excel导出

pom:引入easyexcel包

<!-- easyexcel 导入导出 -->
<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>easyexcel</artifactId>
  <version>2.2.7</version>
</dependency>

测试代码：

    public static void main(String[] args) {
        String fileName = "D:\\excel"+ System.currentTimeMillis() + ".xlsx";
        // 头的策略
        WriteCellStyle headWriteCellStyle = new WriteCellStyle();
        // 内容的策略
        WriteCellStyle contentWriteCellStyle = new WriteCellStyle();
        //自动换行的代码
        contentWriteCellStyle.setWrapped(true);
        // 这个策略是 头是头的样式 内容是内容的样式 其他的策略可以自己实现
        HorizontalCellStyleStrategy horizontalCellStyleStrategy =
                new HorizontalCellStyleStrategy(headWriteCellStyle, contentWriteCellStyle);
        EasyExcel.write(fileName)
                .registerWriteHandler(new CustomCellWriteHeightConfig())//添加excel单元格高度的计算策略，不需要改动
                .registerWriteHandler(new CustomCellWriteWeightConfig())//添加excel单元格长度的计算策略，不需要改动
                .registerWriteHandler(horizontalCellStyleStrategy)//换行
                // 这里放入动态头
                .head(head()).sheet("模板")
                // 当然这里数据也可以用 List<List<String>> 去传入
                .doWrite(data());
    }
    private static List<List<String>> head() {
        List<List<String>> list = new ArrayList<>();
        List<String> head0 = new ArrayList<>();
        head0.add("string" );
        List<String> head1 = new ArrayList<>();
        head1.add("number");
        List<String> head2 = new ArrayList<>();
        head2.add("date");
        list.add(head0);
        list.add(head1);
        list.add(head2);
        return list;
    }
    private static List<List<String>> data() {
        List<List<String>> list = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            List<String> stringList = new ArrayList<>();
            stringList.add("coum1");
            stringList.add("coum2");
            stringList.add("coum3");
            list.add(stringList);
        }
        return list;
    }

单元格高度和宽度的定义类：

package excelUtil;
import com.alibaba.excel.write.style.row.AbstractRowHeightStyleStrategy;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import java.util.Iterator;
//自适应行宽
public class CustomCellWriteHeightConfig extends AbstractRowHeightStyleStrategy {
    /**
     * 默认高度
     */
    private static final Integer DEFAULT_HEIGHT = 300;
    @Override
    protected void setHeadColumnHeight(Row row, int relativeRowIndex) {
    }
    @Override
    protected void setContentColumnHeight(Row row, int relativeRowIndex) {
        Iterator<Cell> cellIterator = row.cellIterator();
        if (!cellIterator.hasNext()) {
            return;
        }
        // 默认为 1行高度
        Integer maxHeight = 1;
        while (cellIterator.hasNext()) {
            Cell cell = cellIterator.next();
            switch (cell.getCellTypeEnum()) {
                case STRING:
                    if (cell.getStringCellValue().indexOf("\n") != -1) {
                        int length = cell.getStringCellValue().split("\n").length;
                        maxHeight = Math.max(maxHeight, length);
                    }
                    break;
                default:
                    break;
            }
        }
        row.setHeight((short) (maxHeight * DEFAULT_HEIGHT));
    }
}

//自定义行高

package excelUtil;
import com.alibaba.excel.metadata.CellData;
import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.util.CollectionUtils;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.style.column.AbstractColumnWidthStyleStrategy;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Sheet;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class CustomCellWriteWeightConfig extends AbstractColumnWidthStyleStrategy {
    private Map<Integer, Map<Integer, Integer>> CACHE = new HashMap<>();
    @Override
    protected void setColumnWidth(WriteSheetHolder writeSheetHolder, List<CellData> cellDataList, Cell cell, Head head, Integer integer, Boolean isHead) {
        boolean needSetWidth = isHead || !CollectionUtils.isEmpty(cellDataList);
        if (needSetWidth) {
            Map<Integer, Integer> maxColumnWidthMap = CACHE.get(writeSheetHolder.getSheetNo());
            if (maxColumnWidthMap == null) {
                maxColumnWidthMap = new HashMap<>();
                CACHE.put(writeSheetHolder.getSheetNo(), maxColumnWidthMap);
            }
            Integer columnWidth = this.dataLength(cellDataList, cell, isHead);
            if (columnWidth >= 0) {
                if (columnWidth > 254) {
                    columnWidth = 254;
                }
                Integer maxColumnWidth = maxColumnWidthMap.get(cell.getColumnIndex());
                if (maxColumnWidth == null || columnWidth > maxColumnWidth) {
                    maxColumnWidthMap.put(cell.getColumnIndex(), columnWidth);
                    Sheet sheet = writeSheetHolder.getSheet();
                    sheet.setColumnWidth(cell.getColumnIndex(), columnWidth * 256);
                }
            }
        }
    }
    /**
     * 计算长度
     *
     * @param cellDataList
     * @param cell
     * @param isHead
     * @return
     */
    private Integer dataLength(List<CellData> cellDataList, Cell cell, Boolean isHead) {
        if (isHead) {
            return cell.getStringCellValue().getBytes().length;
        } else {
            //此处固定写成27，页面样式好看一点，否则直接计算，会自动一整行显示，不会换行--shenshuai
            return 27;
        }
    }
}

最后导出效果：