Question

我正在尝试连接到远程HDFS实例

        Configuration conf = new Configuration();
        conf.set("fs.defaultFS", "hdfs://hostName:8020");
        conf.set("fs.hdfs.impl", "org.apache.hadoop.hdfs.DistributedFileSystem");
        FileSystem fs = FileSystem.get(conf);
        RemoteIterator<LocatedFileStatus> ri = fs.listFiles(fs.getHomeDirectory(), false);
        while (ri.hasNext()) {
            LocatedFileStatus lfs = ri.next();
            //log.debug(lfs.getPath().toString());
        }

        fs.close();

这是我的Maven依赖项

<dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-mapreduce-client-core</artifactId>
        <version>2.7.1</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-client</artifactId>
        <version>2.7.1</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-examples</artifactId>
        <version>1.2.1</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-hdfs</artifactId>
        <version>2.7.1</version>
    </dependency>

这是我的远程节点上的hadoop version命令的结果

hadoop version
Hadoop 2.7.1.2.3.0.0-2557

但是我得到了

Exception in thread "main" java.lang.UnsupportedOperationException: Not implemented by the DistributedFileSystem FileSystem implementation
at org.apache.hadoop.fs.FileSystem.getScheme(FileSystem.java:217)
at org.apache.hadoop.fs.FileSystem.loadFileSystems(FileSystem.java:2624)
at org.apache.hadoop.fs.FileSystem.getFileSystemClass(FileSystem.java:2634)
at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:2651)
at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:92)
at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:2687)
at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2669)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:371)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:170)
at filecheck.HdfsTest.main(HdfsTest.java:21)

这是导致错误的行

FileSystem fs = FileSystem.get(conf);

知道为什么会这样吗？

尝试了Manjunath的回答

这是我得到的

ERROR util.Shell: Failed to locate the winutils binary in the hadoop binary path
java.io.IOException: Could not locate executable null\bin\winutils.exe in the Hadoop binaries.
    at org.apache.hadoop.util.Shell.getQualifiedBinPath(Shell.java:356)
    at org.apache.hadoop.util.Shell.getWinUtilsPath(Shell.java:371)
    at org.apache.hadoop.util.Shell.<clinit>(Shell.java:364)
    at org.apache.hadoop.util.StringUtils.<clinit>(StringUtils.java:80)
    at org.apache.hadoop.fs.FileSystem$Cache$Key.<init>(FileSystem.java:2807)
    at org.apache.hadoop.fs.FileSystem$Cache$Key.<init>(FileSystem.java:2802)
    at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2668)
    at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:371)
    at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:170)
    at filecheck.HdfsTest.main(HdfsTest.java:27)
15/11/16 09:48:23 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Exception in thread "main" java.lang.IllegalArgumentException: Pathname  from hdfs://hostName:8020 is not a valid DFS filename.
    at org.apache.hadoop.hdfs.DistributedFileSystem.getPathName(DistributedFileSystem.java:197)
    at org.apache.hadoop.hdfs.DistributedFileSystem.access$000(DistributedFileSystem.java:106)
    at org.apache.hadoop.hdfs.DistributedFileSystem$DirListingIterator.<init>(DistributedFileSystem.java:940)
    at org.apache.hadoop.hdfs.DistributedFileSystem$DirListingIterator.<init>(DistributedFileSystem.java:927)
    at org.apache.hadoop.hdfs.DistributedFileSystem$19.doCall(DistributedFileSystem.java:872)
    at org.apache.hadoop.hdfs.DistributedFileSystem$19.doCall(DistributedFileSystem.java:868)
    at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
    at org.apache.hadoop.hdfs.DistributedFileSystem.listLocatedStatus(DistributedFileSystem.java:886)
    at org.apache.hadoop.fs.FileSystem.listLocatedStatus(FileSystem.java:1694)
    at org.apache.hadoop.fs.FileSystem$6.<init>(FileSystem.java:1787)
    at org.apache.hadoop.fs.FileSystem.listFiles(FileSystem.java:1783)
    at filecheck.HdfsTest.main(HdfsTest.java:29)

