使用Java Api 操作HDFS

Z时代
2024-01-10
分类：综合

java

如题我就是一个标题党就是使用JavaApi操作HDFS，使用的是MAVEN，操作的环境是Linux

首先要配置好Maven环境，我使用的是已经有的仓库，如果你下载的jar包速度慢，可以改变Maven 下载jar包的镜像站改为阿里云。

贴一下 pom.xml

使用到的jar包

<dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>
        <!-- hadoop Client -->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>${hadoop.version}</version>
        </dependency>
</dependencies>

然后就是操作HDFS的代码

package com.zuoyan.hadoop.hdfs;
import java.io.File;
import java.io.FileInputStream;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
/**
 * use java api operate hdfs
 * 
 * @author beifeng
 * 
 */
public class HdfsApp {
    // get FileSystem
    public static FileSystem getFileSystem() throws Exception {
        Configuration conf = new Configuration();
        FileSystem fileSystem = FileSystem.get(conf);
        return fileSystem;
    }
    public static void read(String fileName) throws Exception {
        FileSystem fileSystem = getFileSystem();
        // read Path
        Path readPath = new Path(fileName);
        FSDataInputStream inStream = fileSystem.open(readPath);
        try {
            IOUtils.copyBytes(inStream, System.out, 4096, false);
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        } finally {
            // if Exception close Stream
            IOUtils.closeStream(inStream);
        }
    }
    public static void main(String[] args) throws Exception{
            //String fileName = "/user/beifeng/mapreduce/wordcount/input/wc.input";
            //read(fileName);
            FileSystem fileSystem = getFileSystem();
            //write path
            String putFileName = "/user/beifeng/put-wc.input";
            Path writePath = new Path(putFileName);
            FSDataOutputStream outputStream = fileSystem.create(writePath);
            FileInputStream inputStream = new FileInputStream(
                    new File("/opt/modules/hadoop-2.5.0/wc.input"));
            try {
                IOUtils.copyBytes(inputStream, outputStream, 4096,false);
            } catch (Exception e) {
                // TODO: handle exception
                inputStream.close();
                outputStream.close();
            }
    }
}