大数据从入门到实战——分布式文件系统HDFS

• 第2关 HDFS-JAVA接口之读取文件
• 第3关 HDFS-JAVA接口之上传文件
• 第4关 HDFS-JAVA接口之删除文件

package step2;

import java.io.IOException;
import java.io.InputStream;
import java.net.URI;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;


public class FileSystemCat {
	
	public static void main(String[] args) throws IOException {
		//请在Begin-End之间添加你的代码，完成任务要求。
        
		
		URI uri = URI.create("hdfs://localhost:9000/user/hadoop/task.txt");
    	Configuration config = new Configuration();
    	FileSystem fs = FileSystem.get(uri, config);
    	InputStream in = null;
    try {
        in = fs.open(new Path(uri));
        IOUtils.copyBytes(in, System.out, 2048, false);
    } catch (Exception e) {
        IOUtils.closeStream(in);
	}
		
		
		
	}
}

package step3;


import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.io.File;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.util.Progressable;


public class FileSystemUpload {
	
	public static void main(String[] args) throws IOException {
		//请在 Begin-End 之间添加代码，完成任务要求。
        
		File localPath = new File("/develop/input/hello.txt");
		String hdfsPath = "hdfs://localhost:9000/user/tmp/hello.txt";

		InputStream in = new BufferedInputStream(new FileInputStream(localPath));
		Configuration config = new Configuration();
		FileSystem fs = FileSystem.get(URI.create(hdfsPath), config);
		long fileSize = localPath.length() > 65536 ? localPath.length() / 65536 : 1;
		FSDataOutputStream out = fs.create(new Path(hdfsPath), new Progressable() {
			long fileCount = 0;
			public void progress() {
				System.out.println("总进度" + (fileCount / fileSize) * 100 +"%");
				fileCount++;
			}
		});
		IOUtils.copyBytes(in, out, 2048, true);
		
		
		
	}
}

String uri ="hdfs://localhost:9000/";
String path1="hdfs://localhost:9000/tmp";
String path2="hdfs://localhost:9000/tmp/test";
Configuration config = new Configuration();
FileSystem fs = FileSystem.get(URI.create(uri),config);
fs.delete(new Path(path2),true);
Path[] paths = {new Path(uri),new Path(path1)};
FileStatus[] status = fs.listStatus(paths);
Path[] listPaths = FileUtil.stat2Paths(status);

for (Path path : listPaths){
System.out.println(path);
}