Hadoop快速入门——第二章、分布式集群
引包：
<dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-client</artifactId> <version>2.7.3</version> </dependency>
可以先安装一下【Big Data Tools】
安装完成后需要重新启动一下。
个人建议，先改一下【镜像】位置为国内的，我就没改，直接update了，玩了好几把【连连看】都没下载完毕。
创建测试类：
import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; public class Action { public static void main(String[] args) { Action action = new Action(); action.init(); System.out.println(action.conf); System.out.println(action.fs); } Configuration conf = null; FileSystem fs = null; public void init() { conf = new Configuration(); try { fs = FileSystem.get(conf); } catch (Exception e) { e.printStackTrace(); } } }
输出：
Configuration: core-default.xml, core-site.xml, mapred-default.xml, mapred-site.xml, yarn-default.xml, yarn-site.xml, hdfs-default.xml, hdfs-site.xml
org.apache.hadoop.fs.LocalFileSystem@43195e57
文件操作：
mkdirs:创建文件夹
import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; public class Action { public static void main(String[] args) { Action action = new Action(); action.init(); try { boolean isf = action.fs.mkdirs(new Path("/data/infos/")); System.out.println(isf?"创建成功":"创建失败"); } catch (IOException e) { e.printStackTrace(); } } Configuration conf = null; FileSystem fs = null; public void init() { conf = new Configuration(); try { fs = FileSystem.get(conf); } catch (Exception e) { e.printStackTrace(); } } }
会创建在【C盘的根目录】
copyFromLocalFile：复制文件到服务器(本地模拟)
import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; public class Action { public static void main(String[] args) { Action action = new Action(); action.init(); try { action.fs.copyFromLocalFile(new Path("D:/info.txt"),new Path("/data/infos")); } catch (IOException e) { e.printStackTrace(); } } Configuration conf = null; FileSystem fs = null; public void init() { conf = new Configuration(); try { fs = FileSystem.get(conf); } catch (Exception e) { e.printStackTrace(); } } }
本地效果：
修改文件名称【rename】:
import java.io.IOException; import java.text.SimpleDateFormat; import java.util.Date; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; public class Action { public static void main(String[] args) { Action action = new Action(); action.init(); try { SimpleDateFormat format=new SimpleDateFormat("yyyy_MM_dd"); Date now = new Date(); boolean isf = action.fs.rename(new Path("/data/infos/info.txt"), new Path("/data/infos/" + format.format(now) + ".txt")); System.out.println(isf?"修改成功":"修改失败"); } catch (IOException e) { e.printStackTrace(); } } Configuration conf = null; FileSystem fs = null; public void init() { conf = new Configuration(); try { fs = FileSystem.get(conf); } catch (Exception e) { e.printStackTrace(); } } }
本地效果：
删除文件deleteOnExit:
import java.io.IOException; import java.text.SimpleDateFormat; import java.util.Date; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; public class Action { public static void main(String[] args) { Action action = new Action(); action.init(); try { boolean isf = action.fs.deleteOnExit(new Path("/data/infos/2022_04_19.txt")); System.out.println(isf?"刪除成功":"刪除失败"); } catch (IOException e) { e.printStackTrace(); } } Configuration conf = null; FileSystem fs = null; public void init() { conf = new Configuration(); try { fs = FileSystem.get(conf); } catch (Exception e) { e.printStackTrace(); } } }
