Hadoop在Windows下用IDEA调试

工作环境：Windows10

Hadoop版本：hadoop-2.6.4

开发工具：IDEA

测试代码为Hadoop权威指南书上的代码具体不细说，直接贴代码：

MaxTemperatureMapper.java

public class MaxTemperatureMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
    private static final int MISSING = 9999;

    @Override
    public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String line = value.toString();
        String year = line.substring(15, 19);
        int airTemperature;
        if (line.charAt(87) == '+') { // parseInt doesn't like leading plus signs
            airTemperature = Integer.parseInt(line.substring(88, 92));
        } else {
            airTemperature = Integer.parseInt(line.substring(87, 92));
        }
        String quality = line.substring(92, 93);
        if (airTemperature != MISSING && quality.matches("[01459]")) {
            context.write(new Text(year), new IntWritable(airTemperature));
        }
    }
}

MaxTemperatureReduce.java

public class MaxTemperatureReducer
        extends Reducer<Text, IntWritable, Text, IntWritable> {
    @Override
    public void reduce(Text key, Iterable<IntWritable> values,
                       Context context)
            throws IOException, InterruptedException {
        int maxValue = Integer.MIN_VALUE;
        for (IntWritable value : values) {
            maxValue = Math.max(maxValue, value.get());
        }
        context.write(key, new IntWritable(maxValue));
    }
}

MaxTemperature.java

public class MaxTemperature {
    public static void main(String[] args) throws Exception {

        if(args.length != 2){
            System.err.println("Usage: MaxTemperature <input path> <output path>");
            System.exit(-1);
        }

        Job job = Job.getInstance();
        job.setJarByClass(MaxTemperature.class);

        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        job.setMapperClass(MaxTemperatureMapper.class);
        job.setReducerClass(MaxTemperatureReducer.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}

1、下载hadoop-2.6.4到windows环境下

2、配置path

HADOOP_HOME D:\installApp\Apache\apache-hadoop-2.6.4

path 添加上%HADOOP_HOME%\bin

3、hadoop_dll2.6.0下的文件拷贝到hadoop/bin下，详见附件，可能需要重启电脑

4、core-site.xml文件放入你的resources文件夹下面作为资源文件

5、把测试的1901.gz和1902.gz文件放入一个input文件夹中

6、设置好你的args两个参数输入路径input 输出路径output，然后运行就OK啦！

7、可能会遇到报错java.lang.UnsatisfiedLinkError: org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z

下载hadoop源文件，拷贝并修改NativeIO.class

不想下载源码的同学可以下载附件中的该文件

放入特定路径中org.apache.hadoop.io.nativeio 用于覆盖源文件

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Hadoop在Windows下用IDEA调试

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