1、添加以下依賴
<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相關的基本操作:
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相關的基本操作
*
* @author adminstrator
* @since 1.0.0
*/
public class HdfsService {
private Logger logger = LoggerFactory.getLogger(HdfsService.class);
private Configuration conf = null;
/**
* 默認的HDFS路徑,比如:hdfs://192.168.197.130:9000
*/
private String defaultHdfsUri;
public HdfsService(Configuration conf,String defaultHdfsUri) {
this.conf = conf;
this.defaultHdfsUri = defaultHdfsUri;
}
/**
* 獲取HDFS文件系統
* @return org.apache.hadoop.fs.FileSystem
*/
private FileSystem getFileSystem() throws IOException {
return FileSystem.get(conf);
}
/**
* 創建HDFS目錄
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,比如:/testDir
* @return boolean 是否創建成功
*/
public boolean mkdir(String path){
//如果目錄已經存在,則直接返回
if(checkExists(path)){
return true;
}else{
FileSystem fileSystem = null;
try {
fileSystem = getFileSystem();
//最終的HDFS文件目錄
String hdfsPath = generateHdfsPath(path);
//創建目錄
return fileSystem.mkdirs(new Path(hdfsPath));
} catch (IOException e) {
logger.error(MessageFormat.format("創建HDFS目錄失敗,path:{0}",path),e);
return false;
}finally {
close(fileSystem);
}
}
}
/**
* 上傳文件至HDFS
* @author adminstrator
* @since 1.0.0
* @param srcFile 本地文件路徑,比如:D:/test.txt
* @param dstPath HDFS的相對目錄路徑,比如:/testDir
*/
public void uploadFileToHdfs(String srcFile, String dstPath){
this.uploadFileToHdfs(false, true, srcFile, dstPath);
}
/**
* 上傳文件至HDFS
* @author adminstrator
* @since 1.0.0
* @param delSrc 是否刪除本地文件
* @param overwrite 是否覆蓋HDFS上面的文件
* @param srcFile 本地文件路徑,比如:D:/test.txt
* @param dstPath HDFS的相對目錄路徑,比如:/testDir
*/
public void uploadFileToHdfs(boolean delSrc, boolean overwrite, String srcFile, String dstPath){
//源文件路徑
Path localSrcPath = new Path(srcFile);
//目標文件路徑
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("上傳文件至HDFS失敗,srcFile:{0},dstPath:{1}",srcFile,dstPath),e);
}finally {
close(fileSystem);
}
}
/**
* 判斷文件或者目錄是否在HDFS上面存在
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,比如:/testDir、/testDir/a.txt
* @return boolean
*/
public boolean checkExists(String path){
FileSystem fileSystem = null;
try {
fileSystem = getFileSystem();
//最終的HDFS文件目錄
String hdfsPath = generateHdfsPath(path);
//創建目錄
return fileSystem.exists(new Path(hdfsPath));
} catch (IOException e) {
logger.error(MessageFormat.format("'判斷文件或者目錄是否在HDFS上面存在'失敗,path:{0}",path),e);
return false;
}finally {
close(fileSystem);
}
}
/**
* 獲取HDFS上面的某個路徑下面的所有文件或目錄(不包含子目錄)信息
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,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){
//返回數據
List<Map<String,Object>> result = new ArrayList<>();
//如果目錄已經存在,則繼續操作
if(checkExists(path)){
FileSystem fileSystem = null;
try {
fileSystem = getFileSystem();
//最終的HDFS文件目錄
String hdfsPath = generateHdfsPath(path);
FileStatus[] statuses;
//根據Path過濾器查詢
if(pathFilter != null){
statuses = fileSystem.listStatus(new Path(hdfsPath),pathFilter);
}else{
statuses = fileSystem.listStatus(new Path(hdfsPath));
}
if(statuses != null){
for(FileStatus status : statuses){
//每個文件的屬性
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("獲取HDFS上面的某個路徑下面的所有文件失敗,path:{0}",path),e);
}finally {
close(fileSystem);
}
}
return result;
}
/**
* 從HDFS下載文件至本地
* @author adminstrator
* @since 1.0.0
* @param srcFile HDFS的相對目錄路徑,比如:/testDir/a.txt
* @param dstFile 下載之後本地文件路徑(如果本地文件目錄不存在,則會自動創建),比如:D:/test.txt
*/
public void downloadFileFromHdfs(String srcFile, String dstFile){
//HDFS文件路徑
Path hdfsSrcPath = new Path(generateHdfsPath(srcFile));
//下載之後本地文件路徑
Path localDstPath = new Path(dstFile);
FileSystem fileSystem = null;
try {
fileSystem = getFileSystem();
fileSystem.copyToLocalFile(hdfsSrcPath,localDstPath);
} catch (IOException e) {
logger.error(MessageFormat.format("從HDFS下載文件至本地失敗,srcFile:{0},dstFile:{1}",srcFile,dstFile),e);
}finally {
close(fileSystem);
}
}
/**
* 打開HDFS上面的文件並返回 InputStream
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,比如:/testDir/c.txt
* @return FSDataInputStream
*/
public FSDataInputStream open(String path){
//HDFS文件路徑
Path hdfsPath = new Path(generateHdfsPath(path));
FileSystem fileSystem = null;
try {
fileSystem = getFileSystem();
return fileSystem.open(hdfsPath);
} catch (IOException e) {
logger.error(MessageFormat.format("打開HDFS上面的文件失敗,path:{0}",path),e);
}
return null;
}
/**
* 打開HDFS上面的文件並返回byte數組,方便Web端下載文件