Answer 1

我的HDFS客户端代码使用hadoop-hdfs也需要：

    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-common</artifactId>
        <version>2.7.1</version>
    </dependency>

我使用的是Hortonworks存储库：

    <repository>
        <id>repo.hortonworks.com</id>
        <name>Hortonworks HDP Maven Repository</name>
        <url>http://repo.hortonworks.com/content/repositories/releases/</url>
    </repository>

我认为您正在选择错误版本的FileSystem。

Answer 2

FileSystem.java方法中的getScheme()异常发生异常，只会引发UnsupportedOperationException异常。

  public String getScheme() {
    throw new UnsupportedOperationException("Not implemented by the " + getClass().getSimpleName() + " FileSystem implementation");
  }

它正在调用getScheme()类的FileSystem方法，而不是从getScheme()类调用DistributedFileSystem方法。

getScheme()类的DistributedFileSystem方法返回：

@Override
  public String getScheme() {
    return HdfsConstants.HDFS_URI_SCHEME;
  }

因此，要解决此问题，您需要更改“FileSystem.get（conf）”语句，如下所示：

DistributedFileSystem fs = (DistributedFileSystem) FileSystem.get(conf);

修改

我试用了这个程序，它对我来说非常好。事实上，无论是否有铸造，它都可以使用。以下是我的代码（唯一不同的是，我将递归列表设置为“true”）：

package com.hadooptests; import org.apache.hadoop.conf.Configuration; 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.apache.hadoop.hdfs.DistributedFileSystem; import java.io.IOException; public class HDFSConnect { public static void main(String[] args) { Configuration conf = new Configuration(); conf.set("fs.defaultFS", "hdfs://machine:8020"); conf.set("fs.hdfs.impl", "org.apache.hadoop.hdfs.DistributedFileSystem"); DistributedFileSystem fs = null; try { fs = (DistributedFileSystem) FileSystem.get(conf); RemoteIterator<LocatedFileStatus> ri; ri = fs.listFiles(new Path("hdfs://machine:8020/"), true); while (ri.hasNext()) { LocatedFileStatus lfs = ri.next(); System.out.println(lfs.getPath().toString()); } fs.close(); } catch (IOException e) { e.printStackTrace(); } } }

我的妈妈：

<dependencies> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-hdfs</artifactId> <version>2.7.1</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>2.7.1</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-core</artifactId> <version>1.2.1</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <version>2.6</version> <configuration> <archive> <manifest> <mainClass>com.hadooptests.HDFSConnect </mainClass> </manifest> </archive> </configuration> </plugin> </plugins> </build>

我将程序运行为：

java -cp "%CLASSPATH%;hadooptests-1.0-SNAPSHOT.jar" com.hadooptests.HDFSConnect

其中CLASSPATH设置为： .;%HADOOP_HOME%\etc\hadoop\;%HADOOP_HOME%\share\hadoop\common\*;%HADOOP_HOME%\share\hadoop\common\lib\*;%HADOOP_HOME%\share\hadoop\hdfs\*;%HADOOP_HOME%\share\hadoop\hdfs\lib\*;%HADOOP_HOME%\share\hadoop\mapreduce\*;%HADOOP_HOME%\share\hadoop\mapreduce\lib\*;%HADOOP_HOME%\share\hadoop\tools\*;%HADOOP_HOME%\share\hadoop\tools\lib\*;%HADOOP_HOME%\share\hadoop\yarn\*;%HADOOP_HOME%\share\hadoop\yarn\lib\*

我得到了一些输出：

hdfs://machine:8020/app-logs/machine/logs/application_1439815019232_0001/machine.corp.com_45454 hdfs://machine:8020/app-logs/machine/logs/application_1439815019232_0002/machine.corp.com_45454 hdfs://machine:8020/app-logs/machine/logs/application_1439817471006_0002/machine.corp.com_45454 hdfs://machine:8020/app-logs/machine/logs/application_1439817471006_0003/machine.corp.com_45454

编辑2：

我的环境：

Windows上的Hadoop 2.7.1。

我安装了HDP 2.3.0，它部署了Hadoop 2.7.1

无法从Windows连接到远程HDFS

2 个答案: