如何从nutch获取html内容

Question

在抓取网页时,有没有办法在nutch中获取每个网页的html内容？

Answer 1

是的,您可以实际导出已爬网段的内容.这不是直截了当的,但对我来说效果很好.首先,使用以下代码创建一个java项目:

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.nutch.protocol.Content;
import org.apache.nutch.util.NutchConfiguration;

import java.io.File;
import java.io.FileOutputStream;

public class NutchSegmentOutputParser {

public static void main(String[] args) {

    if (args.length != 2) {
        System.out.println("usage: segmentdir (-local | -dfs <namenode:port>) outputdir");
        return;
    }

    try {
        Configuration conf = NutchConfiguration.create();
        FileSystem fs = FileSystem.get(conf);


        String segment = args[0];

        File outDir = new File(args[1]);
        if (!outDir.exists()) {
            if (outDir.mkdir()) {
                System.out.println("Creating output dir " + outDir.getAbsolutePath());
            }
        }

        Path file = new Path(segment, Content.DIR_NAME + "/part-00000/data");
        SequenceFile.Reader reader = new SequenceFile.Reader(fs, file, conf);


        Text key = new Text();
        Content content = new Content();

        while (reader.next(key, content)) {
            String filename = key.toString().replaceFirst("http://", "").replaceAll("/", "___").trim();

            File f = new File(outDir.getCanonicalPath() + "/" + filename);
            FileOutputStream fos = new FileOutputStream(f);
            fos.write(content.getContent());
            fos.close();
            System.out.println(f.getAbsolutePath());
        }
        reader.close();
        fs.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

}

我推荐使用Maven; 添加以下依赖项:

     <dependency>
      <groupId>org.apache.nutch</groupId>
        <artifactId>nutch</artifactId>
        <version>1.5.1</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-common</artifactId>
        <version>0.23.1</version>
    </dependency>

并创建一个jar包(即NutchSegmentOutputParser.jar)

您需要在您的计算机上安装Hadoop.然后运行:

$/hadoop-dir/bin/hadoop --config \
NutchSegmentOutputParser.jar:~/.m2/repository/org/apache/nutch/nutch/1.5.1/nutch-1.5.1.jar \
NutchSegmentOutputParser nutch-crawled-dir/2012xxxxxxxxx/ outdir

其中nutch-crawled-dir/2012xxxxxxxxx /是您要从中提取内容的已爬网目录(它包含'segment'子目录),outdir是输出目录.输出文件名是从URI生成的,但是斜杠替换为" _ ".

希望能帮助到你.

Answer 2

是的，有办法。查看cache.jsp 以了解它如何显示缓存的数据。