hadoop2.6.0的eclipse插件编译和设置

1.编译hadoop2.6.0的eclipse插件


下载源码：
git clone https://github.com/winghc/hadoop2x-eclipse-plugin.git


编译源码：
cd src/contrib/eclipse-plugin  
ant jar -Dversion=2.6.0 -Declipse.home=/opt/eclipse -Dhadoop.home=/opt/hadoop-2.6.0   
eclipse.home 和 hadoop.home 设置成你自己的环境路径


命令行执行编译，产生了8个警告信息，直接忽略。
compile:
     [echo] contrib: eclipse-plugin
    [javac] /software/hadoop2x-eclipse-plugin/src/contrib/eclipse-plugin/build.xml:76: warning: ‘includeantruntime‘ was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
    [javac] Compiling 45 source files to /software/hadoop2x-eclipse-plugin/build/contrib/eclipse-plugin/classes
    [javac] /opt/hadoop-2.6.0/share/hadoop/common/hadoop-common-2.6.0.jar(org/apache/hadoop/fs/Path.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘: class file for org.apache.hadoop.classification.InterfaceAudience not found
    [javac] /opt/hadoop-2.6.0/share/hadoop/hdfs/hadoop-hdfs-2.6.0.jar(org/apache/hadoop/hdfs/DistributedFileSystem.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘
    [javac] /opt/hadoop-2.6.0/share/hadoop/common/hadoop-common-2.6.0.jar(org/apache/hadoop/fs/FileSystem.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘
    [javac] /opt/hadoop-2.6.0/share/hadoop/common/hadoop-common-2.6.0.jar(org/apache/hadoop/fs/FileSystem.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘
    [javac] /opt/hadoop-2.6.0/share/hadoop/common/hadoop-common-2.6.0.jar(org/apache/hadoop/fs/FileSystem.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘
    [javac] /opt/hadoop-2.6.0/share/hadoop/common/hadoop-common-2.6.0.jar(org/apache/hadoop/fs/FileSystem.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘
    [javac] /opt/hadoop-2.6.0/share/hadoop/common/hadoop-common-2.6.0.jar(org/apache/hadoop/fs/FSDataInputStream.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘
    [javac] /opt/hadoop-2.6.0/share/hadoop/common/hadoop-common-2.6.0.jar(org/apache/hadoop/fs/FSDataOutputStream.class): warning: Cannot find annotation method ‘value()‘ in type ‘LimitedPrivate‘
    [javac] Note: Some input files use or override a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
    [javac] 8 warnings


生成位置：

 [jar] Building jar: /software/hadoop2x-eclipse-plugin/build/contrib/eclipse-plugin/hadoop-eclipse-plugin-2.6.0.jar

2.安装插件


登录桌面后面要打开eclipse的用户最好是hadoop的管理员，也就是hadoop安装时所配置用户，否则会出现拒绝读写权限问题。


复制编译好的jar到eclipse插件目录，重启eclipse
配置 hadoop 安装目录
window ->preference -> hadoop Map/Reduce -> Hadoop installation directory
配置Map/Reduce 视图
window ->Open Perspective -> other->Map/Reduce -> 点击“OK”
windows → show view → other->Map/Reduce Locations-> 点击“OK”
控制台会多出一个“Map/Reduce Locations”的Tab页
在“Map/Reduce Locations” Tab页 点击图标<大象+>或者在空白的地方右键，选择“New Hadoop location…”，弹出对话框“New hadoop location…”，配置如下内容：


注意：MR Master和DFS Master配置必须和mapred-site.xml和core-site.xml等配置文件一致
打开Project Explorer,查看HDFS文件系统。

3.新建Map/Reduce任务

File->New->project->Map/Reduce Project->Next
编写WordCount类：

package mytest;
 
import java.io.IOException;
import java.util.*;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.util.*;
 
public class WordCount {
         public static class Map extends MapReduceBase implements
                            Mapper<LongWritable, Text, Text, IntWritable> {
                   private final static IntWritable one = new IntWritable(1);
                   private Text word = new Text();
 
                   public void map(LongWritable key, Text value,
                                     OutputCollector<Text, IntWritable> output, Reporter reporter)
                                     throws IOException {
                            String line = value.toString();
                            StringTokenizer tokenizer = new StringTokenizer(line);
                            while (tokenizer.hasMoreTokens()) {
                                     word.set(tokenizer.nextToken());
                                     output.collect(word, one);
                            }
                   }
         }
 
         public static class Reduce extends MapReduceBase implements
                            Reducer<Text, IntWritable, Text, IntWritable> {
                   public void reduce(Text key, Iterator<IntWritable> values,
                                     OutputCollector<Text, IntWritable> output, Reporter reporter)
                                     throws IOException {
                            int sum = 0;
                            while (values.hasNext()) {
                                     sum += values.next().get();
                            }
                            output.collect(key, new IntWritable(sum));
                   }
         }
 
         public static void main(String[] args) throws Exception {
                   JobConf conf = new JobConf(WordCount.class);
                   conf.setJobName("wordcount");
 
                   conf.setOutputKeyClass(Text.class);
                   conf.setOutputValueClass(IntWritable.class);
 
                   conf.setMapperClass(Map.class);
                   conf.setReducerClass(Reduce.class);
 
                   conf.setInputFormat(TextInputFormat.class);
                   conf.setOutputFormat(TextOutputFormat.class);
 
                   FileInputFormat.setInputPaths(conf, new Path(args[0]));
                   FileOutputFormat.setOutputPath(conf, new Path(args[1]));
 
                   JobClient.runJob(conf);
         }
}


配置运行时参数:右键-->Run as-->Run Confiugrations


in是hdfs的文件夹（自己创建），里面放要处理的文件。out存放输出结果
将程序放在hadoop集群上运行：右键-->Runas -->Run on Hadoop,最终的输出结果会在HDFS相应的文件夹下显示。至此，Linux下hadoop-2.6.0 eclipse插件配置完成。


配置过程中出先的问题：
在eclipse中无法向文件HDFS文件系统写入的问题，这将直接导致eclipse下编写的程序不能在hadoop上运行。
打开conf/hdfs-site.xml，找到dfs.permissions属性修改为false（默认为true）OK了。
        <property>
            <name>dfs.permissions</name>
            <value>false</value>
        </property>
    改完需要重启HDFS；
最简单的就是刚才说的登录桌面启动eclipse的用户本身就是hadoop的管理员