import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URI;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.BlockLocation;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
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;
public class HdfsClient {
FileSystem fs = null;
@Before
public void init() throws Exception {
// 构造一个配置参数对象，设置一个参数：我们要访问的hdfs的URI
// 从而FileSystem.get()方法就知道应该是去构造一个访问hdfs文件系统的客户端，以及hdfs的访问地址
// new Configuration();的时候，它就会去加载jar包中的hdfs-default.xml
// 然后再加载classpath下的hdfs-site.xml
Configuration conf = new Configuration();
// conf.set(“fs.defaultFS”, “hdfs://mini1:9000”);
/**
- 参数优先级： 1、客户端代码中设置的值 2、classpath下的用户自定义配置文件 3、然后是服务器的默认配置
*/
/conf.set(“dfs.replication”, “2”);
conf.set(“dfs.block.size”, “64m”);/
// 获取一个hdfs的访问客户端，根据参数，这个实例应该是DistributedFileSystem的实例
// fs = FileSystem.get(conf);
// 如果这样去获取，那conf里面就可以不要配”fs.defaultFS”参数，而且，这个客户端的身份标识已经是root用户
fs = FileSystem.get(new URI(“hdfs://mini1:9000”), conf, “root”);
// 获取文件系统相关信息
/*
- DatanodeInfo[] dataNodeStats = ((DistributedFileSystem)
- fs).getDataNodeStats(); for(DatanodeInfo dinfo: dataNodeStats){
- System.out.println(dinfo.getHostName()); }
*/
}
/**
- 往hdfs上传文件
- @throws Exception
*/
@Test
public void testAddFileToHdfs() throws Exception {
// 要上传的文件所在的本地路径
// 要上传到hdfs的目标路径*/
Path src = new Path(“e:/mysql-connector-java-5.1.28.jar”);
Path dst = new Path(“/”);
fs.copyFromLocalFile(src, dst);
fs.close();
}
/**
- 通过流的形式往hdfs上传数据
- @throws Exception
*/
@SuppressWarnings(“resource”)
@Test
public void testAddFileToHdfs2() throws Exception {
FileInputStream in = new FileInputStream(“d://123456.txt”);
Path path = new Path(“/123456.txt”);
FSDataOutputStream out = fs.create(path);
IOUtils.copy(in, out);
fs.close();
}
/**
- 从hdfs中复制文件到本地文件系统
- @throws IOException
- @throws IllegalArgumentException
*/
@Test
public void testDownloadFileToLocal() throws IllegalArgumentException, IOException {
// fs.copyToLocalFile(new Path(“/mysql-connector-java-5.1.28.jar”), new
// Path(“d:/”));
fs.copyToLocalFile(false, new Path(“/mysql-connector-java-5.1.28.jar”), new Path(“d:/”), true);
fs.close();
}
/**
- 通过流的形式从hdfs下载数据
- @throws Exception
*/
@SuppressWarnings(“resource”)
@Test
public void testDownloadFileToLocal2() throws Exception {
FSDataInputStream in = fs.open(new Path(“/123456.txt”));
FileOutputStream out = new FileOutputStream(new File(“d:/a.txt”));
IOUtils.copy(in, out);
fs.close();
}
/**
- 目录操作
- @throws IllegalArgumentException
- @throws IOException
*/
@Test
public void testMkdirAndDeleteAndRename() throws IllegalArgumentException, IOException {
// 创建目录
fs.mkdirs(new Path(“/nihao/henhao/yeah”));
// // 删除文件夹 ，如果是非空文件夹，参数2必须给值true
//fs.delete(new Path(“/nihao/henhao”), true);
//
// // 重命名文件或文件夹
// fs.rename(new Path(“/a1”), new Path(“/a2”));
}
/**
- 查看目录信息，只显示文件
- @throws IOException
- @throws IllegalArgumentException
- @throws FileNotFoundException
*/
@Test
public void testListFiles() throws FileNotFoundException, IllegalArgumentException, IOException {
// 思考：为什么返回迭代器，而不是List之类的容器
RemoteIterator listFiles = fs.listFiles(new Path(“/”), true);
while (listFiles.hasNext()) {
LocatedFileStatus fileStatus = listFiles.next();
System.out.println(fileStatus.getPath().getName());
System.out.println(fileStatus.getBlockSize());
System.out.println(fileStatus.getPermission());
System.out.println(fileStatus.getLen());
BlockLocation[] blockLocations = fileStatus.getBlockLocations();
for (BlockLocation bl : blockLocations) {
System.out.println(“block-length:” + bl.getLength() + “–” + “block-offset:” + bl.getOffset());
String[] hosts = bl.getHosts();
for (String host : hosts) {
System.out.println(host);
}
}
System.out.println(“————–为allen打印的分割线————–“);
}
}
/**
- 查看文件及文件夹信息
- @throws IOException
- @throws IllegalArgumentException
- @throws FileNotFoundException
*/
@Test
public void testListAll() throws FileNotFoundException, IllegalArgumentException, IOException {
FileStatus[] listStatus = fs.listStatus(new Path(“/”));
String flag = “”;
for (FileStatus fstatus : listStatus) {
if (fstatus.isFile()) {
flag = “f– “;
} else {
flag = “d– “;
}
System.out.println(flag + fstatus.getPath().getName());
System.out.println(fstatus.getPermission());
}
}