java利用poi、Graphics2D技术，读取excel表格绘制成图片

首先感谢，丁丁-全栈工程师的博客https://www.cnblogs.com/newflydd/p/4912662.html

刚刚换工作，老大布置新任务，读取excel表格，按照表格样式生成图片。以前做过读取数据库生成excel，读取excel插入数据库，图片类的操作第一次接触，瞬间懵逼了。前辈说的好——有问题找百度，现在我们遇到的问题，基本上别人都遇到过，网上啥都有。结果还真没有，有的话也是方法过时、jar包更新不能用，纠结半天，完成任务。

原型图：

效果图：

废话不多说上代码。

1.先上需要的jar包

		
			org.apache.poi
			poi
			3.16
		
		
			org.apache.poi
			poi-ooxml
			3.15
		

用的maven，不懂的看后续博客，也可以自己百度学习。这两个是核心jar包，其他通用jar包自己添加。

2.核心代码

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;

import javax.imageio.ImageIO;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
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.CellType;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelTest {

	public static void test(String path) throws Exception {
		int sheetNum = 1;//读取表格第几页
		int imageWidth = 0;//图片宽度
		int imageHeight = 0;//图片高度

		// int nullRowCount = 0;

		InputStream inputStream = new FileInputStream(path);
		XSSFWorkbook workbook = new XSSFWorkbook(inputStream);
		XSSFSheet sheet = workbook.getSheetAt(sheetNum);
		List> excelList = readXlsx(path, sheetNum);
		List rangeAddress = sheet.getMergedRegions(); // 获取整个sheet中合并单元格组合的集合
		//根据读取数据，动态获得表边界行列
		int totalRow = excelList.size() + 1;
		int totalCol = excelList.get(0).size();
		
		//创建单元格数组，用于遍历单元格
		UserCell[][] cells = new UserCell[totalRow + 1][totalCol + 1];
		int[] rowPixPos = new int[totalRow + 1];// 存放行边界
		rowPixPos[0] = 0;
		int[] colPixPos = new int[totalCol + 1];// 存放列边界
		colPixPos[0] = 0;
		//开始遍历单元格
		for (int i = 0; i < totalRow; i++) {
			for (int j = 1; j < totalCol; j++) {
				cells[i][j] = new UserCell();
				cells[i][j].setCell(sheet.getRow(i).getCell(j));
				cells[i][j].setRow(i);
				cells[i][j].setCol(j);
				boolean ifShow = !(sheet.isColumnHidden(j) || sheet.getRow(i).getZeroHeight());
				cells[i][j].setShow(ifShow);
				// 计算所求区域宽度
				float widthPix = !ifShow ? 0 : (sheet.getColumnWidthInPixels(j)); // 如果该单元格是隐藏的，则置宽度为0
				if (i == 0) {
					imageWidth += widthPix;
				}
				colPixPos[j + 1] = (int) (widthPix * 1.15 + colPixPos[j]);
			}
			// 计算所求区域高度
			boolean ifShow = (i >= 0); // 行序列在指定区域中间
			ifShow = ifShow && !sheet.getRow(i).getZeroHeight(); // 行序列不能隐藏
			float heightPoint = !ifShow ? 0 : (sheet.getRow(i).getHeightInPoints()); // 如果该单元格是隐藏的，则置高度为0
			imageHeight += heightPoint;
			rowPixPos[i + 1] = (int) (heightPoint * 96 / 72) + rowPixPos[i];
		}
		imageHeight = imageHeight * 96 / 72;
		imageWidth = imageWidth * 115 / 100;

		/* ------------------------------ */
		List grids = new ArrayList();
		for (int i = 0; i < totalRow; i++) {
			for (int j = 1; j < totalCol; j++) {
				Grid grid = new Grid();
				// 设置坐标和宽高
				grid.setX(colPixPos[j]);
				grid.setY(rowPixPos[i]);
				grid.setWidth(colPixPos[j + 1] - colPixPos[j]);
				grid.setHeight(rowPixPos[i + 1] - rowPixPos[i]);
				grid.setRow(cells[i][j].getRow());
				grid.setCol(cells[i][j].getCol());
				grid.setShow(cells[i][j].isShow());

