MapReduce 写入数据到MySql数据库
文章目录
-
-
- 一、软件版本
- 二、环境配置
- 三、项目结构
- 四、关键代码
- 五、执行jar包
- 六、MySql查询结果
-
Hadoop 0.19中提供的DBInputFormat和DBOutputFormat组件最终允许在Hadoop和许多关系数据库之间轻松导入和导出数据，从而使关系数据更容易地合并到您的数据处理管道中。 要在Hadoop和MySQL之间导入和导出数据，肯定需要在机器上安装Hadoop和MySQL。
一、软件版本
- jdk 1.7.0_79-b15
- hadoop 2.7.1
- mysql 5.0.22
二、环境配置
- 拷贝
mysql-connector-java-5.1.39-bin.jar到$HADOOP_HOME/lib目录。 - 创建MySQL库
mysql> use testDb;
mysql> create table studentinfo ( id integer , name varchar(32) );
mysql> insert into studentinfo values(1,'archana');
mysql> insert into studentinfo values(2,'XYZ');
mysql> insert into studentinfo values(3,'archana');
mysql> create table output ( name varchar(32),count integer );
三、项目结构
要从DB访问数据，我们必须创建一个类来定义要提取并写回DB的数据。在我的项目中，我创建了一个名为DBInputWritable.java和DBOutputWritable.java的类来实现相同的目的。
四、关键代码
DBInputWritable.java
package com.etc;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.lib.db.DBWritable;
public class DBInputWritable implements Writable, DBWritable
{
private int id;
private String name;
public void readFields(DataInput in) throws IOException {
}
public void readFields(ResultSet rs) throws SQLException
//Resultset object represents the data returned from a SQL statement
{
id = rs.getInt(1);
name = rs.getString(2);
}
public void write(DataOutput out) throws IOException {
}
public void write(PreparedStatement ps) throws SQLException
{
ps.setInt(1, id);
ps.setString(2, name);
}
public int getId()
{
return id;
}
public String getName()
{
return name;
}
}
DBOutputWritable.java
package com.etc;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.lib.db.DBWritable;
public class DBOutputWritable implements Writable, DBWritable
{
private String name;
private int count;
public DBOutputWritable(String name, int count)
{
this.name = name;
this.count = count;
}
public void readFields(DataInput in) throws IOException {
}
public void readFields(ResultSet rs) throws SQLException
{
name = rs.getString(1);
count = rs.getInt(2);
}
public void write(DataOutput out) throws IOException {
}
public void write(PreparedStatement ps) throws SQLException
{
ps.setString(1, name);
ps.setInt(2, count);
}
}
Main
package com.etc;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.db.DBConfiguration;
import org.apache.hadoop.mapreduce.lib.db.DBInputFormat;
import org.apache.hadoop.mapreduce.lib.db.DBOutputFormat;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
public class Main
{
public static void main(String[] args) throws Exception
{
Configuration conf = new Configuration();
DBConfiguration.configureDB(conf,
"com.mysql.jdbc.Driver", // driver class
"jdbc:mysql://192.168.191.1:3306/test", // db url
"root", // user name
"root"); //password
Job job = new Job(conf);
job.setJarByClass(Main.class);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(DBOutputWritable.class);
job.setOutputValueClass(NullWritable.class);
job.setInputFormatClass(DBInputFormat.class);
job.setOutputFormatClass(DBOutputFormat.class);
DBInputFormat.setInput(
job,
DBInputWritable.class,
"studentinfo", //input table name
null,
null,
new String[] {
"id", "name" } // table columns
);
DBOutputFormat.setOutput(
job,
"output", // output table name
new String[] {
"name", "count" } //table columns
);
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
Map
package com.etc;
import java.io.IOException;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
public class Map extends Mapper<LongWritable, DBInputWritable, Text, IntWritable>
{
private IntWritable one = new IntWritable(1);
protected void map(LongWritable id, DBInputWritable value, Context ctx)
{
try
{
String[] keys = value.getName().split(" ");
for(String key : keys)
{
ctx.write(new Text(key),one);
}
} catch(IOException e)
{
e.printStackTrace();
