一、建立工程
使用Gradle建立一个普通的Java工程。当然如果你习惯使用Maven,你也可以用Maven。
二、更换镜像 添加依赖
repositories {
maven { url 'https://maven.aliyun.com/repository/apache-snapshots' }
maven { url 'https://maven.aliyun.com/repository/central' }
maven { url 'https://maven.aliyun.com/repository/google' }
maven { url 'https://maven.aliyun.com/repository/gradle-plugin' }
maven { url 'https://maven.aliyun.com/repository/jcenter' }
maven { url "https://maven.aliyun.com/repository/spring" }
maven { url "https://maven.aliyun.com/repository/spring-plugin" }
maven { url "https://maven.aliyun.com/repository/public" }
mavenCentral()
}
dependencies {
testCompile group: 'junit', name: 'junit', version: '4.12'
compile group: 'org.apache.hadoop', name: 'hadoop-common', version: '3.2.0'
compile group: 'org.apache.hadoop', name: 'hadoop-mapreduce-client-common', version: '3.2.0'
}
三、编写代码
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
public class Read {
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://192.168.75.100:9000");
FileSystem fs = FileSystem.get(conf);
FSDataInputStream fis = fs.open(new Path("/input/g.txt"));
IOUtils.copyBytes(fis,System.out,4096,true);
}
}
- 其中192.168.75.100是master的IP地址;
- g.txt 是hdfs下input文件夹中的一个文件 ;
- IOUtils是Hadoop提供的IO工具类。