java实现从HDFS上下载文件及文件夹的功能，以流形式输出，便于用户自定义保存任何路径下

@[TOC]

java实现下载hdfs文件及文件夹

说明：java实现从HDFS上下载文件及文件夹的功能，以流形式输出，便于用户自定义保存任何路径下

 <!--阿里 FastJson依赖-->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>3.1.1</version>
            <exclusions>
                <exclusion>
                    <artifactId>slf4j-log4j12</artifactId>
                    <groupId>org.slf4j</groupId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-hdfs</artifactId>
            <version>3.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>3.1.1</version>
        </dependency>

==相关类引入jar包，代码上方查看对照即可==

1.下载xxx文件

“下载文件” 执行流程说明：
            1.构建hdfs连接，初始化Configuration
            2.获取文件输入流FSDataInputStream，调用downloadFile()
            3.方法内部先设置header请求头，格式以文件名（convertFileName(fileName)）输出文件，然后输出流内部信息以流的形式输出

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import util.ExportUtil;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
/**
     *  下载文件
     * @author liudz
     * @date 2020/6/9
     * @return 执行结果
     **/
    @RequestMapping(value = "/down", method = RequestMethod.GET)
    public ResponseEntity<InputStreamResource> Test01() throws URISyntaxException, IOException {
        //下面两行，初始化hdfs配置连接
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://172.16.1.9:8020"), conf);
        FSDataInputStream inputStream = fs.open(new Path("hdfs://172.16.1.9:8020/spark/testLog.txt"));
        ResponseEntity<InputStreamResource> result = ExportUtil.downloadFile(inputStream, "testLog.txt");
        return result;
    }

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

import lombok.extern.slf4j.Slf4j;

import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
/**
     * 文件以流的形式读取
     * 
     * @param in 字符输入流
     * @param fileName 文件名字
     * @return 返回结果
     */
    public static ResponseEntity<InputStreamResource> downloadFile(InputStream in, String fileName) {

        try {
            byte[] testBytes = new byte[in.available()];
            HttpHeaders headers = new HttpHeaders();
            headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
            headers.add("Content-Disposition", String.format("attachment; filename=\"%s\"", convertFileName(fileName)));
            headers.add("Pragma", "no-cache");
            headers.add("Expires", "0");
            headers.add("Content-Language", "UTF-8");
            //最终这句，让文件内容以流的形式输出
            return ResponseEntity.ok().headers(headers).contentLength(testBytes.length)
                .contentType(MediaType.parseMediaType("application/octet-stream")).body(new InputStreamResource(in));
        } catch (IOException e) {
            log.info("downfile is error" + e.getMessage());
        }
        log.info("file is null" + fileName);
        return null;
    }

2.下载xx文件夹

“下载文件夹及内部文件” 执行流程说明：
    1.初始化header请求头信息，格式以xx.zip输出文件夹，调用down2()
    2.构建hdfs连接，初始化Configuration
    3.调用迭代器compress,传入参数（文件夹整体路径 + ZipOutputStream实例 + FileSystem实例）
    4.迭代器执行思路：
            遍历对应子目录：1）如果为文件夹，zip写入一个文件进入点（路径末尾单词 + “/”）
                          2）如果为文件，zip写入文件（目录文件的整体路径）
                          
----------------------------------------------------------------------------------------                      
******注意：容易出错2行代码：******
压缩文件：zipOutputStream.putNextEntry(new ZipEntry(name.substring(1)));
压缩文件夹：zipOutputStream.putNextEntry(new ZipEntry(fileStatulist[i].getPath().getName() + "/"));
**name属性用于zip创建文件，fileStatulist[i].getPath().getName()用于zip创建文件夹**
-----------------------------------------------------------------------------------------
举例说明：
    假设文件夹spark-warehouse路径下有2文件夹data1和data2，文件夹下各一个a.txt文本文件
    第一步：获取路径“C:/Users/liudz/Desktop/spark-warehouse”下的目录，也就是（C:/Users/liudz/Desktop/spark-warehouse/data1、C:/Users/liudz/Desktop/spark-warehouse/data2）
    lastName=spark-warehouse
    name=/spark-warehouse/data1
    判断“C:/Users/liudz/Desktop/spark-warehouse/data1”为目录，zip写入“data1/”文件夹
    第二步：获取路径“C:/Users/liudz/Desktop/spark-warehouse/data1”下的目录，也就是（C:/Users/liudz/Desktop/spark-warehouse/data1/a.txt）
    lastName=data1
    name=/data1/a.txt
    判断“C:/Users/liudz/Desktop/spark-warehouse/data1/a.txt”为文件，zip写入“data1/a。txt”文件
    。
    。
    。

