将文件以API方式导入到HBase(小文件处理)

前面我们搭建了Hadoop及HBase本地开发环境,(参见前文:Win7 64位系统上Hadoop单机模式的安装及开发环境搭建,Win7 64位系统上HBase单机模式的安装)多数情况下,对于MapReduce模型,其底层使用HDFS作为存储,在HDFS中,其NameNode节点保存的是文件的元数据,DataNode保存真正的文件数据,如果是大型数据文件,这没有任何问题,但如果对于大量的小文件,其不足也是很明显的,NameNode中因为大量的小文件的元数据,占用大量的内存空间,将使得HDFS性能受到很大影响,一个可行的方案是,将大量小文件保存到HBase中,本文及后续文章讨论的是以HBase作为存储,如何将小文件或大文件导入到HBase中去,每个小文件将保存在独立的cell中,而对于大文件,将先上传到HDFS中,然后再使用MapReduce方法,将文件内容读入到HBase中。

 

场景描述

对于小文件,我这里假设不足10M,这样我们就不需要对文件split并保存到不同的cell中,在HBase中,每一个行与列的交汇处,称为一个cell,其默认上限是10M,当然这个是可以通过配置文件调整的,调整的配置项是 “hbase.client.keyvalue.maxsize”,其默认值是10485760。对于文件源,可以是本地的文件,本测试用例中使用的是本地的email文件,大小才15k左右,我们将创建一个本地Java工程,读取本地文件后,再通过API保存到HBase中。另外一个可能的场景是,将本地程序变换为一个RESTful API,外部系统远程调用这个RESTful API,将数据存到HBase中,通过这个API,可以串起2个独立的系统。

 

项目步骤:

1:在IDEA中创建一个Java Maven工程

将文件以API方式导入到HBase(小文件处理)_第1张图片

2: 修改pom.xml,引入hbase 1.2.6,因为要使用API操作HBase

xml version="1.0" encoding="UTF-8"?>
<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>4.0.0modelVersion>

    <groupId>ImportFilegroupId>
    <artifactId>ImportFileartifactId>
    <version>1.0-SNAPSHOTversion>

    <repositories>
        <repository>
            <id>apacheid>
            <url>http://maven.apache.orgurl>
        repository>
    repositories>

    <dependencies>
        <dependency>
            <groupId>org.apache.hbasegroupId>
            <artifactId>hbase-clientartifactId>
            <version>1.2.6version>
        dependency>
    dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-shade-pluginartifactId>
                <executions>
                    
                    <execution>
                        <phase>packagephase>
                        <goals>
                            <goal>shadegoal>
                        goals>
                        <configuration>
                            <filters>
                                <filter>
                                    
                                    <artifact>*:*artifact>
                                    <excludes>
                                        <exclude>META-INF/*.SFexclude>
                                        <exclude>META-INF/*.DSAexclude>
                                        <exclude>META-INF/*.RSAexclude>
                                    excludes>
                                filter>
                            filters>

                            <createDependencyReducedPom>falsecreateDependencyReducedPom>
                        configuration>
                    execution>
                executions>
            plugin>

            <plugin>
                <groupId>org.apache.maven.pluginsgroupId>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>1.8source>
                    <target>1.8target>
                configuration>
            plugin>

        plugins>
    build>
project>

3:添加处理HBase的类HbaseUtility,分别包含表的创建,添加,删除,查询数据的方法

package examples;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;

import java.io.IOException;


public class HBaseUtility {
    static String TABLE_NAME = "email";
    static String[] COLUMN_FAMILY = {"cf1"};
    static String[] COLUMNS = {"message"};

    public static void HBaseOperation(String fileContent) {
        //*******************************************************//
        Connection conn = null;
        Admin admin = null;
        try {
            Configuration conf = HBaseConfiguration.create();
            conn = ConnectionFactory.createConnection(conf);
            admin = conn.getAdmin();

