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://*.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。