grammar CSV;

file : hdr row+ ;

hdr : row ;

row : field (',' field)* '\r'? '\n' ;

field

: TEXT # text

| STRING # string

| # empty

;

TEXT : ~[,\n\r"]+ ;

STRING : '"' ('""'|~'"')* '"' ;

import org.antlr.v4.runtime.CharStream;

import org.antlr.v4.runtime.CharStreams;

import org.antlr.v4.runtime.CommonTokenStream;

import org.antlr.v4.runtime.tree.ParseTreeWalker;

import java.io.*;

import java.util.ArrayList;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Map;

class Loader extends CSVBaseListener {

    public static final String EMPTY = "";

    /**

     * Load a list of row maps that map field name to value

     */

    List<Map<String, String>> rows = new ArrayList<Map<String, String>>();

    /**

     * List of column names

     */

    List<String> header;

    /**

     * Build up a list of fields in current row

     */

    List<String> currentRowFieldValues;

    public void exitString(CSVParser.StringContext ctx) {

        currentRowFieldValues.add(ctx.STRING().getText());

    }

    public void exitText(CSVParser.TextContext ctx) {

        currentRowFieldValues.add(ctx.TEXT().getText());

    }

    public void exitEmpty(CSVParser.EmptyContext ctx) {

        currentRowFieldValues.add(EMPTY);

    }

    public void exitHdr(CSVParser.HdrContext ctx) {

        header = new ArrayList<String>();

        header.addAll(currentRowFieldValues);

    }

    public void enterRow(CSVParser.RowContext ctx) {

        currentRowFieldValues = new ArrayList<String>();

    }

    public void exitRow(CSVParser.RowContext ctx) {

        // If this is the header row, do nothing

        // if ( ctx.parent instanceof CSVParser.HdrContext ) return; OR:

        if ( ctx.getParent().getRuleIndex() == CSVParser.RULE_hdr ) return;

        // It's a data row

        Map<String, String> m = new LinkedHashMap<String, String>();

        int i = 0;

        for (String v : currentRowFieldValues) {

            m.put(header.get(i), v);

            i++;

        }

        rows.add(m);

    }

}

public class LoadCSV {

    public static void main(String[] args) throws IOException {

        /*

        新的版本已经抛弃

        File csvFile = new File("F:\\IDEA_JAVA\\CSV\\test\\test.csv");

        InputStream fi = new FileInputStream(csvFile);

        ANTLRInputStream inputStream = new ANTLRInputStream(fi);

        CSVLexer lexer = new CSVLexer(inputStream);

        CommonTokenStream tokenStream = new CommonTokenStream(lexer);

        CSVParser parser = new CSVParser(tokenStream);

        ParseTreeWalker walker = new ParseTreeWalker();

        Loader loader = new Loader();

        walker.walk(loader, parser.file());

        System.out.println(loader.rows);

        */

        String path = "F:\\IDEA_JAVA\\CSV\\test\\test.csv";

        CharStream inputStream = CharStreams.fromFileName(path);

        CSVLexer lexer = new CSVLexer(inputStream);

        CommonTokenStream tokenStream = new CommonTokenStream(lexer);

        CSVParser parser = new CSVParser(tokenStream);

        ParseTreeWalker walker = new ParseTreeWalker();

        Loader loader = new Loader();

        walker.walk(loader, parser.file());

        System.out.println(loader.rows);

    }

}