前言

  由於在最近的專案中使用Excel匯入和匯出較為頻繁，以此篇部落格作為記錄，方便日後查閱。本文前臺頁面將使用layui，來演示對Excel檔案匯入和匯出的效果。本文程式碼已上傳至我的gitHub，歡迎訪問，地址：https://github.com/rename123/excel-demo

準備工作

1. 新增操作Excel的有關依賴，如下：

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.13</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.13</version>
        </dependency>
 

  說明：由於我的專案是使用的maven管理，所以通過如上方式新增依賴，如果是通過gradle構建的專案，請按如下方式匯入專案依賴：

implementation group: 'org.apache.poi', name: 'poi-ooxml', version: '3.17'

2. 自定義註解，用來表示實體類中的屬性在Excel中的標題、位置等

package com.reminis.exceldemo.annotation;

import java.lang.annotation.*;

/**
 * 自定義實體類所需要的bean(Excel屬性標題、位置等)
 */
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ExcelColumn {

    /**
     * Excel標題
     * @return
     */
    String value() default "";

    /**
     * Excel從左往右排列位置
     * @return
     */
    int col() default 0;
}

 

3. 編寫ExcelUtils工具類

package com.reminis.exceldemo.util;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.net.URLEncoder;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import com.reminis.exceldemo.annotation.ExcelColumn;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.lang.BooleanUtils;
import org.apache.commons.lang.CharUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.math.NumberUtils;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.MediaType;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ExcelUtils {

    private final static Logger log = LoggerFactory.getLogger(ExcelUtils.class);

    private final static String EXCEL2003 = "xls";
    private final static String EXCEL2007 = "xlsx";

    public static <T> List<T> readExcel(String path, Class<T> cls, MultipartFile file){

        String fileName = file.getOriginalFilename();
        if (!fileName.matches("^.+\\.(?i)(xls)$") && !fileName.matches("^.+\\.(?i)(xlsx)$")) {
            log.error("上傳檔案格式不正確");
        }
        List<T> dataList = new ArrayList<>();
        Workbook workbook = null;
        try {
            InputStream is = file.getInputStream();
            if (fileName.endsWith(EXCEL2007)) {
//                FileInputStream is = new FileInputStream(new File(path));
                workbook = new XSSFWorkbook(is);
            }
            if (fileName.endsWith(EXCEL2003)) {
//                FileInputStream is = new FileInputStream(new File(path));
                workbook = new HSSFWorkbook(is);
            }
            if (workbook != null) {
                //類對映  註解 value-->bean columns
                Map<String, List<Field>> classMap = new HashMap<>();
                List<Field> fields = Stream.of(cls.getDeclaredFields()).collect(Collectors.toList());
                fields.forEach(
                        field -> {
                            ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                            if (annotation != null) {
                                String value = annotation.value();
                                if (StringUtils.isBlank(value)) {
                                    return;//return起到的作用和continue是相同的 語法
                                }
                                if (!classMap.containsKey(value)) {
                                    classMap.put(value, new ArrayList<>());
                                }
                                field.setAccessible(true);
                                classMap.get(value).add(field);
                            }
                        }
                );
                //索引-->columns
                Map<Integer, List<Field>> reflectionMap = new HashMap<>(16);
                //預設讀取第一個sheet
                Sheet sheet = workbook.getSheetAt(0);

                boolean firstRow = true;
                for (int i = sheet.getFirstRowNum(); i <= sheet.getLastRowNum(); i++) {
                    Row row = sheet.getRow(i);
                    //首行  提取註解
                    if (firstRow) {
                        for (int j = row.getFirstCellNum(); j <= row.getLastCellNum(); j++) {
                            Cell cell = row.getCell(j);
                            String cellValue = getCellValue(cell);
                            if (classMap.containsKey(cellValue)) {
                                reflectionMap.put(j, classMap.get(cellValue));
                            }
                        }
                        firstRow = false;
                    } else {
                        //忽略空白行
                        if (row == null) {
                            continue;
                        }
                        try {
                            T t = cls.newInstance();
                            //判斷是否為空白行
                            boolean allBlank = true;
                            for (int j = row.getFirstCellNum(); j <= row.getLastCellNum(); j++) {
                                if (reflectionMap.containsKey(j)) {
                                    Cell cell = row.getCell(j);
                                    String cellValue = getCellValue(cell);
                                    if (StringUtils.isNotBlank(cellValue)) {
                                        allBlank = false;
                                    }
                                    List<Field> fieldList = reflectionMap.get(j);
                                    fieldList.forEach(
                                            x -> {
                                                try {
                                                    handleField(t, cellValue, x);
                                                } catch (Exception e) {
                                                    log.error(String.format("reflect field:%s value:%s exception!", x.getName(), cellValue), e);
                                                }
                                            }
                                    );
                                }
                            }
                            if (!allBlank) {
                                dataList.add(t);
                            } else {
                                log.warn(String.format("row:%s is blank ignore!", i));
                            }
                        } catch (Exception e) {
                            log.error(String.format("parse row:%s exception!", i), e);
                        }
                    }
                }
            }
        } catch (Exception e) {
            log.error(String.format("parse excel exception!"), e);
        } finally {
            if (workbook != null) {
                try {
                    workbook.close();
                } catch (Exception e) {
                    log.error(String.format("parse excel exception!"), e);
                }
            }
        }
        return dataList;
    }

