我正在学习scala,我需要写一个自定义文件到hdfs。我在笔记本电脑上使用vmware fusion在cloudera映像上运行自己的hdfs。
这是我的实际代码:
package org.glassfish.samples
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import java.io.PrintWriter;
/**
* @author ${user.name}
* /
object App {
def main(args : Array[String]) {
println( "Trying to write to HDFS..." )
val conf = new Configuration()
val fs= FileSystem.get(conf)
val output = fs.create(new Path("hdfs://quickstart.cloudera:8020/tmp/mySample.txt"))
val writer = new PrintWriter(output)
try {
writer.write("this is a test")
writer.write("\n")
}
finally {
writer.close()
}
print("Done!")
}
}
我得到一个例外:
Caused by: java.lang.IllegalArgumentException: Wrong FS: hdfs://quickstart.cloudera:8020/tmp, expected: file:///
at org.apache.hadoop.fs.FileSystem.checkPath(FileSystem.java:645)
at org.apache.hadoop.fs.RawLocalFileSystem.pathToFile(RawLocalFileSystem.java:80)
at org.apache.hadoop.fs.RawLocalFileSystem.mkdirs(RawLocalFileSystem.java:414)
at org.apache.hadoop.fs.ChecksumFileSystem.mkdirs(ChecksumFileSystem.java:588)
at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:439)
at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:426)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:908)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:889)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:786)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:775)
at org.glassfish.samples.App$.main(App.scala:19)
at org.glassfish.samples.App.main(App.scala)
... 6 more
我可以使用终端和色调访问hdfs
[cloudera@quickstart ~]$ hdfs dfs -ls /tmp
Found 3 items
drwxr-xr-x - hdfs supergroup 0 2015-06-09 17:54 /tmp/hadoop-yarn
drwx-wx-wx - hive supergroup 0 2015-08-17 15:24 /tmp/hive
drwxr-xr-x - cloudera supergroup 0 2015-08-17 16:50 /tmp/labdata
这是我的pom.xml
我使用以下命令运行项目:
mvn清洁包scala:run
我做错了什么?提前谢谢!
在@jeroenr建议后编辑
这是实际代码:
package org.glassfish.samples
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import java.io.PrintWriter;
/**
* @author ${user.name}
* /
object App {
//def foo(x : Array[String]) = x.foldLeft("")((a,b) => a + b)
def main(args : Array[String]) {
println( "Trying to write to HDFS..." )
val conf = new Configuration()
//conf.set("fs.defaultFS", "hdfs://quickstart.cloudera:8020")
conf.set("fs.defaultFS", "hdfs://192.168.30.147:8020")
val fs= FileSystem.get(conf)
val output = fs.create(new Path("/tmp/mySample.txt"))
val writer = new PrintWriter(output)
try {
writer.write("this is a test")
writer.write("\n")
}
finally {
writer.close()
println("Closed!")
}
println("Done!")
}
}
1条答案
按热度按时间8xiog9wr1#
看看这个例子。我认为问题是您没有使用配置默认文件系统
通过相对路径,就像这样:
要写入文件,请直接对fs.create返回的输出流调用“write”,如下所示: