Java操作HDFS

Java操作HDFS

```java
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.fs.permission.FsPermission;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;

public class TestHdfsApi {
    /**
     * 使用java操作HDFS
     * 创建文件夹，上传文件，下载文件，列出日志，查看block块的信息
     *
     * @param args
     */
    public static void main(String[] args) throws IOException {
        Configuration conf = new Configuration();//org.apache.hadoop.conf
        //配置主节点信息
        conf.set("fs.defaultFS","hdfs://master01:9000");
        //通过hadoop提供的FileSystem抽象类中的方法，可以根据我们自己提供的配置来获取操作hdfs的对象
        FileSystem fs = FileSystem.get(conf);

        boolean b = fs.mkdirs(new Path("/shujia/bigdata19/"));
        System.out.println(b);

        //上传文件-本地文件路径写绝对路径
//        fs.copyFromLocalFile(new Path("F:\\software\\IdeaProjects\\bigdata19-project\\bigdata19-hadoop\\src\\data\\students.txt"),new Path("/shujia/bigdata19/students.txt"));

        //下载文件
//        fs.copyToLocalFile(new Path("/shujia/bigdata19/students.txt"),new Path("F:\\software\\IdeaProjects\\bigdata19-project\\bigdata19-hadoop\\src\\data\\students2.txt"));

        //列出当前目录下所有文件
        RemoteIterator<LocatedFileStatus> listFiles = fs.listFiles(new Path("/shujia/bigdata19"), true);
        while (listFiles.hasNext()){
            LocatedFileStatus fileStatus = listFiles.next();
            BlockLocation[] blockLocations = fileStatus.getBlockLocations();
            for (BlockLocation location : blockLocations) {
                String[] names = location.getNames();
                String s = Arrays.toString(names);
                System.out.println(s);
            }
            //获取文件所属用户
            System.out.println(fileStatus.getOwner());
            //获取文件的名字
            String name = fileStatus.getPath().getName();
            System.out.println(name);
            //获取文件的权限
            FsPermission permission = fileStatus.getPermission();
            System.out.println(permission);
            //获取文件最后修改的时间
            long accessTime = fileStatus.getAccessTime();
            System.out.println(accessTime);
            Date date = new Date(accessTime);
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            System.out.println(sdf.format(date));


        }

        //释放资源
        fs.close();



    }
}