Flink(5)读取数据源的几种方式

执行环境

创建一个执行环境，表示当前执行程序的上下文，如果程序是独立调用的则此方法返回本地执行环境，如果从命令行客户端调用程序提交到集群，则此方法返回此集群的执行环境，也就是是说，getExecutionEnvironment(),会根据查询运行的方式决定返回什么样的运行环境。是最常用的一种创建执行环境的方式。

# 流处理环境
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
#批处理
ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

1.读取的数据源-Elements

DataStreamSource integerDataStreamSource = env.fromElements(1, 2, 2, 5, 44);

2.读取的数据源-Collection

public class SensorReading {

    private String id;
    private Long timestamp;
    private Double temperature;

    public SensorReading() {
    }

    public SensorReading(String id, Long timestamp, Double temperature) {
        this.id = id;
        this.timestamp = timestamp;
        this.temperature = temperature;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public Long getTimestamp() {
        return timestamp;
    }

    public void setTimestamp(Long timestamp) {
        this.timestamp = timestamp;
    }

    public Double getTemperature() {
        return temperature;
    }

    public void setTemperature(Double temperature) {
        this.temperature = temperature;
    }

    @Override
    public String toString() {
        return "SensorReading{" +
                "id='" + id + '\'' +
                ", timestamp=" + timestamp +
                ", temperature=" + temperature +
                '}';
    }

DataStreamSource sensorDataStream = env.fromCollection(Arrays.asList(
                new SensorReading("sensor_1", 1547718199L, 35.8),
                new SensorReading("sensor_6", 1547718201L, 15.8),
                new SensorReading("sensor_7", 1547718202L, 37.8),
                new SensorReading("sensor_10", 1547718203L, 38.8)
        ));

3.读取的数据源-File

 //从文件读取
DataStreamSource stringDataStreamSource = env.readTextFile("/path/to/hello.txt");

4.从socket文本流读取数据

DataStream inputDataStream = env.socketTextStream(localhost,7777);

最终执行

 sensorDataStream.print("sensor");
 integerDataStreamSource.print("int");
 stringDataStreamSource.print("file");

 env.execute("my job name");