Java 导出 CSV 文件

来源：恒创科技编辑：恒创科技编辑部

2024-01-23 18:54:59

首先第一步导入坐标

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-csv</artifactId>
    <version>1.6</version>
</dependency>

第二布
引入工具类说明下因为这个工具类用到是Listj集合
我就顺带吧实体类和map 之间的转换也说了

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.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
 
import java.io.*;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
 
/**
 * 导出至csv文件
 * */
public class CsvUtil {
    //CSV文件分隔符
    private final static String NEW_LINE_SEPARATOR="\n";
    /** CSV文件列分隔符 */
    private static final String CSV_COLUMN_SEPARATOR = ",";
    /** CSV文件列分隔符 */
    private static final String CSV_RN = "\r\n";
 
    /**写入csv文件
     * @param headers 列头
     * @param data 数据内容
     * @param filePath 创建的csv文件路径
     * @throws IOException **/
    public static void writeCsvWithHeader(String[] headers, List<Object[]> data, String filePath) {
        //初始化csvformat
        CSVFormat format = CSVFormat.DEFAULT.withHeader(headers);
        try {
            //根据路径创建文件，并设置编码格式
            FileOutputStream fos = new FileOutputStream(filePath);
            OutputStreamWriter osw = new OutputStreamWriter(fos, "GBK");
            //创建CSVPrinter对象
            CSVPrinter printer = new CSVPrinter(osw, format);
 
            if(null!=data){
                //循环写入数据
                for(Object[] lineData:data){
                    printer.printRecord(lineData);
                }
            }
            printer.flush();
            printer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
 
    /**写入csv文件
     * @param headers 列头
     * @param data 数据内容
     * @param filePath 创建的csv文件路径
     * @throws IOException **/
    public static void writeCsvWithRecordSeparator(Object[] headers, List<Object[]> data, String filePath){
        //初始化csvformat
        CSVFormat format = CSVFormat.DEFAULT.withRecordSeparator(NEW_LINE_SEPARATOR);
        try {
            //根据路径创建文件，并设置编码格式
            FileOutputStream fos = new FileOutputStream(filePath);
            OutputStreamWriter osw = new OutputStreamWriter(fos, "GBK");
            //创建CSVPrinter对象
            CSVPrinter printer = new CSVPrinter(osw,format);
            //写入列头数据
            printer.printRecord(headers);
 
            if(null!=data){
                //循环写入数据
                for(Object[] lineData:data){
                    printer.printRecord(lineData);
                }
            }
            printer.flush();
            printer.close();
            System.out.println("CSV文件创建成功,文件路径:"+filePath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
 
    /**
     * @filePath 文件路径
     */
    public static List<CSVRecord> readCsvParse(String filePath){
        List<CSVRecord> records = new ArrayList<>();
        try {
            FileInputStream in = new FileInputStream(filePath);
            BufferedReader reader = new BufferedReader (new InputStreamReader(in,"GBK"));
            CSVParser parser = CSVFormat.EXCEL.parse(reader);
            records = parser.getRecords();
            parser.close();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            return records;
        }
    }
 
    /**
     * 自定义字段
     * @filePath 文件路径
     */
    public static List<CSVRecord> readCsvParseWithHeader(String filePath,String[] headers){
        List<CSVRecord> records = new ArrayList<>();
        try {
            FileInputStream in = new FileInputStream(filePath);
            BufferedReader  reader = new BufferedReader (new InputStreamReader(in,"GBK"));
            CSVParser parser = CSVFormat.EXCEL.withHeader(headers).parse(reader);
            records = parser.getRecords();
            /*for (CSVRecord record : parser.getRecords()) {
                System.out.println(record.get("id") + ","
                        + record.get("name") + ","
                        + record.get("code"));
            }*/
            parser.close();
        }catch (IOException e){
            e.printStackTrace();
        }finally {
            return records;
        }
    }
 
    /**
     * 导出至多个csv文件
     * */
    public void writeMuti() throws InterruptedException {
        ExecutorService executorService = Executors.newFixedThreadPool(3);
        CountDownLatch doneSignal = new CountDownLatch(2);
 
        List<Map<String, String>> recordList = new ArrayList<>();
 
        executorService.submit(new CsvExportThread("E:/0.csv", recordList, doneSignal));
        executorService.submit(new CsvExportThread("E:/1.csv", recordList, doneSignal));
 
        doneSignal.await();
        System.out.println("Finish!!!");
    }
 
 
    /**
     * @param colNames 表头部数据
     * @param dataList 集合数据
     * @param mapKeys 查找的对应数据
     */
    public static ByteArrayOutputStream doExport(String[] colNames, String[] mapKeys, List<Map> dataList) {
        try {
            StringBuffer buf = new StringBuffer();
 
