新建工程，引入pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.flink</groupId>
    <artifactId>Flink_Demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <flink.version>1.13.0</flink.version>
        <java.version>1.8</java.version>
        <scala.binary.version>2.12</scala.binary.version>
        <slf4j.version>1.7.30</slf4j.version>
    </properties>


    <dependencies>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-java</artifactId>
            <version>${flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients_${scala.binary.version}</artifactId>
            <version>${flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4g</groupId>
            <artifactId>slf4g-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4g</groupId>
            <artifactId>slf4g-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-to-slf4j</artifactId>
            <version>2.14.0</version>
        </dependency>


    </dependencies>


    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.0.0</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>

            </plugin>
        </plugins>
    </build>


</project>

批处理代码

package com.atguigu.wc;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;



public class WordCount {
    public static void main(String[] args) throws Exception{

        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
        DataSet<String> stringDataSource = env.readTextFile("D:\\develop\\idea_workspace\\Flink_Demo_SGG\\input\\wordcount.txt");
        DataSet<Tuple2<String,Long>> resultSet = stringDataSource.flatMap(new MyFlatMapper()).groupBy(0).sum(1);
        resultSet.print();
    }

    static class MyFlatMapper implements FlatMapFunction<String, Tuple2<String,Long>> {
        public void flatMap(String value, Collector<Tuple2<String, Long>> out) throws Exception {
            String[] words = value.split(" ");
            //words遍历
            for (String word:words){
                out.collect(new Tuple2<String, Long>(word, (long) 1));
            }

        }

    }
}

文件准备：在工程下新建文件夹input，新建文件wordcount.txt

hello word
python java flink
hello python java
java

运行结果：

有界流处理代码

package com.atguigu.wc;

import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

public class WordCount_Stream {
    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        DataStream<String> stringDataSource = env.readTextFile("D:\\develop\\idea_workspace\\Flink_Demo_SGG\\input\\wordcount.txt");

        SingleOutputStreamOperator<Tuple2<String, Long>> resultStream = stringDataSource.flatMap(new WordCount.MyFlatMapper()).keyBy(0).sum(1);
        resultStream.print();
        env.execute();
    }
}

运行结果：

无界流处理代码（需要开启cocket连接）

package com.atguigu.wc;

import org.apache.flink.api.common.typeinfo.Types;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.KeyedStream;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

public class WordCount_Stream_socket {
    public static void main(String[] args) throws Exception {

        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
//        DataStreamSource<String> dataStreamSource = env.socketTextStream("10.22.82.120", 7777);
        DataStreamSource<String> dataStreamSource = env.socketTextStream("10.30.202.21", 7777);

        SingleOutputStreamOperator<Tuple2<String, Long>> returns = dataStreamSource.flatMap(new WordCount.MyFlatMapper()).returns(Types.TUPLE(Types.STRING, Types.LONG));


        KeyedStream<Tuple2<String, Long>, String> stream = returns.keyBy(data -> data.f0);


        SingleOutputStreamOperator<Tuple2<String, Long>> sum = stream.sum(1);
        sum.print();

        env.execute();


    }

}