Spring SpEL在Flink中的应用-与FlatMap结合实现数据动态计算

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前言

SpEL表达式与Flink FlatMapFunction或MapFunction结合可以实现基于表达式的简单动态计算。有关SpEL表达式的使用请参考Spring SpEL在Flink中的应用-SpEL详解。
可以将计算表达式放入数据库，对数据进行计算处理，从而实现只需修改表达式不用修改Flink代码就能实现数据计算。对于基于Flink进行数据计算平台建设会起到事半功倍的效果。

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一、POM依赖

首先在 pom.xml 中加入依赖：

<dependency>
   <groupId>org.springframeworkgroupId>
   <artifactId>spring-expressionartifactId>
   <version>5.2.0.RELEASEversion>
dependency>​

二、主函数代码示例

import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.types.Row;

import java.text.SimpleDateFormat;

public class FlinkSpelFilterDemo {
    public static void main(String[] args) throws Exception {
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        Row row=Row.of("张三","001",getTimestamp("2016-10-24 21:59:06"),23);
        Row row2=Row.of("张三","002",getTimestamp("2016-10-24 21:50:06"),33);
        Row row3=Row.of("张三","003",getTimestamp("2016-10-24 21:51:06"),43);
        Row row4=Row.of("李四","004",getTimestamp("2016-10-24 21:50:56"),13);
        Row row5=Row.of("李四","005",getTimestamp("2016-10-24 00:48:36"),53);
        Row row6=Row.of("李四","006",getTimestamp("2016-10-24 00:48:36"),34);
        Row row7=Row.of("李四","007",getTimestamp("2016-10-24 00:48:36"),23);
        Row row8=Row.of("李四","008",getTimestamp("2016-10-24 00:48:36"),26);
        Row row9=Row.of("李四","009",getTimestamp("2016-10-24 00:48:36"),63);

        DataStreamSource<Row> source =env.fromElements(row,row2,row3,row4,row5,row6,row7,row8,row9);
        //spel表达式 
        //json串数据略
        ...................
        JSONObject spelConfig=".................................";
        SingleOutputStreamOperator<Row> stream = source.flatmap(new FlatMapExprFunction (spelConfig));
        stream .print();
        env.execute();
    }
    private static java.sql.Timestamp getTimestamp(String str) throws Exception {
//		String string = "2016-10-24 21:59:06";
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        java.util.Date date=sdf.parse(str);
        java.sql.Timestamp s = new java.sql.Timestamp(date.getTime());
        return s;
    }

