使用java代码实现alluxio-2.8.1版本查看多个挂载点

可以使用Alluxio Java Client中的`FileSystem`类来实现查看多个挂载点，具体代码如下：

import alluxio.client.file.FileSystem;
import alluxio.client.file.options.ListStatusOptions;
import alluxio.conf.InstancedConfiguration;
import alluxio.conf.PropertyKey;
import alluxio.exception.AlluxioException;
import alluxio.uri.Authority;
import alluxio.uri.MultiMasterAuthority;
import alluxio.uri.SingleMasterAuthority;
import alluxio.uri.ZookeeperAuthority;
import alluxio.util.CommonUtils;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class AlluxioMountPoint {
    public static void main(String[] args) throws IOException, AlluxioException {
        InstancedConfiguration conf = InstancedConfiguration.defaults();
        conf.set(PropertyKey.ZOOKEEPER_ADDRESS, "zk://<zk quorum>/alluxio");
        List<String> mountPoints = getMountPoints(conf);
        for(String mountPoint: mountPoints) {
            System.out.println("Mount point: " + mountPoint);
            FileSystem fs = getFileSystem(mountPoint, conf);
            ListStatusOptions options = ListStatusOptions.defaults();
            for (alluxio.client.file.URI uri : fs.listStatus(new alluxio.client.file.URI(mountPoint), options)) {
                System.out.println(uri.getPath());
            }
        }
    }

    private static List<String> getMountPoints(InstancedConfiguration conf) throws IOException, AlluxioException {
        Authority authority = CommonUtils.getAuthority(conf.get(PropertyKey.MASTER_ADDRESS));
        List<Authority> authorities = new ArrayList<>();
        if (authority instanceof SingleMasterAuthority) {
            authorities.add(authority);
        } else if (authority instanceof MultiMasterAuthority) {
            authorities.addAll(((MultiMasterAuthority) authority).getAuthorities());
        } else if (authority instanceof ZookeeperAuthority) {
            authorities.addAll(((ZookeeperAuthority) authority).getAuthorities());
        } else {
            throw new IOException("Unsupported master authority: " + authority);
        }

        List<String> mountPoints = new ArrayList<>();
        for (Authority auth : authorities) {
            try (FileSystem fs = getFileSystem(auth.toString(), conf)) {
                mountPoints.addAll(fs.getMountTable().getMountPoints());
            }
        }
        return mountPoints;
    }

    private static FileSystem getFileSystem(String uri, InstancedConfiguration conf) throws IOException {
        return FileSystem.Factory.create(new alluxio.client.file.URI(uri), conf);
    }
}

其中，`getMountPoints`方法返回所有挂载点的列表，`getFileSystem`方法返回一个连接到指定URI的`FileSystem`对象。在主函数中，我们首先获取所有挂载点，然后遍历每一个挂载点并打印出其中的文件路径。注意，在实际使用中需要将`<zk quorum>`替换成Zookeeper的地址。