代码说明用eclipse获取excel表格中停车位，以平面图形式展现在页面，同时接收数据填充停车位颜色

以下是代码说明：

1. 首先，需要在 Eclipse 中创建一个 Web 项目，并引入 Apache POI 和 JFreeChart 库。Apache POI 库用于读取 Excel 表格，JFreeChart 库用于绘制平面图形。

2. 在项目中创建一个名为 "upload" 的文件夹，用于存放上传的 Excel 表格。

3. 在项目中创建一个名为 "images" 的文件夹，用于存放生成的停车位平面图。

4. 创建一个名为 "UploadServlet" 的 Servlet，用于处理上传的 Excel 表格。在 doPost() 方法中，使用 Apache POI 库读取 Excel 表格中的数据，并将数据存储在一个 List 中。然后调用 generateParkingLot() 方法生成停车位平面图，并将平面图保存到 "images" 文件夹中。

5. 创建一个名为 "ParkingLotServlet" 的 Servlet，用于展示停车位平面图。在 doGet() 方法中，使用 JFreeChart 库绘制停车位平面图，并将其展示在页面上。同时，根据之前存储的数据，填充停车位的颜色。

6. 在页面上添加一个表单，用于上传 Excel 表格。

7. 在页面上添加一个 Canvas 元素，用于展示停车位平面图。

8. 使用 JavaScript 实现上传表格和展示平面图的交互。在表单提交时，将表格上传到 "upload" 文件夹中，并通过 Ajax 调用 ParkingLotServlet 获取停车位平面图。在获取到平面图后，将其绘制到 Canvas 元素中。

代码示例：（仅供参考）

UploadServlet.java

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.poi.ss.usermodel.Cell;
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.ss.usermodel.WorkbookFactory;

@WebServlet("/upload")
public class UploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String fileName = request.getParameter("file");
        String filePath = getServletContext().getRealPath("") + File.separator + "upload" + File.separator + fileName;
        File file = new File(filePath);
        FileInputStream inputStream = new FileInputStream(file);
        Workbook workbook = WorkbookFactory.create(inputStream);
        Sheet sheet = workbook.getSheetAt(0);
        List<String[]> data = new ArrayList<>();
        for (Row row : sheet) {
            String[] rowData = new String[row.getLastCellNum()];
            for (int i = 0; i < row.getLastCellNum(); i++) {
                Cell cell = row.getCell(i);
                if (cell != null) {
                    switch (cell.getCellType()) {
                    case STRING:
                        rowData[i] = cell.getStringCellValue();
                        break;
                    case NUMERIC:
                        rowData[i] = String.valueOf(cell.getNumericCellValue());
                        break;
                    case BOOLEAN:
                        rowData[i] = String.valueOf(cell.getBooleanCellValue());
                        break;
                    default:
                        rowData[i] = "";
                    }
                } else {
                    rowData[i] = "";
                }
            }
            data.add(rowData);
        }
        inputStream.close();
        ParkingLotGenerator.generateParkingLot(data);
        response.sendRedirect("ParkingLotServlet");
    }
}

ParkingLotGenerator.java

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.List;
import javax.imageio.ImageIO;

public class ParkingLotGenerator {
    private static final int WIDTH = 800;
    private static final int HEIGHT = 600;
    private static final int BORDER = 50;
    private static final int ROWS = 6;
    private static final int COLUMNS = 8;

    public static void generateParkingLot(List<String[]> data) throws IOException {
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_ARGB);
        Graphics2D graphics = image.createGraphics();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0, 0, WIDTH, HEIGHT);
        graphics.setColor(Color.BLACK);
        graphics.drawRect(BORDER, BORDER, WIDTH - BORDER * 2, HEIGHT - BORDER * 2);
        for (int i = 1; i < ROWS; i++) {
            int y = BORDER + (HEIGHT - BORDER * 2) / ROWS * i;
            graphics.drawLine(BORDER, y, WIDTH - BORDER, y);
        }
        for (int i = 1; i < COLUMNS; i++) {
            int x = BORDER + (WIDTH - BORDER * 2) / COLUMNS * i;
            graphics.drawLine(x, BORDER, x, HEIGHT - BORDER);
        }
        for (int i = 0; i < data.size(); i++) {
            int row = Integer.parseInt(data.get(i)[0]);
            int column = Integer.parseInt(data.get(i)[1]);
            String status = data.get(i)[2];
            int x = BORDER + (WIDTH - BORDER * 2) / COLUMNS * column + (WIDTH - BORDER * 2) / COLUMNS / 4;
            int y = BORDER + (HEIGHT - BORDER * 2) / ROWS * row + (HEIGHT - BORDER * 2) / ROWS / 4;
            int w = (WIDTH - BORDER * 2) / COLUMNS / 2;
            int h = (HEIGHT - BORDER * 2) / ROWS / 2;
            if (status.equals("空闲")) {
                graphics.setColor(Color.GREEN);
            } else if (status.equals("已预约")) {
                graphics.setColor(Color.YELLOW);
            } else if (status.equals("已占用")) {
                graphics.setColor(Color.RED);
            } else {
                graphics.setColor(Color.GRAY);
            }
            graphics.fillRect(x, y, w, h);
        }
        ImageIO.write(image, "png", new File(getServletContext().getRealPath("") + File.separator + "images" + File.separator + "parking_lot.png"));
    }
}

ParkingLotServlet.java

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.data.category.DefaultCategoryDataset;

@WebServlet("/ParkingLotServlet")
public class ParkingLotServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        BufferedImage image = ImageIO.read(new File(getServletContext().getRealPath("") + File.separator + "images" + File.separator + "parking_lot.png"));
        response.setContentType("image/png");
        ImageIO.write(image, "png", response.getOutputStream());
    }
}

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Parking Lot</title>
<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script>
$(document).ready(function() {
    $("#uploadForm").submit(function(event) {
        event.preventDefault();
        var file = $("#file").prop("files")[0];
        var formData = new FormData();
        formData.append("file", file);
        $.ajax({
            url: "upload",
            type: "POST",
            data: formData,
            processData: false,
            contentType: false,
            success: function() {
                var canvas = document.getElementById("canvas");
                var context = canvas.getContext("2d");
                var image = new Image();
                image.onload = function() {
                    context.drawImage(image, 0, 0);
                };
                image.src = "ParkingLotServlet";
            },
            error: function() {
                alert("上传失败");
            }
        });
    });
});
</script>
</head>
<body>
    <form id="uploadForm">
        <input type="file" id="file" name="file" accept=".xlsx">
        <button type="submit">上传</button>
    </form>
    <canvas id="canvas" width="800" height="600"></canvas>
</body>
</html>

在执行代码之前，需要确保已正确引入 Apache POI 和 JFreeChart 库。另外，需要将代码中的路径根据实际情况进行修改。