本篇博文给大家介绍的是进行JavaAPI操作前的准备工作

一. 电脑安装配置Hadoop

1. 将下载的jar包放到非中文路径

博主路径为：D:\hadoop\hadoop-2.7.2

2. 配置HADOOP_HOME环境变量

3. 配置Path环境变量

4. 测试是否成功

输入：winutils

如果出现上述界面，即代表成功，否则为失败

二. maven

1. 此步可省略，一般用自带的即可

2. 创建一个Maven工程

1. 创建过程

2. 添加依赖
在pom.xml中添加如下内容:

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.8.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-hdfs</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>jdk.tools</groupId>
            <artifactId>jdk.tools</artifactId>
            <version>1.8</version>
            <scope>system</scope>
            <systemPath>D:/java/jdk-1.8.0/lib/tools.jar</systemPath>
        </dependency>
    </dependencies>

3. 添加完毕之后,右上角检查没有报错说明我们的maven项目的jar包配置成功!

4. 如果Eclipse/Idea打印不出日志，在控制台上只显示：

1.log4j:WARN No appenders could be found for logger (org.apache.hadoop.util.Shell).  
2.log4j:WARN Please initialize the log4j system properly.  
3.log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

需要在项目的src/main/resources目录下，新建一个文件，命名为“log4j.properties”，在文件中填入

log4j.rootLogger=INFO, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

三. 创建包和类

1. 创建

2. 输入测试代码

package com.buwenbuhuo.hdfs;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.junit.Test;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

/**
 * @author buwenbuhuo
 * @create 2020-04-22 16:45
 * com.buwenbuhuo.hdfs - the name of the target package where the new class or interface will be created.
 * hdfs0422 - the name of the current project.
 */
public class HDFSClient {
        @Test
        public void testMkdirs() throws IOException, InterruptedException, URISyntaxException {

            // 1 获取文件系统
            Configuration configuration = new Configuration();
            // 配置在集群上运行
            FileSystem fs = FileSystem.get(URI.create("hdfs://hadoop001:9000"), configuration, "bigdata");

            // 2 创建目录
            fs.mkdirs(new Path("/0422/buwenbuhuo/test"));

            // 3 关闭资源
            fs.close();
        }
    }