通过mapreduce把mysql的一张表的数据导到另外一张表中

怎么安装hadoop集群我在这里就不多说了，我这里安装的是三节点的集群

先在主节点安装mysql

启动mysql

登录mysql

创建数据库，创建表格，先把数据加载到表格 t ,表格t2是空的

mysql> create database mrtest;
Query OK, 1 row affected (0.05 sec)

mysql> use mrtest;
Database changed
mysql> CREATE TABLE `t` (
    -> `id` int DEFAULT NULL,
    -> `name` varchar(10) DEFAULT NULL
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.07 sec)

mysql> CREATE TABLE `t2` (
    -> `id` int DEFAULT NULL,
    -> `name` varchar(10) DEFAULT NULL
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.01 sec)

mysql> insert into t values (1,"june"),(2,"decli"),(3,"hello"),
    ->         (4,"june"),(5,"decli"),(6,"hello"),(7,"june"),
    ->         (8,"decli"),(9,"hello"),(10,"june"),
    ->         (11,"june"),(12,"decli"),(13,"hello");
Query OK, 13 rows affected (0.01 sec)
Records: 13  Duplicates: 0  Warnings: 0

配置一下mysql数据库

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | localhost  | *6865AFFB6CE8FA9ED6A74985497DDD53FF3B8BAA |
| root | cdh-master |                                           |
| root | 127.0.0.1  |                                           |
|      | localhost  |                                           |
|      | cdh-master |                                           |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | cdh-master | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | localhost  | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
8 rows in set (0.04 sec)

mysql> delete from user where user=' ';
ERROR 1146 (42S02): Table 'mrtest.user' doesn't exist
mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> delete from user where user=' ';
Query OK, 2 rows affected (0.05 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | localhost  | *6865AFFB6CE8FA9ED6A74985497DDD53FF3B8BAA |
| root | cdh-master |                                           |
| root | 127.0.0.1  |                                           |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | cdh-master | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | localhost  | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
6 rows in set (0.00 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | localhost  | *6865AFFB6CE8FA9ED6A74985497DDD53FF3B8BAA |
| root | cdh-master |                                           |
| root | 127.0.0.1  |                                           |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | cdh-master | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | localhost  | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
6 rows in set (0.00 sec)

mysql> delete from user where host='127.0.0.1';
Query OK, 1 row affected (0.03 sec)

mysql> delete from user where host='localhost';
Query OK, 2 rows affected (0.00 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | cdh-master |                                           |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | cdh-master | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
3 rows in set (0.01 sec)

mysql> delete from user where user='hive';
Query OK, 2 rows affected (0.00 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+----------+
| user | host       | password |
+------+------------+----------+
| root | cdh-master |          |
+------+------------+----------+
1 row in set (0.00 sec)

mysql> grant all privileges on hive.* to hive@'%' identified by 'hive' with grant option;
Query OK, 0 rows affected (0.06 sec)

mysql> grant all privileges on hive.* to hive@'master' identified by 'hive' with grant option;
Query OK, 0 rows affected (0.00 sec)

mysql> grant all privileges on hive.* to hive@'localhost' identified by 'hive' with grant option;
Query OK, 0 rows affected (0.00 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | cdh-master |                                           |
| hive | localhost  | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | master     | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
4 rows in set (0.00 sec)

mysql> grant all privileges on *.* to root@'%' identified by 'root';
Query OK, 0 rows affected (0.02 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | %          | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B |
| root | cdh-master |                                           |
| hive | localhost  | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | master     | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
5 rows in set (0.00 sec)

mysql> grant all privileges on *.* to root@'%' identified by '543116';
Query OK, 0 rows affected (0.00 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | %          | *6865AFFB6CE8FA9ED6A74985497DDD53FF3B8BAA |
| root | cdh-master |                                           |
| hive | localhost  | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | master     | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
5 rows in set (0.00 sec)

mysql> GRANT ALL PRIVILEGES on *.* to 'root'@'localhost' identified by '543116';
Query OK, 0 rows affected (0.00 sec)

mysql>  select user,host,password from mysql.user;
+------+------------+-------------------------------------------+
| user | host       | password                                  |
+------+------------+-------------------------------------------+
| root | %          | *6865AFFB6CE8FA9ED6A74985497DDD53FF3B8BAA |
| root | cdh-master |                                           |
| root | localhost  | *6865AFFB6CE8FA9ED6A74985497DDD53FF3B8BAA |
| hive | localhost  | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | %          | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | master     | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+------------+-------------------------------------------+
6 rows in set (0.00 sec)

mysql> use mrtest;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
+------------------+
| Tables_in_mrtest |
+------------------+
| t                |
| t2               |
+------------------+
2 rows in set (0.00 sec)

