Java による csv ファイルの読み書き (オブジェクトデータへの自動抽出と変換)

/**
     * Read a csv file (not too big for a one-time read)
     *
     * @param filePath file path
     * @param headers csv column headers
     * @param tClass Return the type of the object
     * @return CSVRecord list
     * @throws BizException
     **/
    public static 
 List
 readCSV(String filePath, String[] headers, Class
 tClass) {
        // Create CSVFormat
        CSVFormat format = CSVFormat.DEFAULT.withHeader(headers);
        // Get the PropertyDescriptor of the object
        List
 tList = new ArrayList<>();
        try {
            Map
5. Testing
public static void main(String[] args) throws Exception {
        String[] fileHeader = {"name", "sex"};
        // test write
        List
 list = new ArrayList<>();
        for (int i = 0; i < 1000000; i++) {
            MsgResponse msgResponse = new MsgResponse();
            msgResponse.setCode("Name44444888");
            msgResponse.setMsg("Gender44444488");
            list.add(msgResponse);
        }
        long writeTimeStart = System.currentTimeMillis();
        CsvUtils.writeCsv(list, fileHeader, "d:\\workbook.csv");
        logger.info("writeTime:" + (System.currentTimeMillis() - writeTimeStart));
// test read
        long readTimeStart = System.currentTimeMillis();
        List
 m = CsvUtils.readCSV("d:\workbook.csv", fileHeader, MsgResponse.class);
        logger.info("ReadTime:" + (System.currentTimeMillis() - readTimeStart));
// for (MsgResponse msgResponse : m) {
// logger.info(msgResponse.getCode() + " " + msgResponse.getMsg());
// }
    }

Results


 The generated csv may have encoding issues when opened in excel, just turn it, or use the text tool to open it
14:46:05.847 [main] INFO CsvUtils.class - write time: 593
14:46:07.237 [main] INFO CsvUtils.class - Read time: 1390

Process finished with exit code 0

The file is about 30M


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 The full source code except for the annotation class, which is a name field
package com.store.common.utils;

import com.google.common.collect.Maps;
import com.store.common.annotation.CsvField;
import com.store.common.exception.BizException;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.csv.CSVRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.beans;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.*;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
Map; import java.util;

/**
 * csv file read/write tool class
 *
 * @author by YangLD
 * @date 2018/7/10
 */
public class CsvUtils {

    private static final Logger logger = LoggerFactory.getLogger("CsvUtils.class");

    /**
     * Write csv file (write at once. Data should not be too large)
     *
     * @param objectList object
     * @param fileHeader header description
     * @param fileName File name (no .csv suffix)
     * @return File file
     * @throws BizException Exception
     */
    public static File writeCsv(List
 objectList, String[] fileHeader, String fileName) {
        // explicitly configure the Header of the CSV file here, and then set the Header to be skipped (otherwise the header will be treated as a record when reading)
        CSVFormat format = CSVFormat.DEFAULT.withHeader(fileHeader).withRecordSeparator("\n");
        // This is a locator to determine where in the records array the data for a field should be placed
        Map
 List
 readCSV(String filePath, String[] headers, Class
 tClass) {
        // Create CSVFormat
        CSVFormat format = CSVFormat.DEFAULT.withHeader(headers);
        // Get the PropertyDescriptor of the object
        List
 tList = new ArrayList<>();
        try {
            Map
 list = new ArrayList<>();
        for (int i = 0; i < 1000; i++) {
            list.add(new TargetObject("Name"+i,""+i+100));
        }
        long writeTimeStart = System.currentTimeMillis();
        CsvUtils.writeCsv(list, fileHeader, "d:\\write.csv");
        logger.info("writeTime:" + (System.currentTimeMillis() - writeTimeStart));
// test read
        long readTimeStart = System.currentTimeMillis();
        List
 targetObjectList = CsvUtils.readCSV("d:\write.csv", fileHeader, TargetObject.class);
        logger.info("ReadTime:" + (System.currentTimeMillis() - readTimeStart));
        for (TargetObject targetObject : targetObjectList) {
            System.out.println(targetObject.getName() + " : " + targetObject.getAge());
        }
    }


    /** targetObject */
    public static class TargetObject{

        public TargetObject() {
        }

        public TargetObject(String name, String age) {
            this.name = name;
            this.age = age;
        }

        @CsvField(name = "name")
        private String name;
        @CsvField(name = "age")
        private String age;

        public String getAge() {
            return age;
        }

        public void setAge(String age) {
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
}