根据网站每日访问次数的统计需求，分析Map阶段和Reduce阶段的处理逻辑，编写Mapper模块、Reducer模块和Driver模块的代码。定义一个dailyAccessCount类，封装Mapper模块、Reducer模块和Driver模块的实现

在Hadoop MapReduce框架下，我们首先需要了解Map阶段和Reduce阶段的任务。Map阶段负责将原始数据分割成小块并应用用户提供的Mapper函数，这个阶段主要是键值对的生成。而Reduce阶段则是对Map阶段产生的中间结果进行汇总，通常按键进行聚合操作。

对于`dailyAccessCount`类，我们可以按照以下结构编写：

import org.apache.hadoop.conf.Configuration;
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.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

public class DailyAccessCount {

    // Mapper 类，这里假设输入是一行URL，输出是键（日期）和值（访问次数）
    public static class URLToDayCountMapper extends Mapper<Object, Text, Text, IntWritable> {
        private final static IntWritable one = new IntWritable(1);
        private Text dateKey = new Text();

        @Override
        protected void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            String[] parts = value.toString().split(",");
            dateKey.set(parts[0]); // 假设日期在URL的第一个部分
            context.write(dateKey, one);
        }
    }

    // Reducer 类，接收所有相同的日期，并累加访问次数
    public static class SumReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
        private IntWritable result = new IntWritable();

        @Override
        protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable val : values) {
                sum += val.get();
            }
            result.set(sum);
            context.write(key, result);
        }
    }

    // Driver 模块，配置Job并运行
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf, "Daily Access Count");
        job.setJarByClass(DailyAccessCount.class); // 设置主类

        job.setMapperClass(URLToDayCountMapper.class);
        job.setCombinerClass(SumReducer.class); // 如果数据量较小可以考虑启用 combiner
        job.setReducerClass(SumReducer.class);

        FileInputFormat.addInputPath(job, new Path(args[0])); // 输入文件路径
        FileOutputFormat.setOutputPath(job, new Path(args[1])); // 输出文件路径

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