java - 在Java中访问HDFS文件系统的异常

Question

我尝试使用Java API通过以下代码访问HDFS文件:

import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.FSDataInputStream;

public static void main(args[]) {
    Configuration conf = new Configuration();
    conf.addResource(new Path("/etc/hadoop/conf/core-site.xml"));
    conf.addResource(new Path("/etc/hadoop/conf/hdfs-site.xml"));

    try {
        Path path = new Path("hdfs://mycluster/user/mock/test.txt");
        FileSystem fs = FileSystem.get(path.toUri(), conf);
        if (fs.exists(path)) {
            FSDataInputStream inputStream = fs.open(path);
            // Process input stream ...
        }
        else
            System.out.println("File does not exist");
    } catch (IOException e) {
       System.out.println(e.getMessage());

FileSystem.get(path.toUri(), conf)发生异常，指出Couldn't create proxy provider class org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider由java.lang.NoClassDefFoundError: Could not initialize class org.apache.hadoop.security.Credentials引起。

我没有找到有关该错误的更多信息。是由于错误的API(org.apache.hadoop.hdfs而不是org.apache.hadoop.fs)导致的问题？

Answer 1

1)您的类路径中是否有hadoop-hdfs-.jar？

2)如何下载依赖项？ Maven /手动/其他

3)能否请您提供stacktrace？