在eclipse创建mapreduce项目

在这里说一下我这里是安装的是hadoop2.6.0版本的

如果没有添加对应的hadoop插件的话就这样添加

现在你本地安装的eclipse的dropins文件夹了放入这个插件，然后重新启动eclipse

重启之后

我们可以看到多了这么一项

在这里选定本地安装的hadoop

接下来是加载mysql的驱动包

这个是我本地的mysql驱动包

在eclipse加载驱动包之后还需要在集群里加载

把驱动包上传的每个节点的hadoop安装目录的lib目录下，是所有节点

把集群启动一下，我这里只是搭建了分布式的3节点没有搭建HA

我们现在hdfs上创建一个目录来存放mysql的驱动包

把本地的驱动包上传的hdfs上

在代码里面要加上这句来实现

DistributedCache.addFileToClassPath(new Path("hdfs://192.168.241.13:9000/mysqlconnector/mysql-connector-java-5.1.38-bin.jar"), conf);

下面是运行代码

package com.gong.mrmysql;

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

import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.lib.IdentityReducer;
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.mapred.lib.db.DBWritable;

/**
* Function: 测试 mr 与 mysql 的数据交互，此测试用例将一个表中的数据复制到另一张表中
*                          实际当中，可能只需要从 mysql 读，或者写到 mysql 中。
* date: 2013-7-29 上午2:34:04 <br/>
* @author june
*/
public class Mysql2Mr {
        // DROP TABLE IF EXISTS `hadoop`.`studentinfo`;
        // CREATE TABLE studentinfo (
        // id INTEGER NOT NULL PRIMARY KEY,
        // name VARCHAR(32) NOT NULL);

        public static class StudentinfoRecord implements Writable, DBWritable {
                int id;
                String name;

                public StudentinfoRecord() {

                }

                public void readFields(DataInput in) throws IOException {
                        this.id = in.readInt();
                        this.name = Text.readString(in);
                }

                public String toString() {
                        return new String(this.id + " " + this.name);
                }

                @Override
                public void write(PreparedStatement stmt) throws SQLException {
                        stmt.setInt(1, this.id);
                        stmt.setString(2, this.name);
                }

                @Override
                public void readFields(ResultSet result) throws SQLException {
                        this.id = result.getInt(1);
                        this.name = result.getString(2);
                }

                @Override
                public void write(DataOutput out) throws IOException {
                        out.writeInt(this.id);
                        Text.writeString(out, this.name);
                }
        }

        // 记住此处是静态内部类，要不然你自己实现无参构造器，或者等着抛异常：
        // Caused by: java.lang.NoSuchMethodException: DBInputMapper.<init>()
        // http://stackoverflow.com/questions/7154125/custom-mapreduce-input-format-cant-find-constructor
        // 网上脑残式的转帖，没见到一个写对的。。。
        public static class DBInputMapper extends MapReduceBase implements
                        Mapper<LongWritable, StudentinfoRecord, LongWritable, Text> {
                public void map(LongWritable key, StudentinfoRecord value,
                                OutputCollector<LongWritable, Text> collector, Reporter reporter) throws IOException {
                        collector.collect(new LongWritable(value.id), new Text(value.toString()));
                }
        }

        public static class MyReducer extends MapReduceBase implements
                        Reducer<LongWritable, Text, StudentinfoRecord, Text> {
                @Override
                public void reduce(LongWritable key, Iterator<Text> values,
                                OutputCollector<StudentinfoRecord, Text> output, Reporter reporter) throws IOException {
                        String[] splits = values.next().toString().split(" ");
                        StudentinfoRecord r = new StudentinfoRecord();
                        r.id = Integer.parseInt(splits[0]);
                        r.name = splits[1];
                        output.collect(r, new Text(r.name));
                }
        }

        public static void main(String[] args) throws IOException {
                JobConf conf = new JobConf(Mysql2Mr.class);
                DistributedCache.addFileToClassPath(new Path("hdfs://192.168.241.13:9000/mysqlconnector/mysql-connector-java-5.1.38-bin.jar"), conf);

                conf.setMapOutputKeyClass(LongWritable.class);
                conf.setMapOutputValueClass(Text.class);
                conf.setOutputKeyClass(LongWritable.class);
                conf.setOutputValueClass(Text.class);

                conf.setOutputFormat(DBOutputFormat.class);
                conf.setInputFormat(DBInputFormat.class);
                // // mysql to hdfs
                // conf.setReducerClass(IdentityReducer.class);
                // Path outPath = new Path("/tmp/1");
                // FileSystem.get(conf).delete(outPath, true);
                // FileOutputFormat.setOutputPath(conf, outPath);

                DBConfiguration.configureDB(conf, "com.mysql.jdbc.Driver", "jdbc:mysql://192.168.241.13:3306/mrtest",
                                "root", "543116");
                String[] fields = { "id", "name" };
                // 从 t 表读数据
                DBInputFormat.setInput(conf, StudentinfoRecord.class, "t", null, "id", fields);
                // mapreduce 将数据输出到 t2 表
                DBOutputFormat.setOutput(conf, "t2", "id", "name");
                // conf.setMapperClass(org.apache.hadoop.mapred.lib.IdentityMapper.class);
                conf.setMapperClass(DBInputMapper.class);
                conf.setReducerClass(MyReducer.class);

                JobClient.runJob(conf);
        }
}

我们运行一下

通过mysql查看t2表看看有没有数据

再运行一次，可以看到t2表又一次被加载进数据了

这里我们就实现了怎么用mapreduce把mysql的一张表的数据加载到另外一张表去了。