Hadoop HDFS 客户端测试

拼搏现实的明天。 2022-02-25 03:04 269阅读 0赞

### 文章目录 ###

*   *  依赖
     *  测试demo1
     *   *  代码
         *  配置VM options
         *  查看
     *  测试demo2
     *   *  代码
         *  查看

## 依赖 ##

<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>
    </dependencies>

## 测试demo1 ##

### 代码 ###

package com.yljphp.hdfs;
    
    import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.fs.FileSystem;
    import org.apache.hadoop.fs.Path;
    
    import java.io.IOException;
    
    public class Demo { 
    
        public static void main(String[] args) throws IOException { 
    
            Configuration configuration = new Configuration();
    
            configuration.set("fs.defaultFS", "hdfs://hadoop102:9000");
    
            //获取HDFS客户端对象
            FileSystem fs = FileSystem.get(configuration);
    
            //HDFS上创建文件夹
            fs.mkdirs(new Path("/demo/0331"));
    
            //关闭资源
            fs.close();
    
            System.out.println("ok~~~");
        }
    }

### 配置VM options ###

客户端去操作 hdfs 时，是有一个用户身份的。默认情况下，hdfs 客户端 api 会从 jvm 中 获取一个参数来作为自己的用户身份:-DHADOOP\_USER\_NAME=root

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70]  
如果不添加上面的配置，会报如下错误。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70 1]

### 查看 ###

![\-w1260][-w1260]

## 测试demo2 ##

### 代码 ###

package com.yljphp.hdfs;
    
    import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.fs.FileSystem;
    import org.apache.hadoop.fs.Path;
    
    import java.io.IOException;
    import java.net.URI;
    
    public class Demo { 
    
        public static void main(String[] args) throws Exception { 
    
            Configuration configuration = new Configuration();
    
            configuration.set("fs.defaultFS", "hdfs://hadoop102:9000");
    
            //获取HDFS客户端对象
            //FileSystem fs = FileSystem.get(configuration);
    
            FileSystem fs = FileSystem.get(new URI("hdfs://hadoop102:9000"), configuration, "root");
    
            //HDFS上创建文件夹
            fs.mkdirs(new Path("/demo/0332"));
    
            //关闭资源
            fs.close();
    
            System.out.println("ok~~~");
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70 2]

### 查看 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70 3]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70]: /images/20220225/73333763aa6c4fe1beaa7aa8820b2b81.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70 1]: /images/20220225/6bf7b2733cbc40748684c327de700741.png
[-w1260]: /images/20220225/27421577ecba47daa88a4843241a753c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70 2]: /images/20220225/ae35a22a2bb24606808698d0b4ddf575.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lsanBocA_size_16_color_FFFFFF_t_70 3]: /images/20220225/ae6edb77d49f4b3181fc9bc90a57d7bd.png