我尝试使用java api访问hdfs文件，代码如下：

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());

在发生异常 FileSystem.get(path.toUri(), conf) 这么说 Couldn't create proxy provider class org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider 这是由 java.lang.NoClassDefFoundError: Could not initialize class org.apache.hadoop.security.Credentials .
我没有找到多少关于这个错误的信息。问题是由于错误的api引起的吗( org.apache.hadoop.hdfs 而不是 org.apache.hadoop.fs )?