MapReduce的另一实例，给天气预报数据规范格式并且输出2

在我的上一篇博客中，我是将一个天气数据处理为了一个json格式的数据
具体的博客内容如下
https://blog.youkuaiyun.com/qq_45683188/article/details/108415084
那我们想一想，能不能就是我们再把json格式的数据转化为普通类型的数据，听起来还是比较让人感到这样是不是有病啊，为什么不用原来的数据，偏要转过来又转过去，对于开发而言，这样做确实有病，但是对于我们这些正在学习的海洋里学习的小白来说，更能掌握一个新的知识，好了废话少说，上正菜了
对于这个将json格式转化为普通的字符串的数据来说，用的依赖肯定不是json_lib的依赖了

  <dependency>
         <groupId>commons-beanutils</groupId>
         <artifactId>commons-beanutils</artifactId>
         <version>1.9.3</version>
     </dependency>
     <dependency>
         <groupId>commons-collections</groupId>
         <artifactId>commons-collections</artifactId>
         <version>3.2.1</version>
     </dependency>
     <dependency>
         <groupId>commons-lang</groupId>
         <artifactId>commons-lang</artifactId>
         <version>2.6</version>
     </dependency>
     <dependency>
         <groupId>commons-logging</groupId>
         <artifactId>commons-logging</artifactId>
         <version>1.1.1</version>
     </dependency>
     <dependency>
         <groupId>net.sf.ezmorph</groupId>
         <artifactId>ezmorph</artifactId>
         <version>1.0.6</version>
     </dependency>
     <dependency>
         <groupId>net.sf.json-lib</groupId>
         <artifactId>json-lib</artifactId>
         <version>2.4</version>
         <classifier>jdk15</classifier>
     </dependency>’

以上是需要新加的依赖
关于这个json的一个大致用法，大家可以参照
https://www.cnblogs.com/sunzn/archive/2013/02/12/2910241.html
这个网址
我就是将json格式的内容转化为javabean格式的代码，然后重写javabean中的toString‘方法
现在上代码

import net.sf.json.JSONObject;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class ReverseMap extends Mapper<LongWritable, Text,Text, NullWritable> {
    Text k=new Text ();

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String line=value.toString ();
        JSONObject json=JSONObject.fromObject (line);
        //将字符串转化为JavaBean
        Weather weather=(Weather) JSONObject.toBean (json,Weather.class);
        k.set (weather.toString ());
        context.write (k,NullWritable.get ());

    }
}

首先就是我的mapper阶段的代码
然后就是我的javabean这个类的代码

public class Weather {
    private String date;
    private String temp;
    private  String city;
    private String wind;
    public Weather(){

    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getTemp() {
        return temp;
    }

    public void setTemp(String temp) {
        this.temp = temp;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getWind() {
        return wind;
    }

    public void setWind(String wind) {
        this.wind = wind;
    }

    @Override
    public String toString() {
        return this.date+","+this.temp+","+this.city+","+this.wind+",";
    }
}

其中就是重写的toString的方法
剩下的就是我的reduce阶段的代码，和driver阶段的代码了

import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class ReversReduce extends Reducer<Text, NullWritable,Text,NullWritable> {

    @Override
    protected void reduce(Text key, Iterable<NullWritable> values, Context context) throws IOException, InterruptedException {
        context.write (key,NullWritable.get ());
    }
}

以上是reduce阶段的代码

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
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;

import java.io.IOException;


public class WeatherDriver {
    public static void main(String[] args) {
        args=new String[2];
        args[0]="D:\\LIB\\weather.txt";
        args[1]="D:\\LIB\\output";
        Configuration configuration=new Configuration ();
        try {
            Job job=Job.getInstance (configuration);
            job.setJarByClass (WeatherDriver.class);
            job.setMapperClass (ReverseMap.class);
            job.setReducerClass (ReversReduce.class);
            job.setMapOutputKeyClass (Text.class);
            job.setMapOutputValueClass (NullWritable.class);
            job.setOutputKeyClass (Text.class);
            job.setOutputValueClass (NullWritable.class);

            Path path = new Path(args[1]);
            FileSystem fileSystem = path.getFileSystem(configuration);
            if (fileSystem.exists(path)) {
                fileSystem.delete(path, true);
            }
            FileInputFormat.setInputPaths (job,new Path (args[0]));
            FileOutputFormat.setOutputPath (job,new Path (args[1]));
            boolean a=job.waitForCompletion (true);
            System.out.println (a );
        } catch (IOException e) {
            e.printStackTrace ( );
        } catch (InterruptedException e) {
            e.printStackTrace ( );
        } catch (ClassNotFoundException e) {
            e.printStackTrace ( );
        }
    }
}

以上为driver阶段的代码
最后就是说说你写这个程序，需要注意什么，这里其实也没有太多可以说的，对于我个人而言，我最想讲的就是，一定要注意你的导包问题，导错包找错方法真的很难受啊