Hadoop mysql读写操作

使用DBWritable完成同mysql交互

create database big4 ;
		use big4 ;
		create table words(id int primary key auto_increment , name varchar(20) , txt varchar(255));
		
		insert into words(name,txt) values('tomas','hello world tom');
		insert into words(name,txt) values('tomas1','hello tom world'); 
		insert into  words(name,txt) values('tomas2','world hello tom');
		insert into  words(name,txt) values('tomas3','world tom hello');


create table stats(word varchar(50),c int);

编写hadoop MyDBWritable.

package com.mao.hdfs.mysql;

import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapred.lib.db.DBWritable;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MyDBWritable implements DBWritable, Writable {

    private int id;
    private String name;
    private  String txt;
    private String word;
    private int c;

    public String getWord() {
        return word;
    }

    public void setWord(String word) {
        this.word = word;
    }

    public int getC() {
        return c;
    }

    public void setC(int c) {
        this.c = c;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getTxt() {
        return txt;
    }

    public void setTxt(String txt) {
        this.txt = txt;
    }

    /**
     * 写入DB
     * @param ppst
     * @throws SQLException
     */
    public void write(PreparedStatement ppst) throws SQLException {
        //ppst.setInt(1,id);
//        ppst.setString(2,name);
//        ppst.setString(3,txt);
        ppst.setString(1,word);
        ppst.setInt(2,c);
    }


    /**
     * 读取db
     * @param rs
     * @throws SQLException
     */
    public void readFields(ResultSet rs) throws SQLException {
        id = rs.getInt(1);
        name = rs.getString(2);
        txt = rs.getString(3);
    }

    /**
     * 写入数据
     * @param out
     * @throws IOException
     */
    public void write(DataOutput out) throws IOException {
        out.writeInt(id);
        out.writeUTF(name);
        out.writeUTF(txt);
        out.writeUTF(word);
        out.write(c);
    }

    /**
     * 读取数据
     * @param in
     * @throws IOException
     */
    public void readFields(DataInput in) throws IOException {
        id = in.readInt();
        name = in.readUTF();
        txt = in.readUTF();
        word = in.readUTF();
        c = in.readInt();
    }
}

mapper类：

package com.mao.hdfs.mysql;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class WCMapper extends Mapper<LongWritable,MyDBWritable,Text,IntWritable> {

    protected void map(LongWritable key, MyDBWritable value, Context context) throws IOException, InterruptedException, IOException {
        System.out.println(key);
        String line = value.getTxt();
        System.out.println(value.getId() + "," + value.getName());
        String[] arr = line.split(" ");
        for (String s : arr) {
            context.write(new Text(s), new IntWritable(1));
        }
    }
}

reduce类：

package com.mao.hdfs.mysql;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class WCMapper extends Mapper<LongWritable,MyDBWritable,Text,IntWritable> {

    protected void map(LongWritable key, MyDBWritable value, Context context) throws IOException, InterruptedException, IOException {
        System.out.println(key);
        String line = value.getTxt();
        System.out.println(value.getId() + "," + value.getName());
        String[] arr = line.split(" ");
        for (String s : arr) {
            context.write(new Text(s), new IntWritable(1));
        }
    }
}

APP类：

package com.mao.hdfs.mysql;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.lib.db.DBConfiguration;
import org.apache.hadoop.mapred.lib.db.DBInputFormat;
import org.apache.hadoop.mapred.lib.db.DBOutputFormat;
import org.apache.hadoop.mapreduce.Job;

public class MysqlApp {
    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        //conf.set("fs.defaultFS","file:///");  

        Job job = Job.getInstance(conf);
        //设置job属性
        job.setJobName("MysqlApp");                                    //作业名称
        job.setJarByClass(MysqlApp.class);                             //搜索类

        //配置数据库信息
        String driverClass = "com.mysql.jdbc.Driver";
        String url = "jdbc:mysql://192.168.0.21:3306/big1";
        String username = "bgm";
        String password = "12311";

        //设置数据库配置
        DBConfiguration.configureDB(job.getConfiguration(),driverClass,url,username,password);
        //设置数据输入内容
        DBInputFormat.setInput(job,MyDBWritable.class,"select * from words","select count(*) from words");

        DBOutputFormat.setOutput(job,"stats","word","c"); //将结果写入数据库

        //FileOutputFormat.setOutputPath(job,new Path("d:/mr/sql/out"));       //输出路径

        job.setMapperClass(WCMapper.class);                         //mapper类
        job.setReducerClass(WCReducer.class);                       //reduce类

        job.setNumReduceTasks(3);                                   //reduce个数

        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);

        job.waitForCompletion(true);
    }
}

最后

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