MapReduce当中排序sort的方法

最新推荐文章于 2024-06-14 01:24:13 发布

转载最新推荐文章于 2024-06-14 01:24:13 发布 · 460 阅读

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原文链接：https://blog.youkuaiyun.com/mark_to_win/article/details/90376369

文章标签：

#排序sort #Hadoop #MapReduce

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本文介绍如何使用Hadoop MapReduce技术框架实现排序功能，通过自定义类OrderBeanSort实现WritableComparable接口，以支持按id和amount字段进行排序。文章提供了完整的代码示例。

排序sort：

防盗版实名手机尾号：73203。注意：想自己实现Sort得不偿失，但如想借助Hadoop MapReduce技术框架排序，key必须实现WritableComparable接口。具体做法见下。需求是先按id比，再按amount比。
package com;
import org.apache.hadoop.io.WritableComparable;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
public class OrderBeanSort implements WritableComparable<OrderBeanSort>{
    private String orderId;
    private Double amount;
    private Double average=0.0;
    public Double getAverage() {
        return average;
    }
    public void setAverage(Double average) {
        this.average = average;
    }
    public OrderBeanSort() {
    }

    public OrderBeanSort(String orderId, Double amount) {
        this.orderId = orderId;
        this.amount = amount;
    }
    public void set(String orderId, Double amount) {
        this.orderId = orderId;
        this.amount = amount;
    }
    public String getOrderId() {
        return orderId;
    }

    public void setOrderId(String orderId) {
        this.orderId = orderId;
    }

    public Double getAmount() {
        return amount;
    }

    public void setAmount(Double amount) {
        this.amount = amount;
    }

    public void write(DataOutput out) throws IOException {
        out.writeUTF(orderId);
        out.writeDouble(amount);
        out.writeDouble(average);
    }

  更多请见：http://www.mark-to-win.com/tutorial/mydb_MapReduce_Sort.html