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import util.ExportUtil;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
/**
     *  下载文件夹
     * @param businessId 业务ID
     * @author liudz
     * @date 2020/6/9
     * @return 执行结果
     **/
    @RequestMapping(value = "/downloadFolder", method = RequestMethod.GET)
    public ResponseEntity<byte[]> downloadFolder(Long businessId) throws IOException {
        ResponseEntity<byte[]> response = null;
        HttpHeaders headers = new HttpHeaders();
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Content-Disposition", "attachment; filename=spark-warehouse.zip");
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");
        headers.add("Content-Language", "UTF-8");
        ByteArrayOutputStream zos =
                (ByteArrayOutputStream) hdfsClientService.down2("hdfs://172.16.1.9:8020/spark/spark-warehouse");
        byte[] out = zos.toByteArray();
        zos.close();
        response = new ResponseEntity<>(out, headers, HttpStatus.OK);

        return response;
    }

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

import lombok.extern.slf4j.Slf4j;

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;
import org.springframework.stereotype.Service;
/**
     * 多文件
     * 
     * @param cloudPath
     *            cloudPath
     * @author liudz
     * @date 2020/6/8
     * @return 执行结果
     **/
    public OutputStream down2(String cloudPath) {
        // 1获取对象
        ByteArrayOutputStream out = null;
        try {
            Configuration conf = new Configuration();
            FileSystem fs = FileSystem.get(new URI("hdfs://172.16.1.9:8020"), conf);
            out = new ByteArrayOutputStream();
            ZipOutputStream zos = new ZipOutputStream(out);
            compress(cloudPath, zos, fs);
            zos.close();
        } catch (IOException e) {
            log.info("----error:{}----" + e.getMessage());
        } catch (URISyntaxException e) {
            log.info("----error:{}----" + e.getMessage());
        }
        return out;
    }

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

import lombok.extern.slf4j.Slf4j;

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;
import org.springframework.stereotype.Service;
/**
     * compress
     * 
     * @param baseDir
     *            baseDir
     * @param zipOutputStream
     *            zipOutputStream
     * @param fs
     *            fs
     * @author liudz
     * @date 2020/6/8
     **/
    public void compress(String baseDir, ZipOutputStream zipOutputStream, FileSystem fs) throws IOException {

        try {
            FileStatus[] fileStatulist = fs.listStatus(new Path(baseDir));
            log.info("basedir = " + baseDir);
            String[] strs = baseDir.split("/");
            //lastName代表路径最后的单词
            String lastName = strs[strs.length - 1];

            for (int i = 0; i < fileStatulist.length; i++) {

                String name = fileStatulist[i].getPath().toString();
                name = name.substring(name.indexOf("/" + lastName));

                if (fileStatulist[i].isFile()) {
                    Path path = fileStatulist[i].getPath();
                    FSDataInputStream inputStream = fs.open(path);
                    zipOutputStream.putNextEntry(new ZipEntry(name.substring(1)));
                    IOUtils.copyBytes(inputStream, zipOutputStream, Integer.parseInt("1024"));
                    inputStream.close();
                } else {
                    zipOutputStream.putNextEntry(new ZipEntry(fileStatulist[i].getPath().getName() + "/"));
                    log.info("fileStatulist[i].getPath().toString() = " + fileStatulist[i].getPath().toString());
                    compress(fileStatulist[i].getPath().toString(), zipOutputStream, fs);
                }
            }
        } catch (IOException e) {
            log.info("----error:{}----" + e.getMessage());
        }
    }

重要信息

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