给大家 一个建议 如果使用1.XX的版本hadoop ?建议大家严格按照 ?以下的 ?第一条 中的博文的版本安装，可以是单机或者伪分布式，主要是因为，hadoop版本和 eclipse插件版本如果不一致会带来很多问题，解决起来比较麻烦，
先说明一下 ?此次搭建 hadoop ?运行示例 ，过程中参考的文章：
1. eclipse 搭建 hadoop环境：
http://www.cnblogs.com/xia520pi/archive/2012/05/20/2510723.html
2.运行hadoop是遇到的问题：
? 第一个问题：XX.XX.XXX.WordCount$TokenizerMapper ? 这个主要是因为 插件版本不一致的问题，但是目前我没有解决，我用的还是1.2.1的 有源码 ，查了一些资料 也手工打了一个 ?eclipse-plugin 但是最终还是不好使，打eclipse-plugins 的 可以参考 ?利用hadoop源码 打plugins的文章（我打了包但是还是不好用），绕过这个问题的方法可以参考 （http://www.cnblogs.com/spork/archive/2010/04/21/1717592.html ?文章有几篇 写的不错，可以都看看也算都hadoop执行过程的一个了解） ，这个最终解决办法是模拟了 hadoop将本地文件打成jar 的过程
? 以上问题解决 按照网上的文章应该是已经可以运行了 ，但是我这又遇到了 其他问题：
问题二：
eclipse 中运行 org.apache.hadoop.mapreduce.lib.input.InvalidInputException
? ? 执行 ?wordount 的时候，配置input文件找不到：明明就在那里防止相对路径绝对路径都试过了 还是不行，最后想着 hadoop在命令行执行 的话，是 将本地文件上传到 ?hadoop中的，但是我运行时候每次都报的的是本地文件找不到，所以应该写远程文件地址，参开 执行成功的hadoop文件发现文件地址为：
mapred.output.dirhdfs://172.16.236.11:9000/user/libin/output/wordcount-ec
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所以就修改了本地代码程序：
FileInputFormat.addInputPath(job, new Path("hdfs://172.16.236.11:9000" + File.separator + otherArgs[0])); FileOutputFormat.setOutputPath(job, new Path( "hdfs://172.16.236.11:9000" + File.separator + otherArgs[1]));?
这样 本地执行的代码就可以 在hadoop服务端执行了。
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这里还有一个问题 就是，如果每次测试都需要将本地文件上传到 hadoop服务端 ，好像有点麻烦，所以 可以考虑，每次addInputPath 的时候，在这个之前，先执行以下 类型 hadoop fs ?-put 的 代码，将本地文件上传到 ?hadoop服务端，这样就不用每次手工上传文件到 服务器 参考?
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http://younglibin.iteye.com/admin/blogs/1925109
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贴一个完整的 示例程序吧：
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package com.younglibin.hadoop.test;import java.io.File;import java.io.IOException;import java.util.StringTokenizer;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapred.JobConf;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.util.GenericOptionsParser;import com.younglibin.hadoop.EJob;public class WordCount { public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> { private final static IntWritable one = new IntWritable(1); private Text word = new Text(); public void map(Object key, Text value, Context context) throws IOException, InterruptedException { StringTokenizer itr = new StringTokenizer(value.toString()); while (itr.hasMoreTokens()) { word.set(itr.nextToken()); context.write(word, one); } } } public static class IntSumReducer extends Reducer<Text, IntWritable, Text, IntWritable> { private IntWritable result = new IntWritable(); public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { int sum = 0; for (IntWritable val : values) { sum += val.get(); } result.set(sum); context.write(key, result); } } public static void main(String[] args) throws Exception { File jarFile = EJob.createTempJar("bin"); EJob.addClasspath("/home/libin/software/hadoop/hadoop-1.2.1/conf"); ClassLoader classLoader = EJob.getClassLoader(); Thread.currentThread().setContextClassLoader(classLoader); Configuration conf = new Configuration(); conf.set("mapred.job.tracker", "172.16.236.11:9001"); args = new String[] { "/user/libin/input/libin", "/user/libin/output/wordcount-ec" }; String[] otherArgs = new GenericOptionsParser(conf, args) .getRemainingArgs(); if (otherArgs.length != 2) { System.err.println("Usage: wordcount <in> <out>"); System.exit(2); } Job job = new Job(conf, "word count"); job.setJarByClass(WordCount.class); ((JobConf) job.getConfiguration()).setJar(jarFile.toString()); job.setMapperClass(TokenizerMapper.class); job.setCombinerClass(IntSumReducer.class); job.setReducerClass(IntSumReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); FileInputFormat.addInputPath(job, new Path("hdfs://172.16.236.11:9000" + File.separator + otherArgs[0])); FileOutputFormat.setOutputPath(job, new Path( "hdfs://172.16.236.11:9000" + File.separator + otherArgs[1])); System.exit(job.waitForCompletion(true) ? 0 : 1); }}
