package com.test;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Date;
public class HelloHadoopDemo {
public static String fileName;
public static void main(String[] args) throws URISyntaxException, IOException, InterruptedException {
createHDFS();
readHDFS();
return;
}
private static void createHDFS() throws URISyntaxException, IOException, InterruptedException {
Configuration configuration = new Configuration();
// configuration.set("fs.hdfs.impl","org.apache.hadoop.hdfs.DistributedFileSystem");
String path = "hdfs://127.0.0.1:9000/first/hello/";
URI uri = new URI(path);
FileSystem fileSystem = FileSystem.get(uri, configuration, "root");//user不是root,没有权限写
fileName = "file" + new Date().getTime();
FSDataOutputStream fsDataOutputStream = fileSystem.create(new Path(path + fileName), false);
String json = "hello hadoop";
fsDataOutputStream.write(json.getBytes());
fsDataOutputStream.close();
System.out.println(fileName);
// Thread.sleep(3000L);
}
private static void readHDFS() throws URISyntaxException, IOException, InterruptedException {
String path = "hdfs://127.0.0.1:9000/first/hello/";
URI uri = new URI(path);
FileSystem fileSystem = FileSystem.get(uri, new Configuration());//user不是root,没有权限写
FSDataInputStream fsDataInputStream = fileSystem.open(new Path(path + fileName));
byte[] bytes = new byte[1024];
int length = -1;
while((length=fsDataInputStream.read(bytes)) != -1){
String s = new String(bytes, 0, length);
System.out.println(s);
}
}
}
Hadoop读写HDFS的Java Demo
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转载自blog.csdn.net/yzh_1346983557/article/details/81120407
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