c 网站开发入门视频,react网站开发,wordpress dante 下载,青岛设计公司排名实现bean对象序列化步骤 自定义bean对象实现序列化接口。
1#xff09;必须实现Writable接口
2#xff09;反序列化时#xff0c;需要反射调用空参构造函数#xff0c;所以必须有空参构造
public FlowBean(){super();
}
3#xff09;重写序列化方法
Override
public …实现bean对象序列化步骤 自定义bean对象实现序列化接口。
1必须实现Writable接口
2反序列化时需要反射调用空参构造函数所以必须有空参构造
public FlowBean(){super();
}
3重写序列化方法
Override
public void write(DataOutput out) throws IOException{out.writeLong(upFlow);out.writeLong(downFlow);out.wirteLong(sumFlow);
}
4重写反序列化方法
override
public void readFields(DataInput in) throws IOException{upFlow in.readLong();downFlow in.readLong();sumFlow in.readLong();
}
5注意反序列化顺序和序列化顺序要完全一致
6要想把结果显示在文件中需要重写toString()方法可用\t分开方便后续使用
7如果需要将自定义的bean放在key中传输则还需要实现Comparable接口因为MapReduce框中的shuffle过程要求对key必须能排序
Override
public int compareTo(FlowBean o){return this.sumFlow o.getSumFlow() ? -1 : 1;
}
代码案例统计流量
FlowBean
public class FlowBean implements Writable {private long upFlow;private long downFlow;private long sumFlow;public FlowBean() {}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 getSumFlow() {return sumFlow;}public void setSumFlow(long sumFlow) {this.sumFlow sumFlow;}public void setSumFlow() {this.sumFlow this.upFlow this.downFlow;}Overridepublic void write(DataOutput dataOutput) throws IOException {dataOutput.writeLong(upFlow);dataOutput.writeLong(downFlow);dataOutput.writeLong(sumFlow);}Overridepublic void readFields(DataInput dataInput) throws IOException {this.upFlow dataInput.readLong();this.downFlow dataInput.readLong();this.sumFlow dataInput.readLong();}Overridepublic String toString() {return upFlow \t downFlow \t sumFlow ;}
}FlowMapper
public class FlowMapper extends MapperLongWritable, Text,Text,FlowBean {private Text outK new Text();private FlowBean outV new FlowBean();Overrideprotected void map(LongWritable key, Text value, MapperLongWritable, Text, Text, FlowBean.Context context) throws IOException, InterruptedException {String line value.toString();String[] split line.split( );String phone split[1];String upFlow split[2];String downFlow split[3];outK.set(phone);outV.setUpFlow(Long.parseLong(upFlow));outV.setDownFlow(Long.parseLong(downFlow));// outV.setSumFlow(Long.parseLong(upFlow) Long.parseLong(downFlow));outV.setSumFlow();context.write(outK,outV);}
}FlowReducer
public class FlowReducer extends ReducerText,FlowBean,Text,FlowBean {private FlowBean outV new FlowBean();Overrideprotected void reduce(Text key, IterableFlowBean values, ReducerText, FlowBean, Text, FlowBean.Context context) throws IOException, InterruptedException {long totalUpFlow 0;long totalDownFlow 0;for (FlowBean value : values) {totalUpFlow value.getUpFlow();totalDownFlow value.getDownFlow();}outV.setUpFlow(totalUpFlow);outV.setDownFlow(totalDownFlow);outV.setSumFlow();context.write(key,outV);}
}FlowDriver
public class FlowDriver{public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {Configuration conf new Configuration();Job job Job.getInstance(conf);job.setJarByClass(FlowDriver.class);job.setMapperClass(FlowMapper.class);job.setReducerClass(FlowReducer.class);job.setMapOutputKeyClass(Text.class);job.setMapOutputValueClass(FlowBean.class);FileInputFormat.setInputPaths(job,new Path(Data/input/TestFlowBean));FileOutputFormat.setOutputPath(job,new Path(Data/output/TestFlow3));Boolean result job.waitForCompletion(true);System.exit(result ? 0:1);}
}
