文件相关API

package HDFS;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.io.IOUtils;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * @Author:Dapeng
 * @Discription:
 * @Date:Created in 上午 10:37 2018/10/25 0025
 */
public class HDFSAPI {
    /**
     * 生成文件系统
     * */
    public static FileSystem getHadoopFileSystem() {
        Configuration conf  = new Configuration();
        conf.set("fs.defaultFS","hdfs://192.168.52.135:9000");
        // conf.set("dfs.replication","1");
        FileSystem fileSystem = null;
        try {
            fileSystem = FileSystem.get(conf);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return fileSystem;
    }

    /**
     * 创建目录
     * */
    public static boolean createPath(String pathName)  {
        boolean result = false;

        //获取文件系统
        FileSystem fileSystem = getHadoopFileSystem();

        //调用 makdirs创建目录
        Path path = new Path(pathName);
        try {
            result = fileSystem.mkdirs(path);
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //将文件系统关闭
            close(fileSystem);
        }

        return result;
    }

    /**
     * 创建文件写数据
     * */
    public static boolean createFile(String fileName,String content){
        boolean result =  false;
        FileSystem fileSystem = getHadoopFileSystem();
        Path path = new Path(fileName);
        try {
            //创建文件的函数
            FSDataOutputStream fsDataOutputStream = fileSystem.create(path);
            //写入数据
            fsDataOutputStream.writeUTF(content);
            result = true;
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            close(fileSystem);
        }
        return result;
    }

    /**
     * 上传已有的文件
     *
     * */
    public static boolean putFileToHDFS2(String srcPathName,String dstPathName){
        boolean result = false;
        //获得文件系统
        FileSystem fileSystem = getHadoopFileSystem();

        //调用copyFromLocalFile
        try {
            fileSystem.copyFromLocalFile(new Path(srcPathName),new Path(dstPathName));
            result = true;
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭文件系统
            close(fileSystem);
        }
        return result;
    }
    /**
     * @Author:Dapeng
     * @Description:    上传文件通过输入输出流
     */
    public static boolean putFileToHDFS(String srcPathName , String dstPathName){
        boolean result = false;
        //获取文件系统
        FileSystem fileSystem = getHadoopFileSystem();

        //上传
        try {
            //创建一个到HDFS的输出流
            FSDataOutputStream out = fileSystem.create(new Path(dstPathName));
            //创建一个本地java的输入流
            FileInputStream in = new FileInputStream(srcPathName);

            //通过一个IOUtilsd的copyBytes方法传递数据流
            IOUtils.copyBytes(in,out,4096,true);
            result = true;

        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭文件系统
            close(fileSystem);
        }
        return result;
    }
    /**
     * @Author:Dapeng
     * @Description:        文件元数据
     */
    public static FileStatus[] list(String dstPathName){
        FileStatus[] list = null;
        //获取文件系统
        FileSystem fileSystem = getHadoopFileSystem();

        //获取元数据信息
        try {
            list = fileSystem.listStatus(new Path(dstPathName));
            for(FileStatus fileStatus : list) {
                //可以返回相关的一些信息
//                fileStatus.isDirectory();
//                fileStatus.isFile();
//                fileStatus.getPath().toString();
//                fileStatus.getReplication();
                System.out.println(fileStatus);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            //关闭文件系统
            close(fileSystem);
        }

        return list;
    }
    /**
     * @Author:Dapeng
     * @Description:    下载文件通过输入输出流
     */
    public static boolean getFileFromHDFS(String srcPathName , String dstPathName){
        boolean result = false;
        //获取文件系统
        FileSystem fileSystem = getHadoopFileSystem();

        //下载文件
        try {
            //读入到内存
            FSDataInputStream in = fileSystem.open(new Path(srcPathName));
            //写入到文件
            FileOutputStream out = new FileOutputStream(dstPathName);
            //通过工具类链接两者
            IOUtils.copyBytes(in,out,4096,true);

            result = true;
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            //关闭文件系统
            close(fileSystem);
        }

        return result;

    }

    /**
     * @Author:Dapeng
     * @Description:    删除文件
     */
    public static boolean delete(String path){
        boolean result = false;
        //获取文件系统
        FileSystem fileSystem = getHadoopFileSystem();

        //删除,第二个参数是否递归的删除
        try {
            fileSystem.delete(new Path(path) ,true);
            result = true;
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            close(fileSystem);
        }
        return result;
        //关闭文件系统
    }
    /**
     * @Author:Dapeng
     * @Description:    关闭文件系统
     */
    public static void close(FileSystem fileSystem){
        try {
            fileSystem.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}