				// 判断是否为合并单元格
				int[] isInMergedStatus = isInMerged(grid.getRow(), grid.getCol(), rangeAddress);
				if (isInMergedStatus[0] == 0 && isInMergedStatus[1] == 0) {
					// 此单元格是合并单元格，并且不是第一个单元格，需要跳过本次循环，不进行绘制
					continue;
				} else if (isInMergedStatus[0] != -1 && isInMergedStatus[1] != -1) {
					// 此单元格是合并单元格，并且属于第一个单元格，则需要调整网格大小
					int lastRowPos = isInMergedStatus[0] > totalRow - 1 ? totalRow - 1 : isInMergedStatus[0];
					int lastColPos = isInMergedStatus[1] > totalCol - 1 ? totalCol - 1 : isInMergedStatus[1];
					grid.setWidth(colPixPos[lastColPos + 1] - colPixPos[j]);
					grid.setHeight(rowPixPos[lastRowPos + 1] - rowPixPos[i]);

				}
				// 单元格背景颜色
				Cell cell = cells[i][j].getCell();
				if (cell != null) {
					CellStyle cs = cell.getCellStyle();
					grid.setBgColor(cs.getFillForegroundColorColor());
					// 设置字体
					org.apache.poi.ss.usermodel.Font font = workbook.getFontAt(cs.getFontIndex());
					grid.setFont(font);
					// 设置前景色
					grid.setFtColor(cs.getFillBackgroundColorColor());
					// 设置文本
					String strCell;
					CellType cellType = cell.getCellTypeEnum();
					switch (cellType) {
					case STRING:
						strCell = cell.getStringCellValue();
						break;
					case NUMERIC:
						strCell = String.valueOf(cell.getNumericCellValue());
						break;
					case BLANK:
						strCell = "";
						break;
					case FORMULA:
						try {
							strCell = String.valueOf(cell.getNumericCellValue());
						} catch (IllegalStateException e) {
							strCell = String.valueOf(cell.getRichStringCellValue());
						}
						break;
					default:
						strCell = "";
						break;
					}
					if (cell.getCellStyle().getDataFormatString().contains("0.00%")) {
						try {
							double dbCell = Double.valueOf(strCell);
							strCell = new DecimalFormat("0.00").format(dbCell * 100) + "%";
						} catch (NumberFormatException e) {
						}
					}
					grid.setText(strCell.matches("\\w*\\.0") ? strCell.substring(0, strCell.length() - 2) : strCell);
				}
				grids.add(grid);
			}
		}

		BufferedImage image = new BufferedImage(imageWidth, imageHeight, BufferedImage.TYPE_INT_RGB);

		Graphics2D g2d = image.createGraphics();

		g2d.setColor(Color.white);
		g2d.fillRect(0, 0, imageWidth, imageHeight);
		// 平滑字体
		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
		g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_NORMALIZE);
		g2d.setRenderingHint(RenderingHints.KEY_TEXT_LCD_CONTRAST, 140);
		g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
		g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
		// 绘制表格
		for (Grid g : grids) {
			if (!g.isShow()) {
				continue;
			}
			// 绘制背景色
			g2d.setColor(g.getBgColor() == null ? Color.white : g.getBgColor());
			g2d.fillRect(g.getX(), g.getY(), g.getWidth(), g.getHeight());

			// 绘制边框
			g2d.setColor(Color.black);
			g2d.setStroke(new BasicStroke(1));
			g2d.drawRect(g.getX(), g.getY(), g.getWidth(), g.getHeight());

			// 绘制文字,居中显示
			g2d.setColor(g.getFtColor());
			Font font = g.getFont();
			if (font == null) {
				continue;
			}
			FontMetrics fm = g2d.getFontMetrics(font);
			int strWidth = fm.stringWidth(g.getText());// 获取将要绘制的文字宽度
			g2d.setFont(font);
			g2d.drawString(g.getText(), g.getX() + (g.getWidth() - strWidth) / 2,
					g.getY() + (g.getHeight() - font.getSize()) / 2 + font.getSize());
		}
		//表格最后一行有可能不显示，手动画上一行
		g2d.drawLine(0, imageHeight - 1, imageWidth - 4, imageHeight - 1);
		
		g2d.dispose();
		ImageIO.write(image, "png", new File("d:/test.png"));