    private static <T> void handleField(T t, String value, Field field) throws Exception {
        Class<?> type = field.getType();
        if (type == null || type == void.class || StringUtils.isBlank(value)) {
            return;
        }
        if (type == Object.class) {
            field.set(t, value);
            //數字型別
        } else if (type.getSuperclass() == null || type.getSuperclass() == Number.class) {
            if (type == int.class || type == Integer.class) {
                field.set(t, NumberUtils.toInt(value));
            } else if (type == long.class || type == Long.class) {
                field.set(t, NumberUtils.toLong(value));
            } else if (type == byte.class || type == Byte.class) {
                field.set(t, NumberUtils.toByte(value));
            } else if (type == short.class || type == Short.class) {
                field.set(t, NumberUtils.toShort(value));
            } else if (type == double.class || type == Double.class) {
                field.set(t, NumberUtils.toDouble(value));
            } else if (type == float.class || type == Float.class) {
                field.set(t, NumberUtils.toFloat(value));
            } else if (type == char.class || type == Character.class) {
                field.set(t, CharUtils.toChar(value));
            } else if (type == boolean.class) {
                field.set(t, BooleanUtils.toBoolean(value));
            } else if (type == BigDecimal.class) {
                field.set(t, new BigDecimal(value));
            }
        } else if (type == Boolean.class) {
            field.set(t, BooleanUtils.toBoolean(value));
        } else if (type == Date.class) {
            //
            field.set(t, value);
        } else if (type == String.class) {
            field.set(t, value);
        } else if (type == LocalDateTime.class) {
            //String 轉 LocalDateTime
            DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            LocalDateTime dt = LocalDateTime.parse(value, df);
            field.set(t, dt);
        } else {
            Constructor<?> constructor = type.getConstructor(String.class);
            field.set(t, constructor.newInstance(value));
        }
    }

    private static String getCellValue(Cell cell) {
        if (cell == null) {
            return "";
        }
        if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
            if (HSSFDateUtil.isCellDateFormatted(cell)) {
                return HSSFDateUtil.getJavaDate(cell.getNumericCellValue()).toString();
            } else {
                return new BigDecimal(cell.getNumericCellValue()).toString();
            }
        } else if (cell.getCellType() == Cell.CELL_TYPE_STRING) {
            return StringUtils.trimToEmpty(cell.getStringCellValue());
        } else if (cell.getCellType() == Cell.CELL_TYPE_FORMULA) {
            return StringUtils.trimToEmpty(cell.getCellFormula());
        } else if (cell.getCellType() == Cell.CELL_TYPE_BLANK) {
            return "";
        } else if (cell.getCellType() == Cell.CELL_TYPE_BOOLEAN) {
            return String.valueOf(cell.getBooleanCellValue());
        } else if (cell.getCellType() == Cell.CELL_TYPE_ERROR) {
            return "ERROR";
        } else {
            return cell.toString().trim();
        }

    }

    public static <T> void writeExcel(HttpServletRequest request, HttpServletResponse response, List<T> dataList, Class<T> cls){
        Field[] fields = cls.getDeclaredFields();
        List<Field> fieldList = Arrays.stream(fields)
                .filter(field -> {
                    ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                    if (annotation != null && annotation.col() > 0) {
                        field.setAccessible(true);
                        return true;
                    }
                    return false;
                }).sorted(Comparator.comparing(field -> {
                    int col = 0;
                    ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                    if (annotation != null) {
                        col = annotation.col();
                    }
                    return col;
                })).collect(Collectors.toList());

        Workbook wb = new XSSFWorkbook();
        Sheet sheet = wb.createSheet("Sheet1");
        AtomicInteger ai = new AtomicInteger();
        {
            Row row = sheet.createRow(ai.getAndIncrement());
            AtomicInteger aj = new AtomicInteger();
            //寫入頭部
            fieldList.forEach(field -> {
                ExcelColumn annotation = field.getAnnotation(ExcelColumn.class);
                String columnName = "";
                if (annotation != null) {
                    columnName = annotation.value();
                }
                Cell cell = row.createCell(aj.getAndIncrement());

