read and write csv file

pom依赖

        <dependency>
            <groupId>net.sourceforge.javacsv</groupId>
            <artifactId>javacsv</artifactId>
            <version>2.0</version>
        </dependency>

通用类

public class CsvUtils {
    private static final Charset DEFAULT_CHARSET = Charset.forName("GB2312");

    /**
     * 读取Json String
     * @param filePath
     * @param fields
     * @return
     * @throws IOException
     */
    public static String read(String filePath, String[] fields) throws IOException {
        return read(filePath, fields, DEFAULT_CHARSET);
    }

    /**
     * 读取Json String
     * @param filePath
     * @param fields Json key（按csv表头格式传入对应的列字段名）
     * @param charset
     * @return
     * @throws IOException
     */
    public static String read(String filePath, String[] fields, Charset charset) throws IOException {
        // 创建CSV读对象
        @Cleanup
        CsvReader csvReader = new CsvReader(filePath, ',', charset);
        // 读表头
        csvReader.readHeaders();
        // 获取表头
        String[] headers = csvReader.getHeaders();

        if(fields == null || fields.length <= 0) {
            fields = csvReader.getHeaders();
        }

        StringBuilder sb = new StringBuilder();
        sb.append("[");
        while (csvReader.readRecord()) {
            sb.append("{");
            for (int i = 0; i < fields.length; i++) {
                sb.append("\"").append(fields[i]).append("\":\"").append(csvReader.get(headers[i])).append("\"");
                if (i < fields.length - 1) {
                    sb.append(",");
                }
            }
            sb.append("},");
        }
        if (sb.lastIndexOf(",") > 0) {
            sb.deleteCharAt(sb.lastIndexOf(",")).append("]");
        }
        return sb.toString();
    }

    /**
     * 写入csv
     * @param filePath
     * @param headers
     * @param content
     * @throws IOException
     */
    public static void write(String filePath, String[] headers, List<String[]> content) throws IOException {
        write(filePath, headers, content, DEFAULT_CHARSET);
    }

    /**
     * 写入csv文件
     * @param filePath 写入路径
     * @param headers  表头
     * @param content  内容
     * @param charset  编码
     * @throws IOException
     */
    public static void write(String filePath, String[] headers, List<String[]> content, Charset charset) throws IOException {
        // 创建CSV写对象
        @Cleanup
        CsvWriter csvWriter = new CsvWriter(filePath, ',', charset);
        // 写表头
        csvWriter.writeRecord(headers);
        // 写行数据
        int i = 0;
        for (String[] rowTxt : content) {
            i++;
            csvWriter.writeRecord(rowTxt);
            if (i == 10000) {
                csvWriter.flush();
                i = 0;
            }
        }
        csvWriter.flush();
    }
}

读取/写入数据

    private static final String[] header = {"列1", "列2", "列3", "列4", "列5", "列6", "列7", "列8", "列9", "列10", "列11"};
    private static final String[] headerCol = {"id", "col1", "col2", "col3", "col4", "col5", "col6", "col7", "col8", "col9", "col10"};

    public static void writeCsvData(String filePath, Integer count) throws IOException {
        long l = System.currentTimeMillis();

        // 表头
        String[] headers = header;
        List<DataDemo> dataList = getDataList(count);
        List<String[]> dataRows = new ArrayList<>(dataList.size());
        // 添加表头
        for (DataDemo data : dataList) {
            String[] rowTxt = new String[]{String.valueOf(data.getId()), data.getCol1(), data.getCol2(), data.getCol3(),
 data.getCol4(), data.getCol5(), data.getCol6(), data.getCol7(), data.getCol8(), data.getCol9(), data.getCol10()};
            dataRows.add(rowTxt);
        }
        CsvUtils.write(filePath, headers, dataRows, Charset.forName("GB2312"));

        System.out.println("write csv data:" + dataRows.size() + ",cost:" + (System.currentTimeMillis() - l));
    }

    public static void readCsvData(String filePath) throws IOException {
        long l = System.currentTimeMillis();

        String[] fields = headerCol;
        String read = CsvUtils.read(filePath, fields);
        List<DataDemo> infoList = JSON.parseArray(read, DataDemo.class);

        System.out.println("read csv data:" + infoList.size() + ",cost:" + (System.currentTimeMillis() - l));
    }