近期因为一个需求,要把MySQL
中的数据按照指定格式同步到HDFS
中,以作后续分析使用(实际可以使用sqoop
,但这里暂不考虑),实现方法是使用MapReduce
程序来实现,但在使用过程中,遇到了java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
错误,各种测试、搜索无果。
下面贴出代码
- LoginDaysMapReduce
package com.zlikun.learning.mysql.logins;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.db.DBConfiguration;
import org.apache.hadoop.mapreduce.lib.db.DBInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import java.io.IOException;
/**
* 登录日期mapreduce程序,输出$userId + $date到HDFS中,以供后续使用
* @author zlikun <zlikun-dev@hotmail.com>
* @date 2018-01-16 11:39
*/
public class LoginDaysMapReduce extends Configured implements Tool {
/**
* 将数据库中数据映射为:$userId + $date(与1970的相关天数) 格式
*/
public static class LoginDaysMapper extends Mapper<LongWritable, TblRecord, Text, NullWritable> {
@Override
protected void map(LongWritable key, TblRecord value, Context context) throws IOException, InterruptedException {
if (value.days > 0) {
context.write(new Text(value.toString()), NullWritable.get());
}
}
}
@Override
public int run(String[] args) throws Exception {
Job job = Job.getInstance(this.getConf(), this.getClass().getSimpleName());
job.setJarByClass(LoginDaysMapReduce.class);
// 配置MapReduce程序
job.setMapperClass(LoginDaysMapper.class);
job.setNumReduceTasks(0);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(NullWritable.class);
job.setInputFormatClass(DBInputFormat.class);
FileOutputFormat.setOutputPath(job, new Path("hdfs://zlikun:9000/login_days/example"));
job.addArchiveToClassPath(new Path("/lib/mysql/mysql-connector-java-5.1.45.jar"));
DBConfiguration.configureDB(job.getConfiguration(),
"com.mysql.jdbc.Driver",
"jdbc:mysql://192.168.xxx.xxx:3306/logins",
"root",
"******");
String [] fields = {"USER_ID", "LOGIN_TIME"};
DBInputFormat.setInput(job, TblRecord.class,
"TBL_LOGIN_LOG", null, null, fields);
return job.waitForCompletion(true) ? 1 : 0 ;
}
/**
* args[0] jdbcUrl
* args[1] username
* args[2] password
* args[3] tableName
* args[4] outputPath
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
int status = ToolRunner.run(conf, new LoginDaysMapReduce(), args);
System.exit(status);
}
}
- TblRecord
package com.zlikun.learning.mysql.logins;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapreduce.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;
import java.sql.Timestamp;
import java.time.Instant;
import java.time.ZoneId;
/**
* MySQL 表记录,用于读写MySQL表数据使用
* @author zlikun <zlikun-dev@hotmail.com>
* @date 2018-01-16 11:53
*/
public class TblRecord implements Writable, DBWritable {
Long userId ; // 用户ID
Long days; // 登录日期距1970/1/1天数(方便后续按序列处理数据,以统计连续登录天数)
@Override
public void write(DataOutput dataOutput) throws IOException {
dataOutput.writeLong(this.userId);
dataOutput.writeLong(this.days);
}
@Override
public void readFields(DataInput dataInput) throws IOException {
this.userId = dataInput.readLong();
this.days = dataInput.readLong();
}
@Override
public void write(PreparedStatement statement) throws SQLException {
statement.setLong(1, this.userId);
statement.setLong(2, this.days);
}
@Override
public void readFields(ResultSet resultSet) throws SQLException {
this.userId = resultSet.getLong(1);
Timestamp loginTime = resultSet.getTimestamp(2);
if (loginTime != null) {
this.days = Instant.ofEpochMilli(loginTime.getTime()).atZone(ZoneId.systemDefault()).toLocalDate().toEpochDay();
} else {
this.days = -1L;
}
}
@Override
public String toString() {
return this.userId + ":" + this.days;
}
}
打包后(mr.jar
),在Hadoop
(版本:2.7.4
)上执行,报出如下错误:
$ hadoop jar mr.jar com.zlikun.learning.mysql.logins.LoginDaysMapReduce
18/01/16 17:17:14 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:8032
18/01/16 17:17:15 INFO mapreduce.JobSubmitter: Cleaning up the staging area /tmp/hadoop-yarn/staging/zlikun/.staging/job_1516093190077_0003
Exception in thread "main" java.lang.RuntimeException: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.setConf(DBInputFormat.java:171)
at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:76)
at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:136)
at org.apache.hadoop.mapreduce.JobSubmitter.writeNewSplits(JobSubmitter.java:299)
at org.apache.hadoop.mapreduce.JobSubmitter.writeSplits(JobSubmitter.java:318)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:196)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1290)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1287)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1746)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1287)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1308)
at com.zlikun.learning.mysql.logins.LoginDaysMapReduce.run(LoginDaysMapReduce.java:62)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at com.zlikun.learning.mysql.logins.LoginDaysMapReduce.main(LoginDaysMapReduce.java:76)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.hadoop.util.RunJar.run(RunJar.java:221)
at org.apache.hadoop.util.RunJar.main(RunJar.java:136)
Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.createConnection(DBInputFormat.java:205)
at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.setConf(DBInputFormat.java:164)
... 21 more
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at org.apache.hadoop.mapreduce.lib.db.DBConfiguration.getConnection(DBConfiguration.java:148)
at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.createConnection(DBInputFormat.java:198)
... 22 more
实际上驱动JAR包已经上传至HDFS
上了
$ hdfs dfs -ls /lib/mysql/mysql-connector-java-5.1.45.jar
-rw-r--r-- 1 zlikun supergroup 999808 2018-01-16 16:35 /lib/mysql/mysql-connector-java-5.1.45.jar
目前采用将
mysql
驱动包打入程序包中的方式解决,暂时未找到其它的实现方法,后面发现的话我再补充。