                CellStyle cellStyle = wb.createCellStyle();
                cellStyle.setFillForegroundColor(IndexedColors.WHITE.getIndex());
                cellStyle.setFillPattern(CellStyle.SOLID_FOREGROUND);
                cellStyle.setAlignment(CellStyle.ALIGN_CENTER);

                Font font = wb.createFont();
                font.setBoldweight(Font.BOLDWEIGHT_NORMAL);
                cellStyle.setFont(font);
                cell.setCellStyle(cellStyle);
                cell.setCellValue(columnName);
            });
        }
        if (CollectionUtils.isNotEmpty(dataList)) {
            dataList.forEach(t -> {
                Row row1 = sheet.createRow(ai.getAndIncrement());
                AtomicInteger aj = new AtomicInteger();
                fieldList.forEach(field -> {
                    Class<?> type = field.getType();
                    Object value = "";
                    try {
                        value = field.get(t);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    Cell cell = row1.createCell(aj.getAndIncrement());
                    if (value != null) {
                        if (type == Date.class) {
                            cell.setCellValue(value.toString());
                        } else if (type == LocalDateTime.class){
                            DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
                            cell.setCellValue(df.format((LocalDateTime) value));
                        } else {
                            cell.setCellValue(value.toString());
                        }
                    }
                });
            });
        }
        //凍結窗格
        wb.getSheet("Sheet1").createFreezePane(0, 1, 0, 1);
        //瀏覽器下載excel
        buildExcelDocument(request.getParameter("fileName"),wb,response);
        //生成excel檔案
//        buildExcelFile(".\\default.xlsx",wb);
    }

    /**
     * 瀏覽器下載excel
     * @param fileName
     * @param wb
     * @param response
     */
    private static  void  buildExcelDocument(String fileName, Workbook wb, HttpServletResponse response){
        try {
            response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
            response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(fileName, "utf-8"));
            response.flushBuffer();
            ServletOutputStream outputStream = response.getOutputStream();
            wb.write(outputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 生成excel檔案
     * @param path 生成excel路徑
     * @param wb
     */
    private static  void  buildExcelFile(String path, Workbook wb){

        File file = new File(path);
        if (file.exists()) {
            file.delete();
        }
        try {
            wb.write(new FileOutputStream(file));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

 

4. 定義需要匯出的實體類

package com.reminis.exceldemo.entity;

import com.reminis.exceldemo.annotation.ExcelColumn;
import lombok.Data;
import org.springframework.format.annotation.DateTimeFormat;

import java.math.BigDecimal;
import java.time.LocalDateTime;
import java.util.Date;

@Data
public class Emp {

    @ExcelColumn(value = "員工主鍵id", col = 1)
    private Integer id;

    @ExcelColumn(value = "員工編號",col = 2)
    private String empNo;

    @ExcelColumn(value = "員工名稱",col = 3)
    private String empName;

    @ExcelColumn(value = "員工薪資",col = 4)
    private BigDecimal salary;

    @ExcelColumn(value = "員工職稱",col = 5)
    private String job;

    @ExcelColumn(value = "入職時間",col = 6)
    private LocalDateTime entryTime;
}

Controller層編寫

  在我們做完準備工作後，就可以在我們的Controller層編寫訪問介面了，由於我們沒有連線資料庫，所以我準備了一些測試資料，具體程式碼如下：

package com.reminis.exceldemo.web;

import com.alibaba.fastjson.JSON;
import com.reminis.exceldemo.entity.Emp;
import com.reminis.exceldemo.util.ExcelUtils;
import com.reminis.exceldemo.util.Result;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.math.BigDecimal;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.List;

@CrossOrigin("*")
@RestController
@RequestMapping("/api/test")
public class ExcelController {

    private static final Logger log = LogManager.getLogger(ExcelController.class);

    /**
     * Excel匯出
     * @param response
     */
    @GetMapping("/exportExcel")
    public void exportExcel(HttpServletRequest request,HttpServletResponse response){
        //使用假資料代替從資料庫查出來的需要匯出的資料
        List<Emp> empList = handleRepositoryData();
        long t1 = System.currentTimeMillis();
        ExcelUtils.writeExcel(request,response, empList, Emp.class);
        long t2 = System.currentTimeMillis();
        System.out.println(String.format("write over! cost:%sms", (t2 - t1)));
    }

    /**
     * Excel匯入
     * @param file
     */
    @PostMapping("/readExcel")
    public Result<String> readExcel(@RequestBody MultipartFile file){
        long t1 = System.currentTimeMillis();
        log.info("上傳的檔案："+file);
        List<Emp> list = ExcelUtils.readExcel("", Emp.class, file);
        long t2 = System.currentTimeMillis();
        System.out.println(String.format("read over! cost:%sms", (t2 - t1)));
        list.forEach(
                b -> System.out.println(JSON.toJSONString(b))
        );
        return new Result<>();
    }

    public List<Emp> handleRepositoryData() {
        List<Emp> empList = new ArrayList<>();
        Emp emp;
        for (int i = 1; i<= 10; i++) {
            emp = new Emp();
            emp.setId(i);
            emp.setEmpName("員工" + i);
            emp.setEmpNo((1000 + i) + "");
            emp.setJob("JY" + i);
            emp.setSalary(new BigDecimal(i * 1000 + ""));
            emp.setEntryTime(LocalDateTime.now().minusHours(Long.valueOf(i)));
            empList.add(emp);
        }
        return empList;
    }

