HDFS中的文件写入到Mysql，通过DBConfiguration，DBOutputFormat

        将HDFS中的文件，通过DBConfiguration，DBOutputormat，写入mysql数据库中。

       1.HDFS中文件格式

        name1     1

        name2     2

        name3     3

      2.数据库表test格式

       两个字段

           String name，int   id

      3.DBConfiguration配置

        DBConfiguration.configureDB(conf, "com.mysql.jdbc.Driver", "jdbc:mysql://192.168.1.10:3306/数据库名", "用户名", "密码");

        job.setOutputFormatClass(DBOutputFormat.class);
        DBOutputFormat.setOutput(job, "数据库表名", "字段1","字段2");

      4.写自定义类DataTable，继承DBWritable，Writable，为了完成数据序列化。

      5.经本人测试，用这种方法必须在Reduce阶段的输出key值，将数据写入数据库。否则会报错。本来时想在map阶段的key值就输出的，但是不管用，原因没搞清楚，请各位多多指证。

      附代码：

      

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 org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.LongWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.io.Writable;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.Mapper;import org.apache.hadoop.mapreduce.Reducer;import org.apache.hadoop.mapreduce.lib.db.DBConfiguration;import org.apache.hadoop.mapreduce.lib.db.DBOutputFormat;import org.apache.hadoop.mapreduce.lib.db.DBWritable;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;public class TextToMysql {public static void main(String args[]) throws IOException, ClassNotFoundException, InterruptedException{Configuration conf=new Configuration();DBConfiguration.configureDB(conf, "com.mysql.jdbc.Driver", "jdbc:mysql://192.168.1.10:3306/samples", "root", "1234");Job job=new Job(conf,"mysql");job.setJarByClass(TextToMysql.class);job.setMapperClass(map.class);job.setReducerClass(reduce.class);job.setOutputKeyClass(DataTable.class);job.setOutputValueClass(Text.class);job.setMapOutputKeyClass(Text.class);job.setMapOutputValueClass(Text.class);job.setOutputFormatClass(DBOutputFormat.class);DBOutputFormat.setOutput(job, "test", "name","id");FileInputFormat.addInputPath(job,new Path("hdfs://192.168.1.245:9000/test"));job.waitForCompletion(true);}public static class map extends Mapper<LongWritable,Text,Text,Text>{@Overrideprotected void map(LongWritable key, Text value, Context context)throws IOException, InterruptedException {// TODO Auto-generated method stu  context.write(value, new Text(""));}}public static class reduce extends Reducer<Text,IntWritable,DataTable,Text>{//@Overrideprotected void reduce(Text key, Iterable<IntWritable> value,Context context) throws IOException, InterruptedException {// TODO Auto-generated method stubString args[] = key.toString().split("\t");DataTable da = new DataTable();da.setName(args[0]);da.setId(Integer.parseInt(args[1]));    context.write(da, new Text(""));}}public static class DataTable implements Writable,DBWritable{       private int id;       private String name;       public DataTable(){}        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;}@Overridepublic void write(PreparedStatement statement) throws SQLException {// TODO Auto-generated method stubstatement.setInt(2,this.id);statement.setString(1,this.name);}@Overridepublic void readFields(ResultSet resultSet) throws SQLException {// TODO Auto-generated method stubthis.name=resultSet.getString(1);this.id=resultSet.getInt(2);}@Overridepublic void write(DataOutput out) throws IOException {// TODO Auto-generated method stubout.writeInt(this.id);Text.writeString(out, this.name);}@Overridepublic void readFields(DataInput in) throws IOException {// TODO Auto-generated method stubthis.id=in.readInt();this.name=Text.readString(in);}}}