Java导出Execl疑难点处理的实现

<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>poi-ooxml</artifactId>
			<version>3.8</version>
		</dependency>
		<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>poi-scratchpad</artifactId>
			<version>3.8</version>
		</dependency>

//创建第一行，索引是从0开始的
row = sheet.createRow(0);
//创建第一个单元格
XSSFCell cell0 = row.createCell(0);
//设置单元格文字
cell0.setCellValue("姓名");
//设置单元格样式
cell0.setCellStyle(cellStyleHead);
//跨单元格设置
//参数为 firstRow, lastRow, firstCol, lastCol
CellRangeAddress cellRange1 = new CellRangeAddress(0, 1, 0, 0);
sheet.addMergedRegion(cellRange1);
//注意如果直接在下面写设置边框的样式，可能会出现边框覆盖不全的情况，可能是样式覆盖问题
//所以应该在数据渲染完成之后，在代码的最后写跨单元格边框设置,这是非常重要的

//在数据渲染完成，调用封装的边框设置方法
setRegionStyle(wb, sheet, cellRange1);

 /**
   * 合并单元格之后设置边框
   *
   * @param wb   XSSFWorkbook对象
   * @param sheet sheet
   * @param region region
   */
  static void setRegionStyle(XSSFWorkbook wb, XSSFSheet sheet, CellRangeAddress region) {
    RegionUtil.setBorderTop(1, region, sheet, wb);
    RegionUtil.setBorderBottom(1, region, sheet, wb);
    RegionUtil.setBorderLeft(1, region, sheet, wb);
    RegionUtil.setBorderRight(1, region, sheet, wb);
  }

 //创建单元格样式
 XSSFCellStyle cellStyleContent = wb.createCellStyle();
//创建背景颜色 226, 239, 218 对应的就是RGB颜色 红绿蓝
 cellStyleContent.setFillForegroundColor(new XSSFColor(new java.awt.Color(226, 239, 218)));
//填充m
 cellStyleContent.setFillPattern(CellStyle.SOLID_FOREGROUND);

 XSSFRichTextString ts = new XSSFRichTextString("123456\r\n789");
 XSSFFont font2 = wb.createFont();
 //字体高度
font2.setFontHeightInPoints((short) 10);
// 字体
font2.setFontName("宋体");
//字体颜色
font2.setColor(HSSFColor.GREEN.index);
//那些字体要设置颜色，
//int startIndex 开始索引
//int endIndex 结束索引
// Font font 字体
ts.applyFont(5, ts.length(), font2);

//高度自适应
//XSSFRow row;
ExcelUtil.calcAndSetRowHeigt(row);

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.xssf.usermodel.*;

import java.util.HashMap;
import java.util.Map;

/**
 * @author Created by niugang on 2020/3/13/13:34
 */
public class ExcelUtil {


  private ExcelUtil() {
    throw new IllegalStateException("Utility class");
  }

  /**
   * 根据行内容重新计算行高
   *
   * @param sourceRow sourceRow
   */
  public static void calcAndSetRowHeigt(XSSFRow sourceRow) {
    for (int cellIndex = sourceRow.getFirstCellNum(); cellIndex <= sourceRow.getPhysicalNumberOfCells(); cellIndex++) {
      //行高
      double maxHeight = sourceRow.getHeight();
      XSSFCell sourceCell = sourceRow.getCell(cellIndex);
      //单元格的内容
      String cellContent = getCellContentAsString(sourceCell);
      if (null == cellContent || "".equals(cellContent)) {
        continue;
      }
      //单元格的宽高及单元格信息
      Map<String, Object> cellInfoMap = getCellInfo(sourceCell);
      Integer cellWidth = (Integer) cellInfoMap.get("width");
      Integer cellHeight = (Integer) cellInfoMap.get("height");
      if (cellHeight > maxHeight) {
        maxHeight = cellHeight;
      }
      XSSFCellStyle cellStyle = sourceCell.getCellStyle();
      //sourceRow.getSheet().getWorkbook()
      XSSFFont font = cellStyle.getFont();
      //字体的高度
      short fontHeight = font.getFontHeight();

      //cell内容字符串总宽度
      double cellContentWidth = cellContent.getBytes().length * 2 * 256;

      //字符串需要的行数 不做四舍五入之类的操作
      double stringNeedsRows = cellContentWidth / cellWidth;
      //小于一行补足一行
      if (stringNeedsRows < 1.0) {
        stringNeedsRows = 1.0;
      }

