学步园

package hadoop.test;

import java.io.IOException;
import java.net.URI;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.BlockLocation;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;

public class FileSystemTest {

            private static final String hadoop_url = "hdfs://localhost:9000";
            private static FileSystem fs = null;

            static {
                        Configuration configuration = new Configuration();
                        try {
                                    fs = FileSystem.get(URI.create(hadoop_url), configuration);
                        } catch (IOException ex) {
                                    ex.printStackTrace();
                        }
            }

            //创建目录
            public static void mkdirs() throws IOException {
                        Path path = new Path("/mytest");
                        boolean flag = fs.mkdirs(path);
                        System.out.println(flag ? "success" : "failure");
            }

            //创建文件  如果文件存在会覆盖
            public static void mkFile() throws IOException {
                        Path path = new Path("/mytest/test.txt");
                        //     fs.create(path);
                        FSDataOutputStream outputStream = fs.create(path);
                        outputStream.write("Hello World !".getBytes());
                        IOUtils.closeStream(outputStream);

            }

            //重命名  文件/文件夹
            public static void rename() throws IOException {
                        Path oldFile = new Path("/mytest/test.txt");
                        Path newFile = new Path("/mytest/t.txt");
                        boolean flag = fs.rename(oldFile, newFile);
            }

            //删除  文件/文件夹
            public static void delete() throws IOException {
                        Path path = new Path("/mytest/t.txt");
                        boolean flag = fs.delete(path);

            }

            //上传/下载文件到HDFS
            public static void upload() throws IOException {
                        Path path = new Path("/mytest/a.txt");
                        Path src = new Path("/home/zcwangjb/t.txt");
                        fs.copyFromLocalFile(src, path);
            }

            //查看文件在集群中的位置
            public static void location() throws IOException {
                        Path path = new Path("/mytest/a.txt");
                        boolean flag = fs.exists(path);    //文件是否存在
                        if (flag) {
                                    FileStatus fileStatus = fs.getFileStatus(path);
                                    //fileStatus.
                                    BlockLocation[] blockLocations = fs.getFileBlockLocations(fileStatus, 0, fileStatus.getLen());
                                    for (int i = 0; i < blockLocations.length; i++) {
                                                String[] hosts = blockLocations[i].getHosts();
                                                System.out.println("host:" + i + "====" + hosts[0]);
                                    }
                        }
            }

            public static void main(String[] args) throws IOException {
                        FileSystemTest test = new FileSystemTest();
                        //mkdirs();
                        mkFile();
                        // rename();
                        //delete();
                        // upload();
                        location();
            }

}