		System.out.println("Output to PNG file Success!");
	}

	/**
	 * 判断Excel中的单元格是否为合并单元格
	 *
	 * @param row
	 * @param col
	 * @param rangeAddress
	 * @return 如果不是合并单元格返回{-1,-1},如果是合并单元格并且是一个单元格返回{lastRow,lastCol},
	 *         如果是合并单元格并且不是第一个格子返回{0,0}
	 */
	private static int[] isInMerged(int row, int col, List rangeAddress) {
		int[] isInMergedStatus = { -1, -1 };
		for (CellRangeAddress cra : rangeAddress) {
			if (row == cra.getFirstRow() && col == cra.getFirstColumn()) {
				isInMergedStatus[0] = cra.getLastRow();
				isInMergedStatus[1] = cra.getLastColumn();
				return isInMergedStatus;
			}
			if (row >= cra.getFirstRow() && row <= cra.getLastRow()) {
				if (col >= cra.getFirstColumn() && col <= cra.getLastColumn()) {
					isInMergedStatus[0] = 0;
					isInMergedStatus[1] = 0;
					return isInMergedStatus;
				}
			}
		}
		return isInMergedStatus;
	}

	public static List> readXlsx(String path, int pageNum) throws Exception {
		InputStream in = new FileInputStream(path);
		XSSFWorkbook xssfWorkbook = new XSSFWorkbook(in);
		List> resultList = new ArrayList>();
		// 遍历每一页，并循环处理当前页
		// for (int numSheet = 0; numSheet < xssfWorkbook.getNumberOfSheets();
		// numSheet++) {
		XSSFSheet xssfSheet = xssfWorkbook.getSheetAt(pageNum);// 获取当前页
		if (xssfSheet == null) {
			// continue;
		} else {
			// 处理当前页，并处理每一行
			for (int rowNum = 0; rowNum < xssfSheet.getLastRowNum(); rowNum++) {
				XSSFRow xssfRow = xssfSheet.getRow(rowNum);// 获取行数据

				int minColIX = xssfRow.getFirstCellNum();// 第一行数据
				int maxColIX = xssfRow.getLastCellNum();// 总行数
				List rowList = new ArrayList();
				// 遍历该行，处理该行数据
				for (int colIX = minColIX; colIX < maxColIX; colIX++) {
					XSSFCell cell = xssfRow.getCell(colIX);// 获取单元格
					if (cell == null) {
						continue;
					} else {
						rowList.add(cell.toString());
					}
				}
				resultList.add(rowList);
			}
		}
		// }
		return resultList;
	}

	/**
	 * 读取xls文件
	 * 
	 * @param path
	 * @return
	 * @throws Exception
	 */
	public static List> readXls(String path, int num) throws Exception {
		InputStream in = new FileInputStream(path);
		HSSFWorkbook hssfWorkbook = new HSSFWorkbook(in);
		List> resultList = new ArrayList>();
		// 遍历每一页，并循环处理当前页
		// for (int numSheet = 0; numSheet < hssfWorkbook.getNumberOfSheets();
		// numSheet++) {
		HSSFSheet hssfSheet = hssfWorkbook.getSheetAt(num);// 获取当前页
		if (hssfSheet == null) {
			// continue;
		} else {
			// 处理当前页，并处理每一行
			for (int rowNum = 0; rowNum < hssfSheet.getLastRowNum(); rowNum++) {
				HSSFRow hssfRow = hssfSheet.getRow(rowNum);// 获取行数据

				int minColIX = hssfRow.getFirstCellNum();// 第一行数据
				int maxColIX = hssfRow.getLastCellNum();// 总行数
				List rowList = new ArrayList();
				// 遍历该行，处理该行数据
				for (int colIX = minColIX; colIX < maxColIX; colIX++) {
					HSSFCell cell = hssfRow.getCell(colIX);// 获取单元格
					if (cell == null) {
						continue;
					} else {
						rowList.add(cell.toString());
					}
				}
				resultList.add(rowList);
			}
		}
		// }
		return resultList;
	}

	public static void main(String[] args) throws Exception {
		String path = "E:/excel/test.xlsx";
		test(path);
	}

