【POI】 工具类导出导入 三

工具类准备

1.自定义注解

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface ExcelAttribute {
    /** 对应的列名称 */
    String name() default "";

    /** 列序号 */
    int sort();

    /** 字段类型对应的格式 */
    String format() default "";
}

2.导出工具类

package com.bgzx.poi.utils;

import lombok.Getter;
import lombok.Setter;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.net.URLEncoder;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@Getter
@Setter
@SuppressWarnings("all")
public class ExcelExportUtil<T> {

    private int rowIndex;
    private int styleIndex;
    private String templatePath;
    private Class clazz;
    private  Field fields[];

    public ExcelExportUtil(Class clazz,int rowIndex,int styleIndex) {
        this.clazz = clazz;
        this.rowIndex = rowIndex;
        this.styleIndex = styleIndex;
        fields = clazz.getDeclaredFields();
    }

    /**
     * 基于注解导出
     */
    public void export(HttpServletResponse response,InputStream is, List<T> objs,String fileName) throws Exception {

        XSSFWorkbook workbook = new XSSFWorkbook(is);
        Sheet sheet = workbook.getSheetAt(0);

        CellStyle[] styles = getTemplateStyles(sheet.getRow(styleIndex));

        AtomicInteger datasAi = new AtomicInteger(rowIndex);
        for (T t : objs) {
            Row row = sheet.createRow(datasAi.getAndIncrement());
            for(int i=0;i<styles.length;i++) {
                Cell cell = row.createCell(i);
                cell.setCellStyle(styles[i]);
                for (Field field : fields) {
                    if(field.isAnnotationPresent(ExcelAttribute.class)){
                        field.setAccessible(true);
                        ExcelAttribute ea = field.getAnnotation(ExcelAttribute.class);
                        if(i == ea.sort()) {
                            cell.setCellValue(field.get(t).toString());
                        }
                    }
                }
            }
        }
        fileName = URLEncoder.encode(fileName, "UTF-8");
        response.setContentType("application/octet-stream");
        response.setHeader("content-disposition", "attachment;filename=" + new String(fileName.getBytes("ISO8859-1")));
        response.setHeader("filename", fileName);
        workbook.write(response.getOutputStream());
    }



    public CellStyle[] getTemplateStyles(Row row) {
        CellStyle [] styles = new CellStyle[row.getLastCellNum()];
        for(int i=0;i<row.getLastCellNum();i++) {
            styles[i] = row.getCell(i).getCellStyle();
        }
        return styles;
    }
}

3.导入工具类

package com.bgzx.poi.utils;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.DateUtil;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.InputStream;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class ExcelImportUtil<T> {

    private Class clazz;
    private  Field fields[];

    public ExcelImportUtil(Class clazz) {
        this.clazz = clazz;
        fields = clazz.getDeclaredFields();
    }


    /**
     * 基于注解读取excel
     */
    public List<T> readExcel(InputStream is, int rowIndex,int cellIndex) {
        List<T> list = new ArrayList<T>();
        T entity = null;
        try {
            XSSFWorkbook workbook = new XSSFWorkbook(is);
            Sheet sheet = workbook.getSheetAt(0);

            for (int rowNum = rowIndex; rowNum <= sheet.getLastRowNum(); rowNum++) {
                Row row = sheet.getRow(rowNum);
                entity = (T) clazz.newInstance();

                for (int j = cellIndex; j < row.getLastCellNum(); j++) {
                    Cell cell = row.getCell(j);
                    for (Field field : fields) {
                        if(field.isAnnotationPresent(ExcelAttribute.class)){
                            field.setAccessible(true);
                            ExcelAttribute ea = field.getAnnotation(ExcelAttribute.class);
                            if(j == ea.sort()) {
                                field.set(entity, covertAttrType(field, cell));
                            }
                        }
                    }
                }
                list.add(entity);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return list;
    }


    /**
     * 类型转换 将cell 单元格格式转为 字段类型
     */
    private Object covertAttrType(Field field, Cell cell) throws Exception {
        String fieldType = field.getType().getSimpleName();
        if ("String".equals(fieldType)) {
            return getValue(cell);
        }else if ("Date".equals(fieldType)) {
            return new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").parse(getValue(cell)) ;
        }else if ("int".equals(fieldType) || "Integer".equals(fieldType)) {
            return Integer.parseInt(getValue(cell));
        }else if ("double".equals(fieldType) || "Double".equals(fieldType)) {
            return Double.parseDouble(getValue(cell));
        }else {
            return null;
        }
    }


    /**
     * 格式转为String
     * @param cell
     * @return
     */
    public String getValue(Cell cell) {
        if (cell == null) {
            return "";
        }
        switch (cell.getCellType()) {
            case STRING:
                return cell.getRichStringCellValue().getString().trim();
            case NUMERIC:
                if (DateUtil.isCellDateFormatted(cell)) {
                    Date dt = DateUtil.getJavaDate(cell.getNumericCellValue());
                    return new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(dt);
                } else {
                    // 防止数值变成科学计数法
                    String strCell = "";
                    Double num = cell.getNumericCellValue();
                    BigDecimal bd = new BigDecimal(num.toString());
                    if (bd != null) {
                        strCell = bd.toPlainString();
                    }
                    // 去除 浮点型 自动加的 .0
                    if (strCell.endsWith(".0")) {
                        strCell = strCell.substring(0, strCell.indexOf("."));
                    }
                    return strCell;
                }
            case BOOLEAN:
                return String.valueOf(cell.getBooleanCellValue());
            default:
                return "";
        }
    }
}

5.实体类

@Data
@ToString
public class User {

  @ExcelAttribute(sort = 0)
  private String id;
  @ExcelAttribute(sort = 1)
  private String name;
  @ExcelAttribute(sort = 2)
  private Double age;
  @ExcelAttribute(sort = 3)
  private String address;
  @ExcelAttribute(sort = 4)
  private Date time;
}

6.导出模板

7.导入示例

@GetMapping("/utils/import")
public void utilsImport(HttpServletResponse response) throws Exception {
  ExcelImportUtil<User> excelImportUtil = new ExcelImportUtil<>(User.class);
  FileInputStream fileInputStream = new FileInputStream(new File("C:\\Users\\lenovo\\Desktop\\user.xlsx"));
  List<User> users = excelImportUtil.readExcel(fileInputStream, 1, 0);
  for (User user : users) {
    System.out.println(user);
  }
}

8.导出示例

@GetMapping("/utils/export")
public void utilsExport(HttpServletResponse response) throws Exception {
  List<User> users = new ArrayList<>();
  for(int i = 0 ; i < 100; i ++){
    User user = new User();
    user.setId(i + "");
    user.setName(i + "张三");
    user.setAddress("石家庄" + i);
    user.setAge((double)i);
    user.setTime(new Date());
    users.add(user);
  }

  Resource resource = new ClassPathResource("xslx/user.xlsx");
  @Cleanup FileInputStream fis = new FileInputStream(resource.getFile());
  ExcelExportUtil<User> excelExportUtil = new ExcelExportUtil<>(User.class,1,0);
  excelExportUtil.export(response,fis,users,"haha.xlsx");

}