} catch(InterruptedException e)
{
e.printStackTrace();
}
}
}
Reduce
package com.etc;
import java.io.IOException;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
public class Reduce extends Reducer<Text, IntWritable, DBOutputWritable, NullWritable>
{
protected void reduce(Text key, Iterable<IntWritable> values, Context ctx)
{
int sum = 0;
for(IntWritable value : values)
{
sum += value.get();
}
try
{
ctx.write(new DBOutputWritable(key.toString(), sum), NullWritable.get());
} catch(IOException e)
{
e.printStackTrace();
} catch(InterruptedException e)
{
e.printStackTrace();
}
}
}
Main
package com.etc;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.db.DBConfiguration;
import org.apache.hadoop.mapreduce.lib.db.DBInputFormat;
import org.apache.hadoop.mapreduce.lib.db.DBOutputFormat;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
public class Main
{
public static void main(String[] args) throws Exception
{
Configuration conf = new Configuration();
DBConfiguration.configureDB(conf,
"com.mysql.jdbc.Driver", // driver class
"jdbc:mysql://192.168.191.1:3306/test", // db url
"root", // user name
"root"); //password
Job job = new Job(conf);
job.setJarByClass(Main.class);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(DBOutputWritable.class);
job.setOutputValueClass(NullWritable.class);
job.setInputFormatClass(DBInputFormat.class);
job.setOutputFormatClass(DBOutputFormat.class);
DBInputFormat.setInput(
job,
DBInputWritable.class,
"studentinfo", //input table name
null,
null,
new String[] {
"id", "name" } // table columns
);
DBOutputFormat.setOutput(
job,
"output", // output table name
new String[] {
"name", "count" } //table columns
);
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
pom.xml
<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>com.etcgroupId>
<artifactId>MapReduce2MySqlartifactId>
<version>1.0-SNAPSHOTversion>
<name>MapReduce2MySqlname>
<url>http://www.example.comurl>
<properties>
<project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
<maven.compiler.source>1.7maven.compiler.source>
<maven.compiler.target>1.7maven.compiler.target>
properties>
<dependencies>
<dependency>
<groupId>org.apache.hadoopgroupId>
<artifactId>hadoop-commonartifactId>
<version>2.7.1version>
<scope>providedscope>
dependency>
<dependency>
<groupId>org.apache.hadoopgroupId>
<artifactId>hadoop-hdfsartifactId>
<version>2.7.1version>
<scope>providedscope>
dependency>
<dependency>
<groupId>org.apache.hadoopgroupId>
<artifactId>hadoop-mapreduce-client-coreartifactId>
<version>2.7.1version>
<scope>providedscope>
dependency>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.11version>
dependency>
dependencies>
<build>
<pluginManagement>
<plugins>
<plugin>
<artifactId>maven-clean-pluginartifactId>
<version>3.1.0version>
plugin>
<plugin>
<artifactId>maven-resources-pluginartifactId>
<version>3.0.2version>
plugin>
<plugin>
<artifactId>maven-compiler-pluginartifactId>
<version>3.8.0version>
plugin>
<plugin>
<artifactId>maven-surefire-pluginartifactId>
<version>2.22.1version>
plugin>
<plugin>
<artifactId>maven-jar-pluginartifactId>
<version>3.0.2version>
plugin>
<plugin>
<artifactId>maven-install-pluginartifactId>
<version>2.5.2version>
plugin>
<plugin>
<artifactId>maven-deploy-pluginartifactId>
<version>2.8.2version>
plugin>
<plugin>
<artifactId>maven-site-pluginartifactId>
<version>3.7.1version>
plugin>
<plugin>
<artifactId>maven-project-info-reports-pluginartifactId>
<version>3.0.0version>
plugin>
plugins>
pluginManagement>
build>
project>
五、执行jar包
$ hadoop jar MapReduce2MySql-1.0-SNAPSHOT.jar com.etc.Main
六、MySql查询结果
mysql> select * from output;
+-----------+-------+
| name | count |
+-----------+-------+
| archana | 2 |
| XYZ | 1 |
+----------+--------+