Spring Boot项目中使用HDFS3.x

1、添加以下依赖

<dependency>
  <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-common</artifactId>
    <version>3.1.0</version>
</dependency>
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-hdfs</artifactId>
    <version>3.1.0</version>
</dependency>
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-mapreduce-client-core</artifactId>
    <version>3.1.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>27.0.1-jre</version>
</dependency>
<dependency>
	<groupId>com.alibaba</groupId>
	<artifactId>fastjson</artifactId>
	<version>1.2.44</version>
</dependency>

2、HDFS相关的基本操作：

import com.alibaba.fastjson.JSON;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.BlockLocation;
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.fs.PathFilter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.nio.charset.Charset;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * HDFS相关的基本操作
 *
 * @author adminstrator
 * @since 1.0.0
 */
public class HdfsService {

    private Logger logger = LoggerFactory.getLogger(HdfsService.class);
    private Configuration conf = null;

    /**
     * 默认的HDFS路径，比如：hdfs://192.168.197.130:9000
     */
    private String defaultHdfsUri;

    public HdfsService(Configuration conf,String defaultHdfsUri) {
        this.conf = conf;
        this.defaultHdfsUri = defaultHdfsUri;
    }

    /**
     * 获取HDFS文件系统
     * @return org.apache.hadoop.fs.FileSystem
     */
    private FileSystem getFileSystem() throws IOException {
        return FileSystem.get(conf);
    }

    /**
     * 创建HDFS目录
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir
     * @return boolean 是否创建成功
     */
    public boolean mkdir(String path){
        //如果目录已经存在，则直接返回
        if(checkExists(path)){
            return true;
        }else{
            FileSystem fileSystem = null;

            try {
                fileSystem = getFileSystem();

                //最终的HDFS文件目录
                String hdfsPath = generateHdfsPath(path);
                //创建目录
                return fileSystem.mkdirs(new Path(hdfsPath));
            } catch (IOException e) {
                logger.error(MessageFormat.format("创建HDFS目录失败，path:{0}",path),e);
                return false;
            }finally {
                close(fileSystem);
            }
        }
    }

    /**
     * 上传文件至HDFS
     * @author adminstrator
     * @since 1.0.0
     * @param srcFile 本地文件路径，比如：D:/test.txt
     * @param dstPath HDFS的相对目录路径，比如：/testDir
     */
    public void uploadFileToHdfs(String srcFile, String dstPath){
        this.uploadFileToHdfs(false, true, srcFile, dstPath);
    }

    /**
     * 上传文件至HDFS
     * @author adminstrator
     * @since 1.0.0
     * @param delSrc 是否删除本地文件
     * @param overwrite 是否覆盖HDFS上面的文件
     * @param srcFile 本地文件路径，比如：D:/test.txt
     * @param dstPath HDFS的相对目录路径，比如：/testDir
     */
    public void uploadFileToHdfs(boolean delSrc, boolean overwrite, String srcFile, String dstPath){
        //源文件路径
        Path localSrcPath = new Path(srcFile);
        //目标文件路径
        Path hdfsDstPath = new Path(generateHdfsPath(dstPath));

        FileSystem fileSystem = null;
        try {
            fileSystem = getFileSystem();

            fileSystem.copyFromLocalFile(delSrc,overwrite,localSrcPath,hdfsDstPath);
        } catch (IOException e) {
            logger.error(MessageFormat.format("上传文件至HDFS失败，srcFile:{0},dstPath:{1}",srcFile,dstPath),e);
        }finally {
            close(fileSystem);
        }
    }

    /**
     * 判断文件或者目录是否在HDFS上面存在
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir、/testDir/a.txt
     * @return boolean
     */
    public boolean checkExists(String path){
        FileSystem fileSystem = null;
        try {
            fileSystem = getFileSystem();

            //最终的HDFS文件目录
            String hdfsPath = generateHdfsPath(path);

            //创建目录
            return fileSystem.exists(new Path(hdfsPath));
        } catch (IOException e) {
            logger.error(MessageFormat.format("'判断文件或者目录是否在HDFS上面存在'失败，path:{0}",path),e);
            return false;
        }finally {
            close(fileSystem);
        }
    }

