hadoop2.7创建maven实例，hadoop2.7maven实例

hadoop2.7创建maven实例，hadoop2.7maven实例

1.安装maven与eclipse配置

2.创建一个简单的maven项目

3.pom设置，添加dependencies

 <dependencies>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-hdfs</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-core</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-jobclient</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-common</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>jdk.tools</groupId>
            <artifactId>jdk.tools</artifactId>
            <version>1.7</version>
            <scope>system</scope>
            <systemPath>${JAVA_HOME}/lib/tools.jar</systemPath>
        </dependency>
    </dependencies>

4.把hadoop的core-site.xml,hdfs-site.xml,mapred-site.xml拷贝到resource文件夹下

5.编写程序

这个程序可以直接运行。

package first;

import java.io.IOException;
import java.net.URI;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.mapred.JobConf;

public class HdfsDAO {

    //HDFS访问地址
    private static final String HDFS = "hdfs://192.168.109.200:9000/";

    public HdfsDAO(Configuration conf) {
        this(HDFS, conf);
    }

    public HdfsDAO(String hdfs, Configuration conf) {
        this.hdfsPath = hdfs;
        this.conf = conf;
    }

    //hdfs路径
    private String hdfsPath;
    //Hadoop系统配置
    private Configuration conf;

    //启动函数
    public static void main(String[] args) throws IOException {
        JobConf conf = config();
        HdfsDAO hdfs = new HdfsDAO(conf);
//        hdfs.mkdirs("/tmp/new/two");
//        hdfs.ls("/tmp/new");
        hdfs.createFile("/tmp/new/text.log", "Hello world!!");
        hdfs.cat("/tmp/new/text.log");
        
    }        
    
    //加载Hadoop配置文件
    public static JobConf config(){
//    	return (JobConf) new Configuration();  
        JobConf conf = new JobConf(HdfsDAO.class);
        conf.setJobName("HdfsDAO");
        conf.addResource("classpath:/hadoop/core-site.xml");
        conf.addResource("classpath:/hadoop/hdfs-site.xml");
        conf.addResource("classpath:/hadoop/mapred-site.xml");
        return conf;
    }
    
    public void ls(String folder) throws IOException {
        Path path = new Path(folder);
        FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);
        FileStatus[] list = fs.listStatus(path);
        System.out.println("ls: " + folder);
        System.out.println("==========================================================");
        for (FileStatus f : list) {
            System.out.printf("name: %s, folder: %s, size: %d\n", f.getPath(), f.isFile(), f.getLen());
        }
        System.out.println("==========================================================");
        fs.close();
    }
    
    public void mkdirs(String folder) throws IOException {
        Path path = new Path(folder);
        FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);
        if (!fs.exists(path)) {
            fs.mkdirs(path);
            System.out.println("Create: " + folder);
        }
        fs.close();
    }
    
    //删除文件
    public void rmr(String folder) throws IOException {
        Path path = new Path(folder);
        FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);
        fs.deleteOnExit(path);
        System.out.println("Delete: " + folder);
        fs.close();
    }
    
    public void copyFile(String local, String remote) throws IOException {
        FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);
        fs.copyFromLocalFile(new Path(local), new Path(remote));
        System.out.println("copy from: " + local + " to " + remote);
        fs.close();
    }
    
    public void cat(String remoteFile) throws IOException {
        Path path = new Path(remoteFile);
        FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);
        FSDataInputStream fsdis = null;
        System.out.println("cat: " + remoteFile);
        try {  
        	if(!fs.exists(path))
        		return;
       		fsdis =fs.open(path);
            IOUtils.copyBytes(fsdis, System.out, 4096, false);  
          } finally {  
            IOUtils.closeStream(fsdis);
            fs.close();
          }
    }
    
    public void createFile(String file, String content) throws IOException {
        Path path = new Path(file);
        FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);
        byte[] buff = content.getBytes();
//        FSDataOutputStream os = null;
        FSDataOutputStream os = null;
        
        try {
        	if(!fs.exists(path))
        		fs.createNewFile(path);
            os = fs.create(path);
            os.write(buff, 0, buff.length);
            System.out.println("Create: " + file);
        } finally {
            if (os != null)
                os.close();
        }
        fs.close();
    }
    
}