            // 完成数据csv文件的封装
            // 输出列头
            for (int i = 0; i < colNames.length; i++) {
                buf.append(colNames[i]).append(CSV_COLUMN_SEPARATOR);
            }
            buf.append(CSV_RN);
 
            if (null != dataList) { // 输出数据
                for (int i = 0; i < dataList.size(); i++) {
                    for (int j = 0; j < mapKeys.length; j++) {
                        buf.append(dataList.get(i).get(mapKeys[j])).append(CSV_COLUMN_SEPARATOR);
                    }
                    buf.append(CSV_RN);
                }
            }
            // 写出响应
            ByteArrayOutputStream os = new ByteArrayOutputStream();
            //OutputStream os = new ByteArrayOutputStream();
            os.write(buf.toString().getBytes("GBK"));
            os.flush();
            os.close();
            return os;
        } catch (Exception e) {
            LogUtils.error("doExport错误...", e);
            e.printStackTrace();
        }
        return null;
    }
 
    public static HttpHeaders setCsvHeader(String fileName) {
        HttpHeaders headers = new HttpHeaders();
        try {
            // 设置文件后缀
            SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
            String filename = new String(fileName.getBytes("gbk"), "iso8859-1") + sdf.format(new Date()) + ".csv";
            headers.add("Pragma", "public");
            headers.add("Cache-Control", "max-age=30");
            headers.add("Content-Disposition", "attachment;filename="+filename);
            headers.setContentType(MediaType.valueOf("application/vnd.ms-excel;charset=UTF-8"));
        }catch (Exception e){
            e.printStackTrace();
        }
        return headers;
    }
 
}

第三部
controller 层

package com.example.demo.controller;

import com.example.demo.service.DemoService;
import com.example.demo.util.CsvUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/demo")
public class DemoController {
 
    @Autowired
    private DemoService demoService;
 
    @RequestMapping("/exportCsv")
    public ResponseEntity<byte[]> exportCsv(){
        //设置excel文件名
        String fileName="用户表";
        //设置HttpHeaders，设置fileName编码，排除导出文档名称乱码问题
        HttpHeaders headers = CsvUtil.setCsvHeader(fileName);
        byte[] value = null;
        try {
            //获取要导出的数据
            value = this.demoService.exportCsv();
        }catch (Exception e){
            e.printStackTrace();
        }
        return new ResponseEntity<byte[]>(value,headers, HttpStatus.OK);
    }
}

第四步
service 接口

package com.example.demo.service;

public interface DemoService {
    /*导出csv文件*/
    byte[] exportCsv();
}

第五步
service 实现类

package com.example.demo.service.impl;

import com.example.demo.pojo.User;
import com.example.demo.service.DemoService;
import com.example.demo.util.CsvUtil;
import org.apache.commons.beanutils.BeanUtils;
import org.springframework.stereotype.Service;

import java.io.ByteArrayOutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

@Service
public class DemoServiceImpl implements DemoService {
 
    @Override
    public byte[] exportCsv() {
        byte[] content = null;
        try {
            String[] sTitles = new String[]{"名称","年龄","性别"};
            String[] mapKeys = new String[]{"name","age","sex"};
            List<Map> dataList = new ArrayList<>();
            //数据
            for (int i = 0; i < 10; i++) {
                User user = new User("小明" + i, i, "男" + i);
                Map map = BeanUtils.describe(user);
                dataList.add(map);
            }

            ByteArrayOutputStream os = CsvUtil.doExport(sTitles,mapKeys,dataList);
            content = os.toByteArray();
        }catch (Exception e){
            e.printStackTrace();
        }
        return content;
    }
}

补充 :
对象和map 互相转换
坐标

<dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.9.3</version>
        </dependency>

用到的工具类
BeanUtils
1. bean(实体类)转Map
例子:

Person person=new Person();  
        person1.setName("张三");  
        person1.setSex("不男不女");  
        Map<String, Object> map=null;
        
        map = BeanUtils.describe(person1);

2. map转bean(实体类)
  例子:     估计谁没事也不会用map 转bean   可能是我见识短了

/** 
     * Map转换层Bean，使用泛型免去了类型转换的麻烦。
     * @param <T> 
     * @param map   
     * @param class1 
     * @return 
     */  
    public static <T> T map2Bean(Map<String, String> map, Class<T> class1) {  
        T bean = null;  
        try {  
            bean = class1.newInstance();  
            BeanUtils.populate(bean, map);  
        } catch (Exception e) {  
            e.printStackTrace();  
        }
        return bean;  
    }