    /**
     * 获取HDFS上面的某个路径下面的所有文件或目录（不包含子目录）信息
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir
     * @return java.util.List<java.util.Map<java.lang.String,java.lang.Object>>
     */
    public List<Map<String,Object>> listFiles(String path, PathFilter pathFilter){
        //返回数据
        List<Map<String,Object>> result = new ArrayList<>();

        //如果目录已经存在，则继续操作
        if(checkExists(path)){
            FileSystem fileSystem = null;

            try {
                fileSystem = getFileSystem();

                //最终的HDFS文件目录
                String hdfsPath = generateHdfsPath(path);

                FileStatus[] statuses;
                //根据Path过滤器查询
                if(pathFilter != null){
                    statuses = fileSystem.listStatus(new Path(hdfsPath),pathFilter);
                }else{
                    statuses = fileSystem.listStatus(new Path(hdfsPath));
                }

                if(statuses != null){
                    for(FileStatus status : statuses){
                        //每个文件的属性
                        Map<String,Object> fileMap = new HashMap<>(2);

                        fileMap.put("path",status.getPath().toString());
                        fileMap.put("isDir",status.isDirectory());

                        result.add(fileMap);
                    }
                }
            } catch (IOException e) {
                logger.error(MessageFormat.format("获取HDFS上面的某个路径下面的所有文件失败，path:{0}",path),e);
            }finally {
                close(fileSystem);
            }
        }

        return result;
    }


    /**
     * 从HDFS下载文件至本地
     * @author adminstrator
     * @since 1.0.0
     * @param srcFile HDFS的相对目录路径，比如：/testDir/a.txt
     * @param dstFile 下载之后本地文件路径（如果本地文件目录不存在，则会自动创建），比如：D:/test.txt
     */
    public void downloadFileFromHdfs(String srcFile, String dstFile){
        //HDFS文件路径
        Path hdfsSrcPath = new Path(generateHdfsPath(srcFile));
        //下载之后本地文件路径
        Path localDstPath = new Path(dstFile);

        FileSystem fileSystem = null;
        try {
            fileSystem = getFileSystem();

            fileSystem.copyToLocalFile(hdfsSrcPath,localDstPath);
        } catch (IOException e) {
            logger.error(MessageFormat.format("从HDFS下载文件至本地失败，srcFile:{0},dstFile:{1}",srcFile,dstFile),e);
        }finally {
            close(fileSystem);
        }
    }

    /**
     * 打开HDFS上面的文件并返回 InputStream
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir/c.txt
     * @return FSDataInputStream
     */
    public FSDataInputStream open(String path){
        //HDFS文件路径
        Path hdfsPath = new Path(generateHdfsPath(path));

        FileSystem fileSystem = null;
        try {
            fileSystem = getFileSystem();

            return fileSystem.open(hdfsPath);
        } catch (IOException e) {
            logger.error(MessageFormat.format("打开HDFS上面的文件失败，path:{0}",path),e);
        }

        return null;
    }

    /**
     * 打开HDFS上面的文件并返回byte数组，方便Web端下载文件
     * <p>new ResponseEntity<byte[]>(byte数组, headers, HttpStatus.CREATED);</p>
     * <p>或者：new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(templateFile), headers, HttpStatus.CREATED);</p>
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir/b.txt
     * @return FSDataInputStream
     */
    public byte[] openWithBytes(String path){
        //HDFS文件路径
        Path hdfsPath = new Path(generateHdfsPath(path));

        FileSystem fileSystem = null;
        FSDataInputStream inputStream = null;
        try {
            fileSystem = getFileSystem();
            inputStream = fileSystem.open(hdfsPath);

            return IOUtils.toByteArray(inputStream);
        } catch (IOException e) {
            logger.error(MessageFormat.format("打开HDFS上面的文件失败，path:{0}",path),e);
        }finally {
            if(inputStream != null){
                try {
                    inputStream.close();
                } catch (IOException e) {
                    // ignore
                }
            }
        }

        return null;
    }

    /**
     * 打开HDFS上面的文件并返回String字符串
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir/b.txt
     * @return FSDataInputStream
     */
    public String openWithString(String path){
        //HDFS文件路径
        Path hdfsPath = new Path(generateHdfsPath(path));

