ssh - 如何通过 java 的 hdfs 协议(protocol)访问 hadoop？

Question

我找到了一种通过 hftp 连接到 hadoop 的方法，它工作正常，(只读):

uri = "hftp://172.16.xxx.xxx:50070/";

System.out.println( "uri: " + uri );           
Configuration conf = new Configuration();

FileSystem fs = FileSystem.get( URI.create( uri ), conf );
fs.printStatistics();

但是，我想读/写以及复制文件，也就是说，我想通过 hdfs 连接。如何启用 hdfs 连接以便我可以编辑实际的远程文件系统？

我试图从 hftp -> hdfs 更改上面的协议(protocol)，但出现以下异常 ...

(请原谅我对 url 协议(protocol)和 hadoop 的了解不足，我认为这是我问的一个有点奇怪的问题，但我们将不胜感激任何帮助!)

Exception in thread "main" java.io.IOException: Call to /172.16.112.131:50070 failed on local exception: java.io.EOFException at org.apache.hadoop.ipc.Client.wrapException(Client.java:1139) at org.apache.hadoop.ipc.Client.call(Client.java:1107) at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:226) at $Proxy0.getProtocolVersion(Unknown Source) at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:398) at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:384) at org.apache.hadoop.hdfs.DFSClient.createRPCNamenode(DFSClient.java:111) at org.apache.hadoop.hdfs.DFSClient.(DFSClient.java:213) at org.apache.hadoop.hdfs.DFSClient.(DFSClient.java:180) at org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:89) at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1514) at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:67) at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:1548) at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1530) at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:228) at sb.HadoopRemote.main(HadoopRemote.java:24)

Answer 1

把你要打的hadoop的core-site.xml和hdfs-site.xml加到conf里就行了像这样:

import java.net.URI;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.testng.annotations.Test;

/**
 * @author karan
 *
 */
public class HadoopPushTester {

    @Test
    public void run() throws Exception {

        Configuration conf = new Configuration();

        conf.addResource(new Path("src/test/resources/HadoopConfs/core-site.xml"));
        conf.addResource(new Path("src/test/resources/HadoopConfs/hdfs-site.xml"));

        String dirName = "hdfs://hosthdfs:port/user/testJava";

        // Values of hosthdfs:port can be found in the core-site.xml  in the fs.default.name
        FileSystem fileSystem = FileSystem.get(conf);


        Path path = new Path(dirName);
        if (fileSystem.exists(path)) {
            System.out.println("Dir " + dirName + " already exists");
            return;
        }

        // Create directories
        fileSystem.mkdirs(path);

        fileSystem.close();
    }
}