三、RichFlatMapFunction实现

import org.apache.commons.lang3.StringUtils;
import org.apache.flink.api.common.functions.RichFlatMapFunction;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.types.Row;
import org.apache.flink.util.Collector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author gaowc
 * 基于表达式计算的flatmap
 */
public class FlatMapExprFunction extends RichFlatMapFunction<Row, Row> {
    private static final Logger logger = LoggerFactory.getLogger(FlatMapExprFunction.class);
    /**
     * 列名和列的索引map key:列名 value:列索引
     */
    private Map<String, Integer> columnIndexMap;
    /**
     * key:输出字段名 value：表达式对象
     */
    private transient Map<String,Expression> expMap;
    private Integer size;
    private List<JSONObject> outputColumnList;
    public FlatMapExprFunction(JSONObject conf){
        List<JSONObject > columnList = conf.getList(Constants.COLUMN);
        columnIndexMap = TransformUtil.getColumnIndexMap(columnList);
        List<JSONObject > outputColumns = conf.getList(Constants.OUTPUT_COLUMN);
        //将表达式中的占位符替换为row.getField(x)
        size = outputColumns.size();
        outputColumnList = new ArrayList<>();
        for (JSONObject col:outputColumns) {
            String expr = col.getString("expr");
            if(StringUtils.isNotBlank(expr)){
                ExprTokenParser tokenParser = new ExprTokenParser("#{","}",new ColumnTokenHandler(columnIndexMap));
                String newExpr=tokenParser.parse(expr);
                logger.info("expr: {} newExpr {}",expr,newExpr);
                col.set("expr",newExpr);
            }
            outputColumnList.add(col);
        }
    }
    @Override
    public void open(Configuration parameters) throws Exception {
        super.open(parameters);
        expMap = new HashMap<>();
        //初始化expMap
        for (JSONObject col:outputColumnList) {
            logger.info("open col:{}",col);
            String expr = col.getString("expr");
            if(StringUtils.isNotBlank(expr)){
                SpelExpressionParser parser = new SpelExpressionParser();
                Expression expression = parser.parseExpression(expr);
                expMap.put(col.getString(Constants.COLUMN_NAME),expression);
            }
        }
    }
    @Override
    public void flatMap(Row row, Collector<Row> collector) throws Exception {
        Row outputRow=new Row(size);
        //注册自定义函数
        StandardEvaluationContext conetxt = new StandardEvaluationContext(new SpelMethodUtil());
        conetxt.setVariable("row",row);
        for (int i = 0; i < size; i++) {
            JSONObject col = outputColumnList.get(i);
            String colName = col.getString(Constants.COLUMN_NAME);
            Expression expression = expMap.get(colName);
            Object value = null;
            if(expression!=null){
                value = expression.getValue(conetxt);
                if(value!=null){
                    logger.info("expression.getValue :{}  class {}",value,value.getClass() );
                }
            }else{
                value=row.getField(columnIndexMap.get(colName));
            }
            outputRow.setField(i,value);
        }
        collector.collect(outputRow);
    }

}

自定义函数类

import org.apache.commons.lang3.StringUtils;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class SpelMethodUtil {
    public static final String TIMESTAMP_FORMAT = "yyyy-MM-dd HH:mm:ss";
    public static final String DATE_FORMAT = "yyyy-MM-dd";
    public static final String TIME_FORMAT = "HH:mm:ss";

    public static Integer compareDate(Date date, String strDate){
        Integer result;
        if(date==null&& StringUtils.isBlank(strDate)){
            return 0;
        }else{
            if(date==null || StringUtils.isBlank(strDate)){
                return -2;
            }
        }
        String trimDate=strDate.trim();
        String format = findFormat(trimDate);
        Date date2 = stringToDate(trimDate, format);
        result=date.compareTo(date2);
        return result;
    }
    public static Integer compareDate(Date first, Date second){
        if(first==null&& second==null){
            return 0;
        }else{
            if(first==null || second==null){
                return -2;
            }
        }
        return first.compareTo(second);
    }
    public static Date stringToDate(String dateStr,String format){
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        Date date=null;
        try {
            date= sdf.parse(dateStr);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return date;
    }
    /**
     * 查找与输入的字符型日期相匹配的format
     * @param strDate
     * @return
     */
    public static String findFormat(String strDate){
        String result=null;
        String trimDate=strDate.trim();
        int len=trimDate.length();
        String dateRegex = "";
        if(len==TIMESTAMP_FORMAT.length()){
            dateRegex = "^\\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2}$";
            if(trimDate.matches(dateRegex)){
                result=TIMESTAMP_FORMAT;
            }
        }else if(len==DATE_FORMAT.length()){
            dateRegex = "^\\d{4}-\\d{2}-\\d{2}$";
            if(trimDate.matches(dateRegex)){
                result=DATE_FORMAT;
            }
        }else if(len==TIME_FORMAT.length()){
            dateRegex = "^\\d{2}:\\d{2}:\\d{2}$";
            if(trimDate.matches(dateRegex)){
                result=TIME_FORMAT;
            }
        }else{
            throw  new RuntimeException("不可识别的日期格式！"+strDate);
        }
        return result;
    }
    public static Integer addAge(Integer age){
        return age+4;
    }
}

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总结

以上只是简单的示例，在实际应用中可以将运算表达式放到数据库，将计算规则放入缓存定时刷新。大家可以根据实际需求进行扩展。