根据手机流量数据，编写 MapReduce 程序来统计出每个手机号码的一年总流量。

Mapper阶段：
输入：每行数据包括手机号码、日期、上行流量、下行流量，以制表符分隔。
输出：键为手机号码，值为一年内的总流量，以制表符分隔。

public class MyMapper extends Mapper<LongWritable, Text, Text, LongWritable> {
    private Text phoneNum = new Text();
    private LongWritable totalFlow = new LongWritable();

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String[] words = value.toString().split("\t");
        String phoneNumStr = words[0];
        long upFlow = Long.parseLong(words[2]);
        long downFlow = Long.parseLong(words[3]);
        phoneNum.set(phoneNumStr);
        totalFlow.set(upFlow + downFlow);
        context.write(phoneNum, totalFlow);
    }
}

Reducer阶段：
输入：每个手机号码的流量总和，以键值对的形式传递。
输出：每个手机号码的一年总流量，以制表符分隔。

public class MyReducer extends Reducer<Text, LongWritable, Text, LongWritable> {
    private LongWritable totalFlow = new LongWritable();

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