MapReduce当中排序sort的方法

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);

}

更多请见：https://blog.csdn.net/qq_44594249/article/details/97236398