背景:在上篇文章中按照大神“扎心了老铁”的博客,在服务器上搭建了hadoop的伪分布式环境。大神的博客上是使用eclipse来调试,但是我入门以来一直用的是idea,eclipse已经不习惯,于是便摸索着配置了idea远程调试hadoop的环境。
步骤一:
下载与服务器上的hadoop同版本的hadoop安装包,我下载的是hadoop-2.7.7.tar.gz,下载后解压到某个目录,比如D:Softwarehadoop-2.7.7,不需要其他配置和安装
步骤二:
下载hadooop.dll和winutils.exe,这两个文件主要是调试运行的时候要用,不然运行会报错。我是在网上下载的2.7.x版本的压缩包。解压后放置在D:Softwarehadoop-2.7.7/bin/文件夹下:
同时将hadoop.dll文件复制到C:WindowsSystem32下,并且重启电脑,否则会报错
Exception in thread "main"java.lang.UnsatisfiedLinkError:org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z
步骤三:
配置系统环境变量:
配置环境变量Path,在现有Path后追加 %HADOOP_HOME%in;%HADOOP_HOME%sbin;
步骤四:
在idea中新建一个maven项目,配置pom.xml依赖
<dependencies> <!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-client --> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-client</artifactId> <version>2.7.7</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>2.7.7</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-hdfs</artifactId> <version>2.7.7</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-mapreduce-client-core</artifactId> <version>2.7.7</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-mapreduce-client-jobclient</artifactId> <version>2.7.7</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-mapreduce-client-common</artifactId> <version>2.7.7</version> </dependency> </dependencies>
步骤五:将服务器上集群中hadoop/etc/hadoop/下的core-site.xml和hdfs-site.xml和log4j.properties配置复制到idea项目下的resources路径下
注意1:core-site.xml中的fs.defaultFS的值的ip不可用localhost,否则服务器不暴露ip,从PC本地上无法连上hadoop服务;ip在服务器和本地同步修改,服务器端修改后需重启hadoop服务
步骤六:代码测试
测试1-网上的hdfs读写的例子up2hdfs.java,直接运行即可
import org.apache.commons.lang.StringUtils; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IOUtils; import java.io.*; import java.net.URI; public class up2hdfs { private static String HDFSUri = "hdfs://10.164.96.220:9000"; /** * 1、获取文件系统 * * @retrun FileSystem 文件系统 */ public static FileSystem getFileSystem(){ //读取配置文件 Configuration conf = new Configuration(); //文件系统 FileSystem fs = null; String hdfsUri = HDFSUri; if (StringUtils.isBlank(hdfsUri)){ //返回默认文件系统,如果在hadoop集群下运行,使用此种方法可直接获取默认文件系统; try{ fs = FileSystem.get(conf); }catch(IOException e){ e.printStackTrace(); } }else{ //返回指定的文件系统,如果在本地测试,需要此种方法获取文件系统; try{ URI uri = new URI(hdfsUri.trim()); fs = FileSystem.get(uri,conf); } catch (Exception e) { e.printStackTrace(); } } return fs ; } /** * 2、创建文件目录 * @param path 文件路径 */ public static void mkdir(String path){ try { FileSystem fs = getFileSystem(); System.out.println("FilePath"+path); //创建目录 fs.mkdirs(new Path(path)); //释放资源 fs.close(); } catch (IOException e) { e.printStackTrace(); } } /** * 3、判断目录是否存在 * * @param filePath 目录路径 * @param create 若不存在是否创建 * */ public static boolean existDir(String filePath,boolean create){ boolean flag = false; if (StringUtils.isNotEmpty(filePath)){ return flag; } try{ Path path = new Path(filePath); //FileSystem对象 FileSystem fs = getFileSystem(); if (create){ if (!fs.exists(path)){ fs.mkdirs(path); } } if (fs.isDirectory(path)){ flag = true; } }catch (Exception e){ e.printStackTrace(); } return flag; } /** * 4、本地文件上传至HDFS * * @param srcFile 源文件路径 * @param destPath 目的文件路径 */ public static void copyFileToHDFS(String srcFile,String destPath) throws Exception{ FileInputStream fis = new FileInputStream(new File(srcFile));//读取本地文件 Configuration config = new Configuration(); FileSystem fs = FileSystem.get(URI.create(HDFSUri+destPath),config); OutputStream os = fs.create(new Path(destPath)); //cpoy IOUtils.copyBytes(fis,os,4096,true); System.out.println("copy 完成 ......"); fs.close(); } /** * 5、从HDFS下载文件到本地 * * @param srcFile 源文件路径 * @param destPath 目的文件路径 * */ public static void getFile(String srcFile,String destPath)throws Exception{ //HDFS文件地址 String file = HDFSUri+srcFile; Configuration