* <p>new ResponseEntity<byte[]>(byte數組, 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的相對目錄路徑,比如:/testDir/b.txt
* @return FSDataInputStream
*/
public byte[] openWithBytes(String path){
//HDFS文件路徑
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("打開HDFS上面的文件失敗,path:{0}",path),e);
}finally {
if(inputStream != null){
try {
inputStream.close();
} catch (IOException e) {
// ignore
}
}
}
return null;
}
/**
* 打開HDFS上面的文件並返回String字符串
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,比如:/testDir/b.txt
* @return FSDataInputStream
*/
public String openWithString(String path){
//HDFS文件路徑
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("打開HDFS上面的文件失敗,path:{0}",path),e);
}finally {
if(inputStream != null){
try {
inputStream.close();
} catch (IOException e) {
// ignore
}
}
}
return null;
}
/**
* 打開HDFS上面的文件並轉換爲Java對象(需要HDFS上門的文件內容爲JSON字符串)
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,比如:/testDir/c.txt
* @return FSDataInputStream
*/
public <T extends Object> T openWithObject(String path, Class<T> clazz){
//1、獲得文件的json字符串
String jsonStr = this.openWithString(path);
//2、使用com.alibaba.fastjson.JSON將json字符串轉化爲Java對象並返回
return JSON.parseObject(jsonStr, clazz);
}
/**
* 重命名
* @author adminstrator
* @since 1.0.0
* @param srcFile 重命名之前的HDFS的相對目錄路徑,比如:/testDir/b.txt
* @param dstFile 重命名之後的HDFS的相對目錄路徑,比如:/testDir/b_new.txt
*/
public boolean rename(String srcFile, String dstFile) {
//HDFS文件路徑
Path srcFilePath = new Path(generateHdfsPath(srcFile));
//下載之後本地文件路徑
Path dstFilePath = new Path(dstFile);
FileSystem fileSystem = null;
try {
fileSystem = getFileSystem();
return fileSystem.rename(srcFilePath,dstFilePath);
} catch (IOException e) {
logger.error(MessageFormat.format("重命名失敗,srcFile:{0},dstFile:{1}",srcFile,dstFile),e);
}finally {
close(fileSystem);
}
return false;
}
/**
* 刪除HDFS文件或目錄
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,比如:/testDir/c.txt
* @return boolean
*/
public boolean delete(String path) {
//HDFS文件路徑
Path hdfsPath = new Path(generateHdfsPath(path));
FileSystem fileSystem = null;
try {
fileSystem = getFileSystem();
return fileSystem.delete(hdfsPath,true);
} catch (IOException e) {
logger.error(MessageFormat.format("刪除HDFS文件或目錄失敗,path:{0}",path),e);
}finally {
close(fileSystem);
}
return false;
}
/**
* 獲取某個文件在HDFS集羣的位置
* @author adminstrator
* @since 1.0.0
* @param path HDFS的相對目錄路徑,比如:/testDir/a.txt
* @return org.apache.hadoop.fs.BlockLocation[]
*/
public BlockLocation[] getFileBlockLocations(String path) {
//HDFS文件路徑
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("獲取某個文件在HDFS集羣的位置失敗,path:{0}",path),e);
}finally {
close(fileSystem);
}
return null;
}
/**
* 將相對路徑轉化爲HDFS文件路徑
* @author adminstrator
* @since 1.0.0
* @param dstPath 相對路徑,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相關配置
*
* @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、測試相關功能
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;
/**
* 測試HDFS的基本操作
*
* @author adminstrator
* @since 1.0.0
*/
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
@WebAppConfiguration
public class TestHdfs {
@Autowired
private HdfsService hdfsService;
/**
* 測試創建HDFS目錄
*/
@Test
public void testMkdir(){
boolean result1 = hdfsService.mkdir("/testDir");
System.out.println("創建結果:" + result1);
boolean result2 = hdfsService.mkdir("/testDir/subDir");
System.out.println("創建結果:" + result2);
}
/**
* 測試上傳文件
*/
@Test
public void testUploadFile(){
//測試上傳三個文件
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");
}
/**
* 測試列出某個目錄下面的文件
*/
@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();
});
}
/**
* 測試下載文件
*/
@Test
public void testDownloadFile(){
hdfsService.downloadFileFromHdfs("/testDir/a.txt","C:/Users/yanglei/Desktop/test111.txt");
}
/**
* 測試打開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();
}
/**
* 測試打開HDFS上面的文件,並轉化爲Java對象
*/
@Test
public void testOpenWithObject() throws IOException {
SysUserEntity user = hdfsService.openWithObject("/testDir/b.txt", SysUserEntity.class);
System.out.println(user);
}
/**
* 測試重命名
*/
@Test
public void testRename(){
hdfsService.rename("/testDir/b.txt","/testDir/b_new.txt");
//再次遍歷
testListFiles();
}
/**
* 測試刪除文件
*/
@Test
public void testDelete(){
hdfsService.delete("/testDir/b_new.txt");
//再次遍歷
testListFiles();
}
/**
* 測試獲取某個文件在HDFS集羣的位置
*/
@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集羣搭建及相關配置:HDFS3.x集羣配置
可能遇到的問題及解決辦法:Java API操作Hadoop可能會遇到的問題以及解決辦法