        FileSystem fileSystem = null;
        FSDataInputStream inputStream = null;
        try {
            fileSystem = getFileSystem();
            inputStream = fileSystem.open(hdfsPath);

            return IOUtils.toString(inputStream, Charset.forName("UTF-8"));
        } catch (IOException e) {
            logger.error(MessageFormat.format("打开HDFS上面的文件失败，path:{0}",path),e);
        }finally {
            if(inputStream != null){
                try {
                    inputStream.close();
                } catch (IOException e) {
                    // ignore
                }
            }
        }

        return null;
    }

    /**
     * 打开HDFS上面的文件并转换为Java对象（需要HDFS上门的文件内容为JSON字符串）
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir/c.txt
     * @return FSDataInputStream
     */
    public <T extends Object> T openWithObject(String path, Class<T> clazz){
        //1、获得文件的json字符串
        String jsonStr = this.openWithString(path);

        //2、使用com.alibaba.fastjson.JSON将json字符串转化为Java对象并返回
        return JSON.parseObject(jsonStr, clazz);
    }

    /**
     * 重命名
     * @author adminstrator
     * @since 1.0.0
     * @param srcFile 重命名之前的HDFS的相对目录路径，比如：/testDir/b.txt
     * @param dstFile 重命名之后的HDFS的相对目录路径，比如：/testDir/b_new.txt
     */
    public boolean rename(String srcFile, String dstFile) {
        //HDFS文件路径
        Path srcFilePath = new Path(generateHdfsPath(srcFile));
        //下载之后本地文件路径
        Path dstFilePath = new Path(dstFile);

        FileSystem fileSystem = null;
        try {
            fileSystem = getFileSystem();

            return fileSystem.rename(srcFilePath,dstFilePath);
        } catch (IOException e) {
            logger.error(MessageFormat.format("重命名失败，srcFile:{0},dstFile:{1}",srcFile,dstFile),e);
        }finally {
            close(fileSystem);
        }

        return false;
    }

    /**
     * 删除HDFS文件或目录
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir/c.txt
     * @return boolean
     */
    public boolean delete(String path) {
        //HDFS文件路径
        Path hdfsPath = new Path(generateHdfsPath(path));

        FileSystem fileSystem = null;
        try {
            fileSystem = getFileSystem();

            return fileSystem.delete(hdfsPath,true);
        } catch (IOException e) {
            logger.error(MessageFormat.format("删除HDFS文件或目录失败，path:{0}",path),e);
        }finally {
            close(fileSystem);
        }

        return false;
    }

    /**
     * 获取某个文件在HDFS集群的位置
     * @author adminstrator
     * @since 1.0.0
     * @param path HDFS的相对目录路径，比如：/testDir/a.txt
     * @return org.apache.hadoop.fs.BlockLocation[]
     */
    public BlockLocation[] getFileBlockLocations(String path) {
        //HDFS文件路径
        Path hdfsPath = new Path(generateHdfsPath(path));

        FileSystem fileSystem = null;
        try {
            fileSystem = getFileSystem();
            FileStatus fileStatus = fileSystem.getFileStatus(hdfsPath);

            return fileSystem.getFileBlockLocations(fileStatus, 0, fileStatus.getLen());
        } catch (IOException e) {
            logger.error(MessageFormat.format("获取某个文件在HDFS集群的位置失败，path:{0}",path),e);
        }finally {
            close(fileSystem);
        }

        return null;
    }


    /**
     * 将相对路径转化为HDFS文件路径
     * @author adminstrator
     * @since 1.0.0
     * @param dstPath 相对路径，比如：/data
     * @return java.lang.String
     */
    private String generateHdfsPath(String dstPath){
        String hdfsPath = defaultHdfsUri;
        if(dstPath.startsWith("/")){
            hdfsPath += dstPath;
        }else{
            hdfsPath = hdfsPath + "/" + dstPath;
        }

        return hdfsPath;
    }

    /**
     * close方法
     */
    private void close(FileSystem fileSystem){
        if(fileSystem != null){
            try {
                fileSystem.close();
            } catch (IOException e) {
                logger.error(e.getMessage());
            }
        }
    }
}

