Hadoop实习实现访问次数排序2023
时间: 2024-05-03 15:19:38 浏览: 20
好的,你需要跟着以下步骤来实现Hadoop实习实现访问次数排序:
1. 首先,需要将数据集准备好,数据集应该是一个文本文件,每一行都包含一个IP地址和对应的访问次数,使用制表符分隔。例如:
```
192.168.1.1 100
192.168.1.2 200
192.168.1.3 50
...
```
2. 接下来,需要编写Mapper类和Reducer类。Mapper类的任务是将每一行的数据划分为键值对,其中键是IP地址,值是对应的访问次数。Reducer类的任务是统计每个IP地址的总访问次数,并将其作为键值对输出。代码实现如下:
Mapper类:
```java
public class AccessMapper extends Mapper<LongWritable, Text, Text, LongWritable> {
private Text ip = new Text();
private LongWritable count = new LongWritable();
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
String line = value.toString();
String[] fields = line.split("\t");
ip.set(fields[0]);
count.set(Long.parseLong(fields[1]));
context.write(ip, count);
}
}
```
Reducer类:
```java
public class AccessReducer extends Reducer<Text, LongWritable, Text, LongWritable> {
private LongWritable result = new LongWritable();
public void reduce(Text key, Iterable<LongWritable> values, Context context) throws IOException, InterruptedException {
long sum = 0;
for (LongWritable value : values) {
sum += value.get();
}
result.set(sum);
context.write(key, result);
}
}
```
3. 接下来,需要编写一个Job类来将Mapper和Reducer类组合在一起,并设置一些必要的参数,例如输入路径、输出路径、输入格式、输出格式、Mapper类的输出键值对类型、Reducer类的输出键值对类型等。代码实现如下:
```java
public class AccessCount {
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = Job.getInstance(conf, "access count");
job.setJarByClass(AccessCount.class);
job.setMapperClass(AccessMapper.class);
job.setReducerClass(AccessReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(LongWritable.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
```
4. 最后,在命令行中输入以下命令来启动Hadoop作业:
```
$ hadoop jar access.jar AccessCount /input/path /output/path
```
其中,access.jar是你编译后的jar包,/input/path是数据集的输入路径,/output/path是输出路径。作业完成后,你可以在输出路径中找到排序后的结果。
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