倒排索引案例（多Job串联）
需求
需求分析
第一次处理
OneIndexMapper
public class OneIndexMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
String name;
@Override
protected void setup(Context context) throws IOException, InterruptedException {
// 获取文件名称
FileSplit inputSplit = (FileSplit) context.getInputSplit();
name = inputSplit.getPath().getName();
}
Text k = new Text();
IntWritable v = new IntWritable(1);
@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
// 1 获取一行
String line = value.toString();
// 2 切割
String[] fields = line.split(" ");
// 3 写出
for (String word : fields) {
k.set(word + "--" + name);
context.write(k, v);
}
}
}
OneIndexReducer
public class OneIndexReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
@Override
protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
// 1 累加求和
int sum = 0;
for (IntWritable value : values) {
sum += value.get();
}
IntWritable v = new IntWritable();
v.set(sum);
// 2 写出
context.write(key, v);
}
}
OneIndexDriver
public class OneIndexDriver {
public static void main(String[] args) throws Exception {
args = new String[]{"e:/input/inputoneindex", "e:/output5"};
Configuration configuration = new Configuration();
Job job = Job.getInstance(configuration);
job.setJarByClass(OneIndexDriver.class);
job.setMapperClass(OneIndexMapper.class);
job.setReducerClass(OneIndexReducer.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
boolean result = job.waitForCompletion(true);
System.exit(result ? 0 : 1);
}
}
第二次处理
TwoIndexMapper
public class TwoIndexMapper extends Mapper<LongWritable, Text, Text, Text> {
Text k = new Text();
Text v = new Text();
@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
// 1 获取一行
String line = value.toString();
// 2 切割
String[] fields = line.split("--");
// 3 封装
k.set(fields[0]);
v.set(fields[1]);
// 4 写出
context.write(k, v);
}
}
TwoIndexReducer
public class TwoIndexReducer extends Reducer<Text, Text, Text, Text> {
Text v = new Text();
@Override
protected void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
// 1 拼接字符串
StringBuffer sb = new StringBuffer();
for (Text value : values) {
sb.append(value.toString().replace("\t", "-->") + "\t");
}
v.set(sb.toString());
// 2 写出
context.write(key, v);
}
}
TwoIndexDriver
public class TwoIndexDriver {
public static void main(String[] args) throws Exception {
args = new String[]{"e:/input/inputtwoindex", "e:/output6"};
Configuration configuration = new Configuration();
Job job = Job.getInstance(configuration);
job.setJarByClass(TwoIndexDriver.class);
job.setMapperClass(TwoIndexMapper.class);
job.setReducerClass(TwoIndexReducer.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(Text.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
boolean result = job.waitForCompletion(true);
System.exit(result ? 0 : 1);
}
}