      //需要的高度 			(Math.floor(stringNeedsRows) - 1) * 40 为两行之间空白高度
      double stringNeedsHeight = (double) fontHeight * stringNeedsRows;
      //需要重设行高
      if (stringNeedsHeight > maxHeight) {
        maxHeight = stringNeedsHeight;
        //超过原行高三倍 则为5倍 实际应用中可做参数配置
        if (maxHeight / cellHeight > 5) {
          maxHeight = 5 * cellHeight;
        }
        //最后取天花板防止高度不够
        maxHeight = Math.ceil(maxHeight);
        //重新设置行高 同时处理多行合并单元格的情况
        Boolean isPartOfRowsRegion = (Boolean) cellInfoMap.get("isPartOfRowsRegion");
        if (isPartOfRowsRegion.equals(Boolean.TRUE)) {
          Integer firstRow = (Integer) cellInfoMap.get("firstRow");
          Integer lastRow = (Integer) cellInfoMap.get("lastRow");
          //平均每行需要增加的行高
          double addHeight = (maxHeight - cellHeight) / (lastRow - firstRow + 1);
          for (int i = firstRow; i <= lastRow; i++) {
            double rowsRegionHeight = sourceRow.getSheet().getRow(i).getHeight() + addHeight;
            rowsRegionHeight=rowsRegionHeight+10;
            sourceRow.getSheet().getRow(i).setHeight((short) rowsRegionHeight);
          }
        } else {
          maxHeight=maxHeight+10;
          sourceRow.setHeight((short) maxHeight);
        }
      }

    }
  }

  /**
   * 解析一个单元格得到数据
   *
   * @param cell cell
   * @return String
   */
  private static String getCellContentAsString(XSSFCell cell) {
    final String strZero =".0";
    if (null == cell) {
      return "";
    }
    String result = "";
    switch (cell.getCellType()) {
      case Cell.CELL_TYPE_NUMERIC:
        String s = String.valueOf(cell.getNumericCellValue());
        if (s != null) {
          if (s.endsWith(strZero)) {
            s = s.substring(0, s.length() - 2);
          }
        }
        result = s;
        break;
      case Cell.CELL_TYPE_STRING:
        result = String.valueOf(cell.getStringCellValue()).trim();
        break;
      case Cell.CELL_TYPE_BLANK:
        break;
      case Cell.CELL_TYPE_BOOLEAN:
        result = String.valueOf(cell.getBooleanCellValue());
        break;
      case Cell.CELL_TYPE_ERROR:
        break;
      default:
        break;
    }
    return result;
  }

  /**
   * 获取单元格及合并单元格的宽度
   *
   * @param cell cell
   * @return Map<String  ,    Object>
   */
  private static Map<String, Object> getCellInfo(XSSFCell cell) {
    XSSFSheet sheet = cell.getSheet();
    int rowIndex = cell.getRowIndex();
    int columnIndex = cell.getColumnIndex();

    boolean isPartOfRegion = false;
    int firstColumn = 0;
    int lastColumn = 0;
    int firstRow = 0;
    int lastRow = 0;
    int sheetMergeCount = sheet.getNumMergedRegions();
    for (int i = 0; i < sheetMergeCount; i++) {
      CellRangeAddress ca = sheet.getMergedRegion(i);
      firstColumn = ca.getFirstColumn();
      lastColumn = ca.getLastColumn();
      firstRow = ca.getFirstRow();
      lastRow = ca.getLastRow();
      if (rowIndex >= firstRow && rowIndex <= lastRow) {
        if (columnIndex >= firstColumn && columnIndex <= lastColumn) {
          isPartOfRegion = true;
          break;
        }
      }
    }
    Map<String, Object> map = new HashMap<>(16);
    int width = 0;
    int height = 0;
    boolean isPartOfRowsRegion = false;
    if (isPartOfRegion) {
      for (int i = firstColumn; i <= lastColumn; i++) {
        width += sheet.getColumnWidth(i);
      }
      for (int i = firstRow; i <= lastRow; i++) {
        height += sheet.getRow(i).getHeight();
      }
      if (lastRow > firstRow) {
        isPartOfRowsRegion = true;
      }
    } else {
      width = sheet.getColumnWidth(columnIndex);
      height += cell.getRow().getHeight();
    }
    map.put("isPartOfRowsRegion", isPartOfRowsRegion);
    map.put("firstRow", firstRow);
    map.put("lastRow", lastRow);
    map.put("width", width);
    map.put("height", height);
    return map;
  }
}