    /**
     * 前臺頁面的資料列表
     * @return
     */
    @GetMapping("/getList")
    public Result getList(){
        Result<List<Emp>> result = new Result<>();
        List<Emp> empList = handleRepositoryData();
        result.setData(empList);
        return result;
    }
}

  關於Excel匯入匯出功能的後臺介面，到這裡就寫好了。由於本文示例程式碼中使用了Java8中的新時間，所以在將資料返回給前臺頁面時，我們需要對時間格式進行處理，如下：

package com.reminis.exceldemo.config;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;

@Configuration
public class LocalDateTimeSerializerConfig {

    @Value("${spring.jackson.date-format:yyyy-MM-dd HH:mm:ss}")
    private String pattern;

    @Bean
    public LocalDateTimeSerializer localDateTimeDeserializer() {
        return new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(pattern));
    }

    @Bean
    public Jackson2ObjectMapperBuilderCustomizer jackson2ObjectMapperBuilderCustomizer() {
        return builder -> builder.serializerByType(LocalDateTime.class, localDateTimeDeserializer());
    }

}

  最後就是layui展示頁面了，是一個很簡單上傳下載的列表頁面，程式碼如下：

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
    <title>Excel檔案的匯入匯出測試</title>
    <link rel="stylesheet" href="../layui/css/layui.css">
</head>
<body>

<fieldset class="layui-elem-field layui-field-title" style="margin-top: 30px;">
    <legend style="text-align: center">Excel檔案的匯入匯出測試</legend>
</fieldset>

&emsp;<button type="button" class="layui-btn" id="test3"><i class="layui-icon"></i>匯入Excel</button>&emsp;
<button type="button" class="layui-btn" id="test4"><i class="layui-icon"></i>後臺介面匯出Excel</button>
<button type="button" class="layui-btn" id="test5"><i class="layui-icon"></i>layui匯出選中行的資料</button>
<!-- 你的HTML程式碼 -->
<table class="layui-hide" id="test"></table>


<script src="../layui/layui.js"></script>
<script>
    //一般直接寫在一個js檔案中
    layui.use(['table', 'layer','upload'], function(){
        var table = layui.table
            ,$ = layui.$
            ,layer = layui.layer
            ,upload = layui.upload;

        // layer.msg('Hello World');

        var ins1 = table.render({
            elem: '#test'
            ,url:'http://localhost:8080/api/test/getList'
            ,cols: [[
                {type:'checkbox'}
                ,{field:'id',  title: 'ID', sort: true}
                ,{field:'empNo',title: '員工編號'}
                ,{field:'empName',title: '員工名稱'}
                ,{field:'salary', title: '薪資'}
                ,{field:'job', title: '職稱'} //minWidth：區域性定義當前單元格的最小寬度，layui 2.2.1 新增
                ,{field:'entryTime', title: '入職時間'}
            ]]
        });

        //指定允許上傳的檔案型別
        upload.render({
            elem: '#test3'
            ,url: 'http://localhost:8080/api/test/readExcel' //改成您自己的上傳介面
            ,accept: 'file' //普通檔案
            ,done: function(res){
                layer.msg('上傳成功');
                console.log(res);
            }
        });

        //Excel後臺匯出
        $("#test4").click(function () {
            // 檔名稱可以根據自己需要進行設定
            window.open('http://localhost:8080/api/test/exportExcel?fileName=員工表匯出測試.xlsx')
        })

        //Excel通過layui匯出
        $("#test5").click(function () {
            // console.log("123")
            var checkStatus = table.checkStatus('test'); //test 即為table繫結的id
            //獲取選中行的資料
            var data = checkStatus.data;

            //將上述表格示例中的指定資料匯出為 Excel 檔案
            table.exportFile(ins1.config.id, data); //data 為該例項中的任意數量的資料
        })

    });
</script>
</body>
</html>

  由於部落格園還不支援上傳視訊，我就放幾張執行的效果圖吧，本文程式碼也已經上傳至gitHub，本文有些程式碼沒有寫出來，可以到gitHub上把程式碼拉下來進行測試：


  因為本文只是對excel的匯入和匯出進行測試，並沒有來連線資料進行入庫操作，但在匯入Excel這個介面中，我已經獲取到了匯入的資料，並在控制檯列印了出來，如下：