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/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package com.younglibin.hadoop;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.lang.reflect.Array;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.net.URL;import java.net.URLClassLoader;import java.util.ArrayList;import java.util.Arrays;import java.util.Enumeration;import java.util.jar.JarEntry;import java.util.jar.JarFile;import java.util.jar.JarOutputStream;import java.util.jar.Manifest;public class EJob { private static ArrayList<URL> classPath = new ArrayList<URL>(); /** Unpack a jar file into a directory. */ public static void unJar(File jarFile, File toDir) throws IOException { JarFile jar = new JarFile(jarFile); try { Enumeration entries = jar.entries(); while (entries.hasMoreElements()) { JarEntry entry = (JarEntry) entries.nextElement(); if (!entry.isDirectory()) { InputStream in = jar.getInputStream(entry); try { File file = new File(toDir, entry.getName()); if (!file.getParentFile().mkdirs()) { if (!file.getParentFile().isDirectory()) { throw new IOException("Mkdirs failed to create " + file.getParentFile().toString()); } } OutputStream out = new FileOutputStream(file); try { byte[] buffer = new byte[8192]; int i; while ((i = in.read(buffer)) != -1) { out.write(buffer, 0, i); } } finally { out.close(); } } finally { in.close(); } } } } finally { jar.close(); } } /** * Run a Hadoop job jar. If the main class is not in the jar's manifest, then * it must be provided on the command line. */ public static void runJar(String[] args) throws Throwable { String usage = "jarFile [mainClass] args..."; if (args.length < 1) { System.err.println(usage); System.exit(-1); } int firstArg = 0; String fileName = args[firstArg++]; File file = new File(fileName); String mainClassName = null; JarFile jarFile; try { jarFile = new JarFile(fileName); } catch (IOException io) { throw new IOException("Error opening job jar: " + fileName).initCause(io); } Manifest manifest = jarFile.getManifest(); if (manifest != null) { mainClassName = manifest.getMainAttributes().getValue("Main-Class"); } jarFile.close(); if (mainClassName == null) { if (args.length < 2) { System.err.println(usage); System.exit(-1); } mainClassName = args[firstArg++]; } mainClassName = mainClassName.replaceAll("/", "."); File tmpDir = new File(System.getProperty("java.io.tmpdir")); tmpDir.mkdirs(); if (!tmpDir.isDirectory()) { System.err.println("Mkdirs failed to create " + tmpDir); System.exit(-1); } final File workDir = File.createTempFile("hadoop-unjar", "", tmpDir); workDir.delete(); workDir.mkdirs(); if (!workDir.isDirectory()) { System.err.println("Mkdirs failed to create " + workDir); System.exit(-1); } Runtime.getRuntime().addShutdownHook(new Thread() { public void run() { try { fullyDelete(workDir); } catch (IOException e) { } } }); unJar(file, workDir); classPath.add(new File(workDir + "/").toURL()); classPath.add(file.toURL()); classPath.add(new File(workDir, "classes/").toURL()); File[] libs = new File(workDir, "lib").listFiles(); if (libs != null) { for (int i = 0; i < libs.length; i++) { classPath.add(libs[i].toURL()); } } ClassLoader loader = new URLClassLoader(classPath.toArray(new URL[0])); Thread.currentThread().setContextClassLoader(loader); Class<?