3、添加HDFS配置信息：

import io.renren.service.HdfsService;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * HDFS相关配置
 *
 * @author adminstrator
 * @since 1.0.0
 */
@Configuration
public class HdfsConfig {
    private String defaultHdfsUri = "hdfs://192.168.0.9:9000";

    @Bean
    public HdfsService getHbaseService(){
        org.apache.hadoop.conf.Configuration conf = new org.apache.hadoop.conf.Configuration();
        conf.set("fs.defaultFS",defaultHdfsUri);
        return new HdfsService(conf,defaultHdfsUri);
    }
}

4、测试相关功能

import io.renren.entity.SysUserEntity;
import org.apache.hadoop.fs.BlockLocation;
import org.apache.hadoop.fs.FSDataInputStream;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.WebAppConfiguration;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;
import java.util.Map;

/**
 * 测试HDFS的基本操作
 *
 * @author adminstrator
 * @since 1.0.0
 */
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
@WebAppConfiguration
public class TestHdfs {

    @Autowired
    private HdfsService hdfsService;


    /**
     * 测试创建HDFS目录
     */
    @Test
    public void testMkdir(){
        boolean result1 = hdfsService.mkdir("/testDir");
        System.out.println("创建结果：" + result1);

        boolean result2 = hdfsService.mkdir("/testDir/subDir");
        System.out.println("创建结果：" + result2);
    }

    /**
     * 测试上传文件
     */
    @Test
    public void testUploadFile(){
        //测试上传三个文件
        hdfsService.uploadFileToHdfs("C:/Users/yanglei/Desktop/a.txt","/testDir");
        hdfsService.uploadFileToHdfs("C:/Users/yanglei/Desktop/b.txt","/testDir");

        hdfsService.uploadFileToHdfs("C:/Users/yanglei/Desktop/c.txt","/testDir/subDir");
    }

    /**
     * 测试列出某个目录下面的文件
     */
    @Test
    public void testListFiles(){
        List<Map<String,Object>> result = hdfsService.listFiles("/testDir",null);

        result.forEach(fileMap -> {
            fileMap.forEach((key,value) -> {
                System.out.println(key + "--" + value);
            });
            System.out.println();
        });
    }

    /**
     * 测试下载文件
     */
    @Test
    public void testDownloadFile(){
        hdfsService.downloadFileFromHdfs("/testDir/a.txt","C:/Users/yanglei/Desktop/test111.txt");
    }

    /**
     * 测试打开HDFS上面的文件
     */
    @Test
    public void testOpen() throws IOException {
        FSDataInputStream inputStream = hdfsService.open("/testDir/a.txt");

        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        String line = null;
        while((line = reader.readLine())!=null){
            System.out.println(line);
        }

        reader.close();
    }

    /**
     * 测试打开HDFS上面的文件，并转化为Java对象
     */
    @Test
    public void testOpenWithObject() throws IOException {
        SysUserEntity user = hdfsService.openWithObject("/testDir/b.txt", SysUserEntity.class);
        System.out.println(user);
    }

    /**
     * 测试重命名
     */
    @Test
    public void testRename(){
        hdfsService.rename("/testDir/b.txt","/testDir/b_new.txt");

        //再次遍历
        testListFiles();
    }

    /**
     * 测试删除文件
     */
    @Test
    public void testDelete(){
        hdfsService.delete("/testDir/b_new.txt");

        //再次遍历
        testListFiles();
    }

    /**
     * 测试获取某个文件在HDFS集群的位置
     */
    @Test
    public void testGetFileBlockLocations() throws IOException {
        BlockLocation[] locations = hdfsService.getFileBlockLocations("/testDir/a.txt");

        if(locations != null && locations.length > 0){
            for(BlockLocation location : locations){
                System.out.println(location.getHosts()[0]);
            }
        }
    }
}

HDFS集群搭建及相关配置：HDFS3.x集群配置
可能遇到的问题及解决办法：Java API操作Hadoop可能会遇到的问题以及解决办法