2138)
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2103)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2197)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:196)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:745)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:164)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1693)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
任何人都可以告訴我我f我正在正確地執行JSON解析，特別是JSON數組（消息，reqHdr）部分或我如何修復該錯誤？
你有一個'ClassNotFoundException'這意味着你必須依賴的問題，你的代碼嘗試運行，但無法找到這個類。你有幾個選項，通常在hadoop中你應該創建一個將所有依賴編譯成一個jar的胖jar。你需要這樣的東西：https://www.mkyong.com/maven/create-a-fat-jar-file-maven-assembly-plugin/ –
@BinaryNerd我明白你在說什麼，但我的項目只有一個罐子與Json和我有關：https://mvnrepository.com/artifact/org.json/json 這些包：org.json.JSONArray; org.json.JSONException; org.json.JSONObject;在java程序中需要的引用不會導致任何版本不匹配。我不明白當我從下載的Jar獲得所有選項時，創建一個Fat jar需要什麼。 – Sidhartha
你有一個運行時錯誤，該jar在編譯時在你的環境中可用，因此你的導入工作等等。當你嘗試在你的集羣上運行你的代碼時，問題是你的代碼如何訪問JSON庫你正在使用。如果jar不在類路徑中，那麼你不會得到'ClassNotFoundException'。編譯你的依賴到你的最終jar是一種解決這個問題的方法。 –