版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/qq_15014327/article/details/83033267
一.开发环境搭建
使用IDE工具(Eclipse或Idea)创建一个Maven工程，导入Hadoop依赖包。
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>cn.tl</groupId>
<artifactId>Hdp-core</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>Hdp-core</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<!-- 首先配置仓库的服务器位置,首选阿里云，也可以配置镜像方式，效果雷同 -->
<repositories>
<repository>
<id>nexus-aliyun</id>
<name>Nexus aliyun</name>
<url>http://maven.aliyun.com/nexus/content/groups/public</url>
</repository>
</repositories>
<dependencies>
<!-- 引入hadoop-cli-2.7.4依赖 -->
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-client</artifactId>
<version>2.7.4</version>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<finalName>Hdp-core</finalName>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>assembly</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>二.代码
package cn.tl.hdfs;
/**
* Hdfs Java工具类
* @author lw
*/
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import org.apache.commons.lang.StringUtils;
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;
import org.apache.log4j.Logger;
public class HdfsUtil {
// 日志
public static Logger logger = Logger.getLogger(HdfsUtil.class);
// 集群环境配置
public static Configuration conf = new Configuration();
/**
* 在hdfs上创建目录
*
* @param 创建目录
* @return
* @throws Exception
*/
public static boolean mkdir(String src) throws Exception {
if (StringUtils.isEmpty(src) || src.trim().length() == 0) {
logger.error("要创建的目录不能为空!");
return false;
}
FileSystem fs = FileSystem.get(conf);
Path path = new Path(src);
boolean isSuccess = fs.mkdirs(path);
return isSuccess;
}
/**
* 在hdfs上删除目录
*
* @param 要刪除的目录
* @param 是否递归
* @return
* @throws Exception
*/
public static boolean rmdir(String src, boolean recursive) throws Exception {
if (StringUtils.isEmpty(src) || src.trim().length() == 0) {
logger.error("要删除的目录不能为空!");
return false;
}
FileSystem fs = FileSystem.get(conf);
Path path = new Path(src);
boolean isSuccess = fs.delete(path, recursive);
return isSuccess;
}
/**
* 在hdfs上删除文件
*
* @param 要刪除的文件
* @return
* @throws Exception
*/
public static boolean rmFile(String src) throws Exception {
if (StringUtils.isEmpty(src) || src.trim().length() == 0) {
logger.error("文件名不能为空!");
return false;
}
FileSystem fs = FileSystem.get(conf);
Path path = new Path(src);
if (fs.isDirectory(path)) {
logger.error(src + ":是一个目录，请检查传入的参数!");
return false;
}
boolean isSuccess = fs.delete(path);
return isSuccess;
}
/**
* 向hdfs上传文件
*
* @param 是否删除源文件
* @param 是否覆盖hdfs文件
* @param 源路径
* @param 目标路径
* @throws Exception
*/
public static void copyFromLocal(boolean delSrc, boolean overwrite, String src, String dst) throws Exception {
if (StringUtils.isEmpty(src) || src.trim().length() == 0 || StringUtils.isEmpty(dst)
|| dst.trim().length() == 0) {
logger.error("源文件名或目标文件名不能为空!");
return;
}
FileSystem fs = FileSystem.get(conf);
Path srcPath = new Path(src);
Path dstPath = new Path(dst);
fs.copyFromLocalFile(delSrc, overwrite, srcPath, dstPath);
}
/**
* 从hdfs下载文件
*
* @param 是否删除源文件
* @param 源路径
* @param 目标路径
* @throws Exception
*/
public static void copyToLocal(boolean delSrc, String src, String dst) throws Exception {
if (StringUtils.isEmpty(src) || src.trim().length() == 0 || StringUtils.isEmpty(dst)
|| dst.trim().length() == 0) {
logger.error("源文件名或目标文件名不能为空!");
return;
}
FileSystem fs = FileSystem.get(conf);
Path srcPath = new Path(src);
Path dstPath = new Path(dst);
fs.copyToLocalFile(delSrc, srcPath, dstPath);
}
/**
* 列出该目录的文件
*
* @param 要查看的目录
* @return
* @throws Exception
*/
public static FileStatus[] listFileStatus(String src) throws Exception {
if (StringUtils.isEmpty(src) || src.trim().length() == 0) {
logger.error("目录不能为空!");
return null;
}
FileSystem fs = FileSystem.get(conf);
Path path = new Path(src);
return fs.listStatus(path);
}
/**
* 读文件
*
* @param src
* @return
* @throws Exception
*/
public static byte[] readFile(String src) throws Exception {
if (StringUtils.isEmpty(src) || src.trim().length() == 0) {
logger.error("文件名不能为空!");
return null;
}
FileSystem fs = FileSystem.get(conf);
Path path = new Path(src);
FSDataInputStream in = fs.open(path);
ByteArrayOutputStream out = new ByteArrayOutputStream();
byte[] b = new byte[1024];
int len = 0;
while ((len = in.read(b)) != -1) {
out.write(b, 0, len);
}
in.close();
out.close();
return out.toByteArray();
}
/**
* 写文件
*
* @param src
* @param hdfs
* @param overwrite
* @return
*/
public static boolean writeFile(String src, String hdfs, boolean overwrite) {
FSDataOutputStream out = null;
try {
if (StringUtils.isEmpty(hdfs) || hdfs.trim().length() == 0) {
logger.error("hdfs文件名不能为空!");
return false;
}
if (StringUtils.isEmpty(src) || src.trim().length() == 0) {
logger.error("src文件名不能为空!");
return false;
}
FileSystem fs = FileSystem.get(conf);
Path path = new Path(hdfs);
out = fs.create(path, overwrite);
byte[] b = readFile(src);
out.write(b);
return true;
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return false;
}
}