config = new Configuration(); //构建filesystem FileSystem fs = FileSystem.get(URI.create(file),config); //读取文件 InputStream is = fs.open(new Path(file)); IOUtils.copyBytes(is,new FileOutputStream(new File(destPath)),2048,true); System.out.println("下载完成......"); fs.close(); } /** * 6、删除文件或者文件目录 * * @param path */ public static void rmdir(String path){ try { //返回FileSystem对象 FileSystem fs = getFileSystem(); String hdfsUri = HDFSUri; if (StringUtils.isNotBlank(hdfsUri)){ path = hdfsUri+path; } System.out.println("path"+path); //删除文件或者文件目录 delete(Path f)此方法已经弃用 System.out.println(fs.delete(new Path(path),true)); fs.close(); } catch (Exception e) { e.printStackTrace(); } } /** * 7、读取文件的内容 * * @param filePath * @throws IOException */ public static void readFile(String filePath)throws IOException{ Configuration config = new Configuration(); String file = HDFSUri+filePath; FileSystem fs = FileSystem.get(URI.create(file),config); //读取文件 InputStream is =fs.open(new Path(file)); //读取文件 IOUtils.copyBytes(is, System.out, 2048, false); //复制到标准输出流 fs.close(); } /** * 主方法测试 */ public static void main(String[] args) throws Exception {//200 //连接fs FileSystem fs = getFileSystem(); System.out.println(fs.getUsed()); //创建路径 mkdir("/dit2"); //验证是否存在 System.out.println(existDir("/dit2",false)); //上传文件到HDFS copyFileToHDFS("G:\testFile\HDFSTest.txt","/dit/HDFSTest.txt"); //下载文件到本地 getFile("/dit/HDFSTest.txt","G:\HDFSTest.txt"); // getFile(HDFSFile,localFile); //删除文件 rmdir("/dit2"); //读取文件 readFile("/dit/HDFSTest.txt"); } }
测试2-网上的mapreduce的例子
import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Mapper; import java.io.IOException; import java.util.StringTokenizer; public class WcMapper extends Mapper<LongWritable,Text,Text,IntWritable>{ @Override protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { // IntWritable one=new IntWritable(1); String line=value.toString(); StringTokenizer st=new StringTokenizer(line); //StringTokenizer "kongge" while (st.hasMoreTokens()){ String word= st.nextToken(); context.write(new Text(word),new IntWritable(1)); //output } } }
import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Reducer; import java.io.IOException; /** * Created by iespark on 2/26/16. */ public class McReducer extends Reducer<Text,IntWritable,Text,IntWritable> { @Override protected void reduce(Text key, Iterable<IntWritable> iterable, Context context) throws IOException, InterruptedException { int sum=0; for (IntWritable i:iterable){ sum=sum+i.get(); } context.write(key,new IntWritable(sum)); } }
import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; 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; /** * Created by iespark on 2/26/16. */ public class JobRun { public static void main(String[] args){ System.setProperty("hadoop.home.dir", "D:\Software\hadoop-2.7.7"); Configuration conf=new Configuration(); try{ Job job = Job.getInstance(conf, "word count"); // Configuration conf, String jobName; job.setJarByClass(JobRun.class); job.setMapperClass(WcMapper.class); job.setReducerClass(McReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); //解决No job jar file set. User classes may not be found. See Job or Job#setJar(String)报错的问题 // job.setJar("E:\idea2017workspace\myhadoop\out\artifacts\myhadoop_jar\myhadoop.jar"); FileInputFormat.addInputPath(job,new Path(args[0])); FileSystem fs= FileSystem.get(conf); Path op1=new Path(args[1]); if(fs.exists(op1)){ fs.delete(op1, true); System.out.println("存在此输出路径,已删除!!!"); } FileOutputFormat.setOutputPath(job,op1); System.exit(job.waitForCompletion(true)?0:1); }catch (Exception e){ e.printStackTrace(); } } }
JobRun.java运行时需要输入参数,hdfs计算输入和输出的路径,或者在run configurations中配置,如下图,注意路径的hdfs地址需要为core-site.xml中的地址