1.排序概述
2.排序分类
3.WritableComparable案例
大数据-Hadoop生态(18)-MapReduce框架原理-WritableComparable排序和GroupingComparator分组
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字段含义分别为手机号,上行流量,下行流量,总流量
需求是根据总流量进行排序
Bean对象,需要实现序列化,反序列化和Comparable接口
package com.nty.writableComparable; import org.apache.hadoop.io.WritableComparable; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; /** * author nty * date time 2018-12-12 16:33 *//** * 实现WritableComparable接口 * 原先将bean序列化时,需要实现Writable接口,现在再实现Comparable接口 * * public interface WritableComparable<T> extends Writable, Comparable<T> * * 所以我们可以实现Writable和Comparable两个接口,也可以实现WritableComparable接口 */public class Flow implements WritableComparable<Flow> { private long upflow; private long downflow; private long total; public long getUpflow() { return upflow; } public void setUpflow(long upflow) { this.upflow = upflow; } public long getDownflow() { return downflow; } public void setDownflow(long downflow) { this.downflow = downflow; } public long getTotal() { return total; } public void setTotal(long total) { this.total = total; } //快速赋值 public void setFlow(long upflow, long downflow){ this.upflow = upflow; this.downflow = downflow; this.total = upflow + downflow; } @Override public String toString() { return upflow + "\t" + downflow + "\t" + total; } //重写compareTo方法 @Override public int compareTo(Flow o) { return Long.compare(o.total, this.total); } //
