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-