地图reduce写数据至mysql

package com.sun.mysql;   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.conf.Configuration; 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.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; import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;   /**  * 将mapreduce的结果数据写入mysql中  * @author asheng  */ public class WriteDataToMysql { /**      * 重写DBWritable      * @author asheng      * TblsWritable需要向mysql中写入数据      */     public static class TblsWritable implements Writable, DBWritable      {               String tbl_name;               String tbl_type;               public TblsWritable()              {                            }               public TblsWritable(String tbl_name,String tab_type)              {               this.tbl_name = tbl_name;             this.tbl_type = tab_type;             }               @Override               public void write(PreparedStatement statement) throws SQLException              {                     statement.setString(1, this.tbl_name);                       statement.setString(2, this.tbl_type);               }               @Override               public void readFields(ResultSet resultSet) throws SQLException              {                       this.tbl_name = resultSet.getString(1);                       this.tbl_type = resultSet.getString(2);               }               @Override               public void write(DataOutput out) throws IOException              {                       out.writeUTF(this.tbl_name);                     out.writeUTF(this.tbl_type);             }               @Override               public void readFields(DataInput in) throws IOException              {                       this.tbl_name = in.readUTF();                       this.tbl_type = in.readUTF();               }               public String toString()              {                   return new String(this.tbl_name + " " + this.tbl_type);               }       }      public static class ConnMysqlMapper extends Mapper<LongWritable,Text,Text,Text>     //TblsRecord是自定义的类型，也就是上面重写的DBWritable类    {           public void map(LongWritable key,Text value,Context context)throws IOException,InterruptedException          {           //<首字母偏移量,该行内容>接收进来，然后处理value，将abc和x作为map的输出         //key对于本程序没有太大的意义，没有使用         String name = value.toString().split(" ")[0];         String type = value.toString().split(" ")[1];                 context.write(new Text(name),new Text(type));           }      }       public static class ConnMysqlReducer extends Reducer<Text,Text,TblsWritable,TblsWritable>      {           public void reduce(Text key,Iterable<Text> values,Context context)throws IOException,                                                                                                                 InterruptedException          {           //接收到的key value对即为要输入数据库的字段，所以在reduce中：         //wirte的第一个参数，类型是自定义类型TblsWritable，利用key和value将其组合成TblsWritable，                                                                                                                     然后等待写入数据库         //wirte的第二个参数，wirte的第一个参数已经涵盖了要输出的类型，所以第二个类型没有用，设为null         for(Iterator<Text> itr = values.iterator();itr.hasNext();)                   {                        context.write(new TblsWritable(key.toString(),itr.next().toString()),null);                   }           }       }       public static void main(String args[]) throws IOException, InterruptedException, ClassNotFoundException     {         Configuration conf = new Configuration();           DBConfiguration.configureDB(conf, "com.mysql.jdbc.Driver","jdbc:mysql://127.0.0.1:3306/mapreduce_test",                                                                                                                                               "root", "root");             Job job = new Job(conf,"test mysql connection");           job.setJarByClass(ReadDataFromMysql.class);                      job.setMapperClass(ConnMysqlMapper.class);           job.setReducerClass(ConnMysqlReducer.class);                      job.setOutputKeyClass(Text.class);           job.setOutputValueClass(Text.class);                   job.setInputFormatClass(TextInputFormat.class);           job.setOutputFormatClass(DBOutputFormat.class);         FileInputFormat.addInputPath(job, new Path(args[0]));                  DBOutputFormat.setOutput(job, "lxw_tabls", "TBL_NAME","TBL_TYPE");         System.exit(job.waitForCompletion(true) ? 0 : 1);     } } //执行输入参数为/home/asheng/hadoop/in/test3.txt //test3.txt中的内容为 /* abc x def y chd z */ //即将abc x分别做为TBL_NAME,和TBL_TYPE插入数据库中   //输出结果在mysql数据库中查看 //select * from lxw_tabls; //发现新增三行 /* abc x def y chd z */  

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