<span style="font-size:32px;color:#ff0000;">說明：本測試使用maven管理專案結構，測試前，請把 core-site.xml 拷貝到resource目錄</span>

<span style="font-size:18px;">package hadoop.test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class Hdfstest {

	public Hdfstest() throws IOException{
		// 創建於hdfs的連線（操作）物件
		hdfs = FileSystem.get(conf) ; 
	}
	
	//配置hadoop配置資訊物件
	public final Configuration conf = new Configuration();
	// 宣告hdfs檔案系統操作物件
	public FileSystem hdfs ;
	
	public void createHdfsFile(String path) throws IOException{
		
		Path p = new Path(path);
		// 根據path建立檔案
		FSDataOutputStream od = hdfs.create(p) ;
		//od.writeUTF("hello" );
		od.write("gbdghrherghr".getBytes());
		
	}
</span>
 

<span style="font-size:18px;"><span style="white-space:pre">	</span>// 內容追加</span>

<span style="font-size:18px;">	public void appendHdfsFile(String path,String content) throws IOException{
		Path p = new Path(path) ;
		FSDataOutputStream os = hdfs.append(p) ;
		os.write(content.getBytes());
	}
	    // 檔案讀取
	public void readHdfsFile(String path) throws IOException{
		Path p = new Path(path) ;
		FSDataInputStream fp = hdfs.open(p) ;
		InputStreamReader isr = new InputStreamReader(fp) ;
		BufferedReader br = new BufferedReader(isr) ;
		String line = br.readLine() ;
		while(line !=null){
			System.out.println(line);
			line = br.readLine() ;
		}
	
	}
	    //  遍歷輸出hdfs目錄
	public void listHdfsFiles(String path) throws IOException{
		Path p = new Path(path);
		//判斷給定的(路徑)目錄是否存在
		boolean isExists = hdfs.exists(p) ;
		if(isExists){
	
			boolean idDirectory = hdfs.isDirectory(p) ;
			boolean isFile = hdfs.isFile(p) ;
			if(idDirectory){
				System.out.println(p);
				FileStatus[] fastatus = hdfs.listStatus(p) ;
				for(FileStatus fs : fastatus){
					Path cp = fs.getPath() ;
					if(path.equals("/")){
						listHdfsFiles(path+cp.getName()) ;
					}else{
						listHdfsFiles(path+"/"+cp.getName()) ;
					}
				}
			}else if(isFile){
				System.out.println(p);
			}
		}
	}
	     //  檔案刪除
	public void deleteHdfsFile(String path) throws IOException{
		Path p = new Path(path);
		hdfs.delete(p, true) ;
		
	}
	
	  // 檔案上傳
	public void uploadFile(String res,String des) throws IOException{
		Path resPath = new Path(res) ;
		Path desPath = new Path(des) ;
		hdfs.copyFromLocalFile(resPath, desPath);
	}
	  // 檔案下載
	public void copyTOLocalFile(String res,String des) throws IOException{
		Path resPath = new Path(res) ;
		Path desPath = new Path(des) ;
		hdfs.copyToLocalFile(resPath, desPath);
	}
	
	public static void main(String[] args) throws IOException {
		Hdfstest dfstest =new Hdfstest();
	//	dfstest.createHdfsFile("/hdfstest");
		// 內容追加
	//	dfstest.appendHdfsFile("/hdfstest", "\n 34638767896");
		
	//	dfstest.readHdfsFile("/hdfstest") ;
		
	//	dfstest.listHdfsFiles("/") ;
		
	//	dfstest.deleteHdfsFile("/hdfstest") ;
		
	//	dfstest.uploadFile("D:\\KuGou","/user/root/input") ;
		dfstest.copyTOLocalFile("/user/root/input/KuGou","D:\\KuGou") ;
		
		dfstest.hdfs.close();
	}
}
</span>