> mainClass = Class.forName(mainClassName, true, loader); Method main = mainClass.getMethod("main", new Class[] { Array.newInstance( String.class, 0).getClass() }); String[] newArgs = Arrays.asList(args).subList(firstArg, args.length) .toArray(new String[0]); try { main.invoke(null, new Object[] { newArgs }); } catch (InvocationTargetException e) { throw e.getTargetException(); } } /** * Delete a directory and all its contents. If we return false, the directory * may be partially-deleted. */ public static boolean fullyDelete(File dir) throws IOException { File contents[] = dir.listFiles(); if (contents != null) { for (int i = 0; i < contents.length; i++) { if (contents[i].isFile()) { if (!contents[i].delete()) { return false; } } else { // try deleting the directory // this might be a symlink boolean b = false; b = contents[i].delete(); if (b) { // this was indeed a symlink or an empty directory continue; } // if not an empty directory or symlink let // fullydelete handle it. if (!fullyDelete(contents[i])) { return false; } } } } return dir.delete(); } /** * Add a directory or file to classpath. * * @param component */ public static void addClasspath(String component) { if ((component != null) && (component.length() > 0)) { try { File f = new File(component); if (f.exists()) { URL key = f.getCanonicalFile().toURL(); if (!classPath.contains(key)) { classPath.add(key); } } } catch (IOException e) { } } } /** * Add default classpath listed in bin/hadoop bash. * * @param hadoopHome */ public static void addDefaultClasspath(String hadoopHome) { // Classpath initially contains conf dir. addClasspath(hadoopHome + "/conf"); // For developers, add Hadoop classes to classpath. addClasspath(hadoopHome + "/build/classes"); if (new File(hadoopHome + "/build/webapps").exists()) { addClasspath(hadoopHome + "/build"); } addClasspath(hadoopHome + "/build/test/classes"); addClasspath(hadoopHome + "/build/tools"); // For releases, add core hadoop jar & webapps to classpath. if (new File(hadoopHome + "/webapps").exists()) { addClasspath(hadoopHome); } addJarsInDir(hadoopHome); addJarsInDir(hadoopHome + "/build"); // Add libs to classpath. addJarsInDir(hadoopHome + "/lib"); addJarsInDir(hadoopHome + "/lib/jsp-2.1"); addJarsInDir(hadoopHome + "/build/ivy/lib/Hadoop/common"); } /** * Add all jars in directory to classpath, sub-directory is excluded. * * @param dirPath */ public static void addJarsInDir(String dirPath) { File dir = new File(dirPath); if (!dir.exists()) { return; } File[] files = dir.listFiles(); if (files == null) { return; } for (int i = 0; i < files.length; i++) { if (files[i].isDirectory()) { continue; } else { addClasspath(files[i].getAbsolutePath()); } } } /** * Create a temp jar file in "java.io.tmpdir". * * @param root * @return * @throws IOException */ public static File createTempJar(String root) throws IOException { if (!new File(root).exists()) { return null; } Manifest manifest = new Manifest(); manifest.getMainAttributes().putValue("Manifest-Version", "1.0"); final File jarFile = File.createTempFile("EJob-", ".jar", new File(System .getProperty("java.io.tmpdir"))); Runtime.getRuntime().addShutdownHook(new Thread() { public void run() { jarFile.delete(); } }); JarOutputStream out = new JarOutputStream(new FileOutputStream(jarFile), manifest); createTempJarInner(out, new File(root), ""); out.flush(); out.close(); return jarFile; } private static void createTempJarInner(JarOutputStream out, File f, String base) throws IOException { if (f.isDirectory()) { File[] fl = f.listFiles(); if (base.length() > 0) { base = base + "/"; } for (int i = 0; i < fl.length; i++) { createTempJarInner(out, fl[i], base + fl[i].getName()); } } else { out.putNextEntry(new JarEntry(base)); FileInputStream in = new FileInputStream(f); byte[] buffer = new byte[1024]; int n = in.read(buffer); while (n != -1) { out.write(buffer, 0, n); n = in.read(buffer); } in.close(); } } /** * Return a classloader based on user-specified classpath and parent * classloader. * * @return */ public static ClassLoader getClassLoader() { ClassLoader parent = Thread.currentThread().getContextClassLoader(); if (parent == null) { parent = EJob.class.getClassLoader(); } if (parent == null) { parent = ClassLoader.getSystemClassLoader(); } return new URLClassLoader(classPath.toArray(new URL[0]), parent); }}
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