六：熟悉HDFS基本常用命令（一）
Hadoop命令学习-官网链接：
http://hadoop.apache.org/docs/r2.6.4/hadoop-project-dist/hadoop-common/FileSystemShell.html
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一. 创建HDFS文件：
public class Test4CreateFile {
/**
* 创建HDFS文件：
* */
public static void main(String[] args) {
try {
Configuration conf = new Configuration();
URI uri = new URI("hdfs://192.168.226.129:9000");
byte[] buff = "Hello Hadoop HDFS".getBytes();
FileSystem fs = FileSystem.get(uri, conf);
Path dfs = new Path("hdfs://192.168.226.129:9000/studyhadoop");
FSDataOutputStream outputStream = fs.create(dfs);
outputStream.write(buff,0,buff.length);
FileStatus files[] = fs.listStatus( dfs );
for( FileStatus file:files){
System.out.println( "file: " + file.getPath() );
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
二：删除HDFS文件
public class Test5DeleteFile {
/**
* 删除HDFS文件：
* */
public static void main(String[] args) {
try {
Configuration conf = new Configuration();
URI uri = new URI("hdfs://192.168.226.129:9000");
FileSystem fs = FileSystem.get(uri, conf);
Path delef = new Path("hdfs://192.168.226.129:9000/testhadoop1");
boolean isDeleted = fs.delete(delef, false);
System.out.println( "isDelete: " + isDeleted );
} catch (Exception e) {
e.printStackTrace();
}
}
}
三：创建HDFS目录
public class Test9Mkdir {
/**
* HDFS下 创建目录文件
* */
public static void main(String[] args) {
try {
Configuration conf = new Configuration();
URI uri = new URI("hdfs://192.168.226.129:9000");
FileSystem fs = FileSystem.get(uri, conf);
Path dfs = new Path("hdfs://192.168.226.129:9000/testhadoop");
boolean isMkdirs = fs.mkdirs(dfs);
if( isMkdirs ){
System.out.println( " Make Dir Successful ! ");
}else{
System.out.println( " Make Dir Failure ! ");
}
fs.close();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (URISyntaxException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
四：重命名HDFS文件
public class Test2Rename {
/**
* 重命名HDFS文件：
* */
public static void main(String[] args) {
try {
Configuration conf = new Configuration();
URI uri = new URI("hdfs://192.168.226.129:9000");
FileSystem fs = FileSystem.get(uri,conf);
Path oldpath = new Path("hdfs://192.168.226.129:9000/testhadoop");
Path newpath = new Path("hdfs://192.168.226.129:9000/testhadoop1");
//判断该文件是否存在
boolean isExists = fs.exists(oldpath);
System.out.println( "isExists: " +isExists );
//重命名文件
fs.rename(oldpath, newpath);
isExists = fs.exists(newpath);
System.out.println( "newpathisExists: " +isExists );
} catch (Exception e) {
e.printStackTrace();
}
}
}
五：上传本地文件至HDFS
public class Test3CopyFile {
/**
* 上传本地文件到HDFS
* */
public static void main(String[] args) {
try {
Configuration conf = new Configuration();
URI uri = new URI("hdfs://192.168.226.129:9000");
FileSystem fs = FileSystem.get(uri, conf);
Path src = new Path("F:\\04-HadoopStudy\\mapreduce.txt");
Path dst = new Path("hdfs://192.168.226.129:9000/rootdir");
fs.copyFromLocalFile(src, dst);
System.out.println("Upload " + conf.get("fs.default.name"));
FileStatus files[] = fs.listStatus( dst );
for( FileStatus file:files){
System.out.println( file.getPath() );
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
六. 从HDFS下载文件至本地
public class Test10CopyToFile {
/**
* 从HDFS下载文件至本地
* */
public static void main(String[] args) {
try {
Configuration conf = new Configuration();
URI uri = new URI("hdfs://192.168.226.129:9000");
FileSystem fs = FileSystem.get(uri, conf);
Path src = new Path("F:\\");
Path dst = new Path("hdfs://192.168.226.129:9000/studyhadoop");
fs.copyToLocalFile(dst, src);
System.out.println("DownLoad " + conf.get("fs.default.name"));
FileStatus files[] = fs.listStatus( dst );
for( FileStatus file:files){
System.out.println( file.getPath() );
}
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (URISyntaxException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}