java读写csv文件的共通方法

读取CSV文件的常见方法有两种：使用Java内置的Scanner类和使用第三方库OpenCSV。

使用Scanner类读取CSV文件的示例代码如下：

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class CsvReader {

    public static void main(String[] args) {
        File file = new File("input.csv");

        try {
            Scanner scanner = new Scanner(file);

            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                String[] fields = line.split(",");

                for (String field : fields) {
                    System.out.print(field + "\t");
                }

                System.out.println();
            }

            scanner.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

}

使用OpenCSV库读取CSV文件的示例代码如下：

import com.opencsv.CSVReader;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class CsvReader {

    public static void main(String[] args) {
        String csvFile = "input.csv";

        try {
            CSVReader reader = new CSVReader(new FileReader(csvFile));
            String[] line;

            while ((line = reader.readNext()) != null) {
                for (String field : line) {
                    System.out.print(field + "\t");
                }

                System.out.println();
            }

            reader.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

写入CSV文件的常见方法也有两种：使用Java内置的PrintWriter类和使用第三方库OpenCSV。

使用PrintWriter类写入CSV文件的示例代码如下：

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

public class CsvWriter {

    public static void main(String[] args) {
        File file = new File("output.csv");

        try {
            PrintWriter writer = new PrintWriter(file);

            List<String[]> lines = new ArrayList<>();
            lines.add(new String[]{"Name", "Age", "Gender"});
            lines.add(new String[]{"John", "30", "Male"});
            lines.add(new String[]{"Mary", "25", "Female"});

            for (String[] line : lines) {
                for (int i = 0; i < line.length; i++) {
                    writer.print(line[i]);

                    if (i < line.length - 1) {
                        writer.print(",");
                    }
                }

                writer.println();
            }

            writer.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

}

使用OpenCSV库写入CSV文件的示例代码如下：

import com.opencsv.CSVWriter;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class CsvWriter {

    public static void main(String[] args) {
        String csvFile = "output.csv";

        try {
            CSVWriter writer = new CSVWriter(new FileWriter(csvFile));

            List<String[]> lines = new ArrayList<>();
            lines.add(new String[]{"Name", "Age", "Gender"});
            lines.add(new String[]{"John", "30", "Male"});
            lines.add(new String[]{"Mary", "25", "Female"});

            writer.writeAll(lines);

            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}