HDFS api操作

import java.net.URI;
import java.util.Iterator;
import java.util.Map.Entry;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.BlockLocation;
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.junit.Before;
import org.junit.Test;
/**
*
* 客户端去操作hdfs时，是有一个用户身份的
* 默认情况下，hdfs客户端api会从jvm中获取一个参数来作为自己的用户身份：-DHADOOP_USER_NAME=hadoop
*
* 也可以在构造客户端fs对象时，通过参数传递进去
* @author
*
*/
public class HdfsClientDemo {
FileSystem fs = null;
Configuration conf = null;
@Before
public void init() throws Exception{

conf = new Configuration();
// conf.set("fs.defaultFS", "hdfs://mini1:9000");
conf.set("dfs.replication", "5");

//拿到一个文件系统操作的客户端实例对象
fs = FileSystem.get(conf);
//可以直接传入 uri和用户身份
fs = FileSystem.get(new URI("hdfs://mini1:9000"),conf,"hadoop");
}

/**
* 上传文件
* @throws Exception
*/
@Test
public void testUpload() throws Exception {

fs.copyFromLocalFile(new Path("c:/access.log"), new Path("/access.log.copy"));
fs.close();
}

/**
* 下载文件
* @throws Exception
*/
@Test
public void testDownload() throws Exception {

fs.copyToLocalFile(new Path("/access.log.copy"), new Path("d:/"));
}

/**
* 打印参数
*/
@Test
public void testConf(){

Iterator<Entry<String, String>> it = conf.iterator();
while(it.hasNext()){
Entry<String, String> ent = it.next();
System.out.println(ent.getKey() + " : " + ent.getValue());

}

@Test
public void testMkdir() throws Exception {
boolean mkdirs = fs.mkdirs(new Path("/testmkdir/aaa/bbb"));
System.out.println(mkdirs);

}

@Test
public void testDelete() throws Exception {

boolean flag = fs.delete(new Path("/testmkdir/aaa"), true);
System.out.println(flag);

}

/**
* 递归列出指定目录下所有子文件夹中的文件
* @throws Exception
*/
@Test
public void testLs() throws Exception {

RemoteIterator<LocatedFileStatus> listFiles = fs.listFiles(new Path("/"), true);

while(listFiles.hasNext()){
LocatedFileStatus fileStatus = listFiles.next();
System.out.println("blocksize: " +fileStatus.getBlockSize());
System.out.println("owner: " +fileStatus.getOwner());
System.out.println("Replication: " +fileStatus.getReplication());
System.out.println("Permission: " +fileStatus.getPermission());
System.out.println("Name: " +fileStatus.getPath().getName());
System.out.println("------------------");
BlockLocation[] blockLocations = fileStatus.getBlockLocations();
for(BlockLocation b:blockLocations){
System.out.println("块起始偏移量: " +b.getOffset());
System.out.println("块长度:" + b.getLength());
//块所在的datanode节点
String[] datanodes = b.getHosts();
for(String dn:datanodes){
System.out.println("datanode:" + dn);
}
}

}

@Test
public void testLs2() throws Exception {

FileStatus[] listStatus = fs.listStatus(new Path("/"));
for(FileStatus file :listStatus){

System.out.println("name: " + file.getPath().getName());
System.out.println((file.isFile()?"file":"directory"));

}

public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://mini1:9000");
//拿到一个文件系统操作的客户端实例对象
FileSystem fs = FileSystem.get(conf);

fs.copyFromLocalFile(new Path("c:/access.log"), new Path("/access.log.copy"));
fs.close();
}

}

巴特西

HDFS api操作

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