利用hadoop命令rcc生成Record 一种简单的方式实现自定义的writable对象

hadoop 的bin目录下面一个rcc命令，网上介绍很少。看了一下源码。发现可以用来生成 java和c++的hadoop Record 类代码，比起自己直接实现writable 接口，简单很多而且不容易出错，不妨试一下。具体方法如下：

>rcc

Usage: rcc --language [java|c++] ddl-files

1 新建 ddl文件

>vim stud.ddl 

module  com.xschao.bean {

   class Stud{

        ustring name;

        long id;

        int age;

        ustring time;



        }

}

 

其他的类型补充，具体是啥自行脑补：

 "\"byte\"",

    "\"boolean\"",

    "\"int\"",

    "\"long\"",

    "\"float\"",

    "\"double\"",

    "\"ustring\"",

    "\"buffer\"",

    "\"vector\"",

    "\"map\"",

2 执行编译命令

> rcc --language java stud.ddl

查看生成的文件：

>tree 

.

|-- com

|   `-- xschao

|       `-- bean

|           `-- Stud.java

|-- command_example.sh

`-- stud.ddl



3 directories, 3 files

Stud.java即为生成的java代码

// File generated by hadoop record compiler. Do not edit.

package com.xschao.bean;



public class Stud extends org.apache.hadoop.record.Record {

  private static final org.apache.hadoop.record.meta.RecordTypeInfo _rio_recTypeInfo;

  private static org.apache.hadoop.record.meta.RecordTypeInfo _rio_rtiFilter;

  private static int[] _rio_rtiFilterFields;

  static {

    _rio_recTypeInfo = new org.apache.hadoop.record.meta.RecordTypeInfo("Stud");

    _rio_recTypeInfo.addField("name", org.apache.hadoop.record.meta.TypeID.StringTypeID);

    _rio_recTypeInfo.addField("id", org.apache.hadoop.record.meta.TypeID.LongTypeID);

    _rio_recTypeInfo.addField("age", org.apache.hadoop.record.meta.TypeID.IntTypeID);

    _rio_recTypeInfo.addField("time", org.apache.hadoop.record.meta.TypeID.StringTypeID);

  }

  

  private String name;

  private long id;

  private int age;

  private String time;

  public Stud() { }

  public Stud(

    final String name,

    final long id,

    final int age,

    final String time) {

    this.name = name;

    this.id = id;

    this.age = age;

    this.time = time;

  }

。。。。。。。。。。。。。。。。。。。。。

ok

格格巫--蓝精灵-