Java 封装 HDFS API 操作

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一：环境介绍

hadoop：2.6

Ubuntu：15.10

eclipse：3.8.1

二：操作包含

推断某个目录是否存在              isExist(folder);

创建目录                                    mkdir(folder);

删除目录                                    rmr(folder);

列出全部目录                 ls(folder);

递归列出全部目录                      lsr(folder);

上传文件                                        put(local, folder);

下载文件                                        get(folder,local1);

删除文件                                        rm(folder);

显示文件                                        cat(folder);

三：代码演示

package user_thing_tuijian;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
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 hdfsGYT {

	private static  final String HDFS = "hdfs://127.0.0.1:9000/";

	public hdfsGYT(String hdfs,  Configuration conf ){
		this.hdfsPath = hdfs;
		this.conf = conf;
	}

	public hdfsGYT() {
		// TODO Auto-generated constructor stub
	}

	private String hdfsPath;
	private Configuration conf = new Configuration() ;

	public static void main(String[] args) throws IOException, URISyntaxException{
		hdfsGYT hdfsgyt = new hdfsGYT();
		String folder = HDFS + "mr/groom_system/small2.csv";
		String local = "/home/thinkgamer/Java/hadoop_shizhan/src/user_thing_tuijian/small2.csv";
		String local1 = "/home/thinkgamer/Java/hadoop_shizhan/src/user_thing_tuijian";
		//推断某个目录是否存在
		//hdfsgyt.isExist(folder);
		//创建目录
		//hdfsgyt.mkdir(folder);
		//删除目录
		//hdfsgyt.rmr(folder);
		//列出全部目录
		//hdfsgyt.ls(folder);
		//递归列出全部目录
		//hdfsgyt.lsr(folder);
		//上传文件
		//hdfsgyt.put(local, folder);
		//下载文件
		//hdfsgyt.get(folder,local1);
		//删除文件
		//hdfsgyt.rm(folder);
		//显示文件
		//hdfsgyt.cat(folder);
	}

	//显示文件
	private void cat(String folder) throws IOException, URISyntaxException {
		// 与hdfs建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS),new Configuration());
		Path path = new Path(folder);
		 FSDataInputStream fsdis = null;
	        System.out.println("cat: " + folder);
	        try {
	            fsdis =fs.open(path);
	            IOUtils.copyBytes(fsdis, System.out, 4096, false);
	          } finally {
	            IOUtils.closeStream(fsdis);
	            fs.close();
	          }
	}

	//删除文件
	private void rm(String folder) throws IOException, URISyntaxException {
		//与hdfs建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS),new Configuration());
		Path path = new Path(folder);
		if(fs.deleteOnExit(path)){
			fs.delete(path);
			System.out.println("delete:" + folder);
		}else{
			System.out.println("The fiel is not exist!");
		}
		fs.close();
	}

	//下载文件
	private void get(String remote,  String local) throws IllegalArgumentException, IOException, URISyntaxException {
		// 建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS), new Configuration());
		fs.copyToLocalFile(new Path(remote), new Path(local));
		System.out.println("Get From :   " + remote  + "   To :" + local);
		fs.close();
	}

	//上传文件
	private void put(String local, String remote) throws IOException, URISyntaxException {
		// 建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS), new Configuration());
		fs.copyFromLocalFile(new Path(local), new Path(remote));
		System.out.println("Put :" + local  + "   To : " + remote);
		fs.close();
	}

	//递归列出全部目录
	private void lsr(String folder) throws IOException, URISyntaxException {
		//与hdfs建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS),new Configuration());
		Path path = new Path(folder);
		//得到该目录下的全部文件
		FileStatus[] fileList = fs.listStatus(path);
		for (FileStatus f : fileList) {
            System.out.printf("name: %s   |   folder: %s  |   size: %d\n", f.getPath(),  f.isDir() , f.getLen());
            try{
            	FileStatus[] fileListR = fs.listStatus(f.getPath());
            	for(FileStatus fr:fileListR){
                    System.out.printf("name: %s   |   folder: %s  |   size: %d\n", fr.getPath(),  fr.isDir() , fr.getLen());
            	}
            }finally{
            	continue;
            }
        }
		fs.close();
	}

	//列出全部目录
	private void ls(String folder) throws IOException, URISyntaxException {
		//与hdfs建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS),new Configuration());
		Path path = new Path(folder);
		//得到该目录下的全部文件
		FileStatus[] fileList = fs.listStatus(path);
		for (FileStatus f : fileList) {
            System.out.printf("name: %s   |   folder: %s  |   size: %d\n", f.getPath(),  f.isDir() , f.getLen());
        }
		fs.close();
	}

	//删除目录
	private void rmr(String folder) throws IOException, URISyntaxException {
		//与hdfs建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS),new Configuration());
		Path path = new Path(folder);
		fs.delete(path);
		System.out.println("delete:" + folder);
		fs.close();
	}

	//创建目录
	public void mkdir(String folder) throws IOException, URISyntaxException {
		//与hdfs建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS),new Configuration());
		Path path = new Path(folder);
		if (!fs.exists(path)) {
			fs.mkdirs(path);
			System.out.println("Create: " + folder);
		}else{
			System.out.println("it is have exist:" + folder);
		}
		fs.close();
	}

	//推断某个目录是否存在
	private void isExist(String folder) throws IOException, URISyntaxException {
		//与hdfs建立联系
		FileSystem fs = FileSystem.get(new URI(HDFS),new Configuration());
		Path path = new Path(folder);
		if(fs.exists(path)){
			System.out.println("it is have exist:" + folder);
		}else{
			System.out.println("it is not exist:" + folder);
		}
		fs.close();
	}

}