MapReduce当中排序sort的方法

最新推荐文章于 2025-09-18 19:34:54 发布

原创最新推荐文章于 2025-09-18 19:34:54 发布 · 712 阅读

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#排序sort #Hadoop #MapReduce #马克-to-win #马克java社区

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本文介绍如何在Hadoop MapReduce框架中实现自定义排序，通过实现WritableComparable接口完成复杂数据结构的排序需求，示例代码展示了根据订单ID和金额进行排序的具体实现。

排序sort：
马克-to-win @ 马克java社区：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);
    }