小编hao*_*hao的帖子

这是我的源代码

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableComparable;
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.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;

public class PageRank {

public static final String MAGIC_STRING = ">>>>";
boolean overwrite = true;

PageRank(boolean overwrite){
    this.overwrite = overwrite;
}
public static class TextPair implements WritableComparable<TextPair>{
    Text x;
    int ordering;

    public TextPair(){
        x = new Text();
        ordering = 1;
    } …

让我们说字符串是<title>xyz</title> 我想从字符串中提取xyz出来的.我用了:

Pattern titlePattern = Pattern.compile("&lttitle&gt\\s*(.+?)\\s*&lt/title&gt");
Matcher titleMatcher = titlePattern.matcher(line);
String title=titleMatcher.group(1));    

但是我收到了titlePattern.matcher(line)的错误;