Flink编程实践

（一）开发WordCount 程序.

在 Linux 系统中实现WordCount 程序，并打包成 JAR 文件，提交到 Flink 中运行。

创建目录用来存放代码：

mkdir -p ~/flinkapp/src/main/java

使用gedit编辑器在“./flinkapp/src/main/java”目录下建立三个代码文件，其中WordCountData.java用于提供原始数据，其内容如下：

package com.xju.wc;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
public class WordCountData {
   
    public static final String[] WORDS=new String[]{
   "To be, or not to be,--that is the question:--", "Whether \'tis nobler in the mind to suffer", "The slings and arrows of outrageous fortune", "Or to take arms against a sea of troubles,", "And by opposing end them?--To die,--to sleep,--", "No more; and by a sleep to say we end", "The heartache, and the thousand natural shocks", "That flesh is heir to,--\'tis a consummation", "Devoutly to be wish\'d. To die,--to sleep;--", "To sleep! perchance to dream:--ay, there\'s the rub;", "For in that sleep of death what dreams may come,", "When we have shuffled off this mortal coil,", "Must give us pause: there\'s the respect", "That makes calamity of so long life;", "For who would bear the whips and scorns of time,", "The oppressor\'s wrong, the proud man\'s contumely,", "The pangs of despis\'d love, the law\'s delay,", "The insolence of office, and the spurns", "That patient merit of the unworthy takes,", "When he himself might his quietus make", "With a bare bodkin? who would these fardels bear,", "To grunt and sweat under a weary life,", "But that the dread of something after death,--", 
"The undiscover\'d country, from whose bourn", "No traveller returns,--puzzles the will,", "And makes us rather bear those ills we have", "Than fly to others that we know not of?", "Thus conscience does make cowards of us all;", "And thus the native hue of resolution", "Is sicklied o\'er with the pale cast of thought;", "And enterprises of great pith and moment,", "With this regard, their currents turn awry,", "And lose the name of action.--Soft you now!", "The fair Ophelia!--Nymph, in thy orisons", "Be all my sins remember\'d."};
    public WordCountData() {
   
    }
    public static DataStream<String> getDefaultTextLineDataStream(StreamExecutionEnvironment senv){
   
        return senv.fromElements(WORDS);
    }
}

WordCountTokenizer.java用于切分句子，其内容如下：

package com.xju.wc;
import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;
 
public class WordCountTokenizer implements FlatMapFunction<String, Tuple2<String,Integer>>{
   
    public WordCountTokenizer(){
   }
    public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
   
        String[] tokens = value.toLowerCase().split("\\W+");
        int len = tokens.length;
        for(int i = 0; i<len;i++){
   
            String tmp = tokens[i];
            if(tmp.length()>0){
   
                out.collect(new Tuple2<String, Integer>(tmp,Integer.valueOf(1))