}

3.上面是核心代码，再添上两个实体类

     UserCell类，用于单元格处理

import java.awt.Color;

import org.apache.poi.ss.usermodel.Cell;

public class UserCell  {
    private Cell cell;
    private int row;
    private int col;
    private boolean show;
    private String text="";
    private Color   color=null;
      
    public Cell getCell() {
        return cell;
    }
    public void setCell(Cell cell) {
        this.cell = cell;
    }
    public int getRow() {
        return row;
    }
    public void setRow(int row) {
        this.row = row;
    }
    public int getCol() {
        return col;
    }
    public void setCol(int col) {
        this.col = col;
    }
    public boolean isShow() {
        return show;
    }
    public void setShow(boolean show) {
        this.show = show;
    }
    public String getText() {
        return text;
    }
    public void setText(String text) {
        this.text = text;
    }
      
    public Color getColor() {
        return color;
    }
    public void setColor(Color color) {
        this.color = color;
    }
}

    Grid类，用于表格绘制

import java.awt.Color;
import java.awt.Font;

import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.xssf.usermodel.XSSFColor;

public class Grid {
	private boolean show;
	private int row; // 对应Excel中的row,也可以理解为cells[i][j]的i
	private int col; // 对应Excel中的col,也可以理解为cells[i][j]的j
	private int x; // x坐标
	private int y; // y坐标
	private int width;
	private int height;
	private String text;
	private Font font; 
	//= new Font("微软雅黑", Font.PLAIN, 12);
	private Color bgColor = null;
	private Color ftColor = null;

	public int getRow() {
		return row;
	}

	public void setRow(int row) {
		this.row = row;
	}

	public int getCol() {
		return col;
	}

	public void setCol(int col) {
		this.col = col;
	}

	public int getX() {
		return x;
	}

	public void setX(int x) {
		this.x = x;
	}

	public int getY() {
		return y;
	}

	public void setY(int y) {
		this.y = y;
	}

	public boolean isShow() {
		return show;
	}

	public void setShow(boolean show) {
		this.show = show;
	}

	public int getWidth() {
		return width;
	}

	public void setWidth(int width) {
		this.width = width;
	}

	public int getHeight() {
		return height;
	}

	public void setHeight(int height) {
		this.height = height;
	}

	public String getText() {
		return text;
	}

	public void setText(String text) {
		this.text = text;
	}

	public Color getBgColor() {
		return bgColor;
	}

	/**
	 * 将poi.ss.usermodel.Color 转换成 java.awt.Color
	 * @param
	 * color
	 */
	public void setBgColor(org.apache.poi.ss.usermodel.Color color) {
		this.bgColor = poiColor2awtColor(color);
	}

	public void setBgColor(java.awt.Color color) {
		this.bgColor = color;
	}

	public Color getFtColor() {
		return ftColor;
	}

	public void setFtColor(org.apache.poi.ss.usermodel.Color color) {
		this.ftColor = poiColor2awtColor(color);
	}

	public Font getFont() {
		return font;
	}

	public void setFont(org.apache.poi.ss.usermodel.Font font) {
		if (font != null) {
			this.font = new java.awt.Font(font.getFontName(), Font.BOLD, font.getFontHeight() / 20 + 2);
		}
	}

	private java.awt.Color poiColor2awtColor(org.apache.poi.ss.usermodel.Color color) {
		Color awtColor = null;
		if (color instanceof XSSFColor) { // .xlsx
			XSSFColor xc = (XSSFColor) color;
			String rgbHex = xc.getARGBHex();
			if (rgbHex != null) {
				awtColor = new Color(Integer.parseInt(rgbHex.substring(2), 16));
			}
		} else if (color instanceof HSSFColor) { // .xls
			HSSFColor hc = (HSSFColor) color;
			short[] s = hc.getTriplet();
			if (s != null) {
				awtColor = new Color(s[0], s[1], s[2]);
			}
		}
		return awtColor;
	}
}

基本上复制过去，引入jar包就能使用，代码不太完善，大佬多多提意见。