            TableName tableName = TableName.valueOf(TABLE_NAME);
            CreateTable(admin,tableName);
            DeleteData(conn,tableName);
            PutData(conn, tableName, fileContent);
            GetData(conn, tableName);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally
        {
            try {
                if (admin != null) {
                    admin.close();
                }

                if (conn != null) {
                    conn.close();
                }
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }
    }
}

在上面类中添加HBase的操作函数:

    //创建hbase表
    private static void CreateTable(Admin admin, TableName tableName)
    {
        try {
            if (admin.tableExists(tableName)) {
                System.out.println(tableName + " table already exists!");
            } else {
                HTableDescriptor tableDesc = new HTableDescriptor(tableName);
                for (String column : COLUMN_FAMILY) {
                    tableDesc.addFamily(new HColumnDescriptor(column));
                }
                admin.createTable(tableDesc);
                System.out.println(tableName + " is created successfully!");
            }
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

    }

    //保存数据
    private static void PutData(Connection conn, TableName tableName, String rowKey, String fileContent) {
        System.out.println("PUT value..............................................");
        try
        {
            Table table = conn.getTable(tableName);
            Put put = new Put (rowKey.getBytes());
            put.addColumn(COLUMN_FAMILY[0].getBytes(), COLUMNS[0].getBytes(), fileContent.getBytes());
            table.put(put);
            table.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    //查询数据
    private static void GetData(Connection conn, TableName tableName, String rowKey) {
        System.out.println("GET value..............................................");
        try
        {
            Table table = conn.getTable(tableName);
            Get get = new Get(rowKey.getBytes());
            //get.addFamily(COLUMN_FAMILY_NAME.getBytes());
            //get.addColumn(COLUMN_FAMILY_NAME.getBytes(),COLUMNS[0].getBytes());
            Result result = table.get(get);
            // get column family
            result.getFamilyMap(COLUMN_FAMILY[0].getBytes()).forEach((k,v) -> System.out.println(new String(k) + ":" + new String(v)));
            table.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    //删除数据
    private static void DeleteData(Connection conn, TableName tableName)
    {
        System.out.println("DELETE value..............................................");
        String rowKey = "row1";
        try
        {
            Table table = conn.getTable(tableName);
            Delete delete = new Delete(rowKey.getBytes());
            delete.addColumn(COLUMN_FAMILY[0].getBytes(),COLUMNS[0].getBytes());
            table.delete(delete);
            table.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

 

4:添加主程序入口,读取本地文件,并调用HBaseUtility方法

package examples;

import java.io.File;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;

public class ImportFile {
    public static void main (String[] args)
    {
        File file = new File("D:\\MyEmail\\Test email successful.eml");
        String fileContent = ReadFile(file);
        HBaseUtility.HBaseOperation(fileContent);
    }

    private static String ReadFile(File file) {
        FileReader fr = null;
        String fileContent = null;
        try {
            StringBuffer sb = new StringBuffer();
            fr = new FileReader(file);
            // 定义字符数组
            char[] buf = new char[1024];// 缓冲区大小
            int len = 0;// 长度读取的字符个数
            while ((len = fr.read(buf)) != -1) {
                System.out.println(new String(buf, 0, len));
                sb.append(buf,0,len);
            }
            fileContent = new String(sb);
            System.out.println(fileContent);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fr != null) {
                try {
                    fr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        return fileContent;
    }
}

5:测试

启动Hadoop,Hbase

cd D:\Application\hadoop-2.7.4\sbin
start-all.cmd

cd D:\Application\hbase-1.2.6\bin
start-hbase.cmd

hbase shell

将可以看到以下的命令行窗口

将文件以API方式导入到HBase(小文件处理)_第2张图片

 

现在可以在IDEA中设置断点,点击调试按钮开始调试了:

 将文件以API方式导入到HBase(小文件处理)_第3张图片

 

转载于:https://www.cnblogs.com/benfly/p/8359825.html

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