【Hadoop】HDFS客户端开发示例

1、原理、步骤

2、HDFS客户端示例代码

package com.ares.hadoop.hdfs;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URISyntaxException;

import org.apache.commons.io.IOUtils;
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.LocatedFileStatus;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.RemoteIterator;
import org.apache.log4j.Logger;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class HDFSTest {
    private static final Logger LOGGER = Logger.getLogger(HDFSTest.class);
    
    private FileSystem fs = null;
    
    @Before
    public void setUp() throws IOException, URISyntaxException, InterruptedException {
        Configuration conf = new Configuration();
//        conf.set("fs.defaultFS", "hdfs://HADOOP-NODE1:9000");
//        URI uri = new URI("hdfs://HADOOP-NODE1:9000");
//        this.fs = FileSystem.get(uri, conf, "HADOOP");
        this.fs = FileSystem.get(conf);
    }
    @After
    public void tearDown() throws IOException {
        // TODO Auto-generated method stub
        this.fs.close();
    }
    
    @Test
    public void testGET() throws IOException {
        // TODO Auto-generated method stub 
        LOGGER.debug("HDFSTest: GET FILE TEST");
        Path path = new Path("hdfs://HADOOP-NODE1:9000/jdk-7u60-linux-x64.tar.gz");
        FSDataInputStream fsDataInputStream = this.fs.open(path);
        FileOutputStream fileOutputStream = new FileOutputStream("./testdata/get-test-jdk.tar.gz");
        IOUtils.copy(fsDataInputStream, fileOutputStream);
    }
    
    @Test
    public void testPUT() throws IOException {
        // TODO Auto-generated method stub 
        LOGGER.debug("HDFSTest: PUT FILE TEST");
        Path path = new Path("hdfs://HADOOP-NODE1:9000/put-test-jdk.tar.gz");
        FSDataOutputStream fsDataOutputStream = this.fs.create(path);
        FileInputStream fileInputStream = new FileInputStream("./testdata/test-jdk.tar.gz");
        IOUtils.copy(fileInputStream, fsDataOutputStream);
    }
    
    @Test
    public void testGET_NEW() throws IOException {
        // TODO Auto-generated method stub 
        LOGGER.debug("HDFSTest: GET_NEW FILE TEST");
        Path src = new Path("hdfs://HADOOP-NODE1:9000/jdk-7u60-linux-x64.tar.gz");
        Path dst = new Path("./testdata/get-test-new-jdk.tar.gz");
        this.fs.copyToLocalFile(src, dst);
    }
    
    @Test
    public void testPUT_NEW() throws IOException {
        // TODO Auto-generated method stub 
        LOGGER.debug("HDFSTest: PUT_NEW FILE TEST");
        Path src = new Path("./testdata/test-jdk.tar.gz");
        Path dst = new Path("hdfs://HADOOP-NODE1:9000/put-test-new-jdk.tar.gz");
        this.fs.copyFromLocalFile(src , dst);
    }
    
    @Test
    public void testMKDIR() throws IOException {
        // TODO Auto-generated method stub 
        LOGGER.debug("HDFSTest: MKDIR TEST");
        Path f = new Path("/mkdir-test/testa/testb");
        this.fs.mkdirs(f);
    }
    
    @Test
    public void testRM() throws IOException {
        // TODO Auto-generated method stub 
        LOGGER.debug("HDFSTest: RM TEST");
        Path f = new Path("/mkdir-test");
        this.fs.delete(f, true);
    }
    
    @Test
    public void testLIST() throws IOException {
        // TODO Auto-generated method stub 
        LOGGER.debug("HDFSTest: LIST TEST");
        Path f = new Path("/");
        //LIST FILES
        RemoteIterator<LocatedFileStatus> files = this.fs.listFiles(f, true);
        while (files.hasNext()) {
            LocatedFileStatus file = files.next();
            LOGGER.debug(file.getPath());
            LOGGER.debug(file.getPath().getName());
        }
        
        //LIST DIRS
        FileStatus[] files2 = this.fs.listStatus(f);
//        for (int i = 0; i < files2.length; i++) {
//            LOGGER.debug(files2[i].getPath().getName());
//        }
        for (FileStatus fileStatus : files2) {
            LOGGER.debug(fileStatus.getPath().getName());
            LOGGER.debug(fileStatus.isDirectory());
        }
    }
}