导出Excel是比较常用的功能，在此记录一下，省去了每次要去网上找代码的时间

1：首先看下数据库 order_info 只有简单的几个列

2：导入maven依赖

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.6</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.6</version>
        </dependency>

3：创建ExcelUtil工具类

import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;

public class ExcelUtil {

    /**
     * 导出Excel
     *
     * @param fileName  文件名
     * @param sheetName sheet名称
     * @param title     表头
     * @param data      二维数组格式的数据
     * @param response
     */
    public static void getHSSFwb(String fileName, String sheetName, String[] title, String data[][], HttpServletResponse response) {
        //创建文件、单个表格、行、单元格
        HSSFWorkbook wb = new HSSFWorkbook();
        HSSFSheet sheet = wb.createSheet(sheetName);
        HSSFRow row = sheet.createRow(0);
        HSSFCell cell = null;
        //标题Style
        HSSFCellStyle style = wb.createCellStyle();
        style.setFillForegroundColor(HSSFColor.GREY_50_PERCENT.index);
        style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
        style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
        style.setBorderRight(HSSFCellStyle.BORDER_THIN);
        style.setBorderTop(HSSFCellStyle.BORDER_THIN);
        style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        HSSFFont font = wb.createFont();  // 生成一个字体
        font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        font.setFontName("宋体");
        font.setColor(HSSFColor.WHITE.index);
        font.setFontHeightInPoints((short) 11);
        style.setFont(font);
        //内容Style
        HSSFCellStyle style2 = wb.createCellStyle();
        style2.setFillForegroundColor(HSSFColor.WHITE.index);
        style2.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        style2.setBorderBottom(HSSFCellStyle.BORDER_THIN);
        style2.setBorderLeft(HSSFCellStyle.BORDER_THIN);
        style2.setBorderRight(HSSFCellStyle.BORDER_THIN);
        style2.setBorderTop(HSSFCellStyle.BORDER_THIN);
        style2.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        style2.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
        HSSFFont font2 = wb.createFont();
        font2.setBoldweight(HSSFFont.BOLDWEIGHT_NORMAL);
        style2.setFont(font2);
         // 创建表头标题 第一行数据
        for (int i = 0; i < title.length; i++) {
            cell = row.createCell(i);
            cell.setCellValue(title[i]);
            cell.setCellStyle(style);
        }
        //填充数据 二维数组
        for (int i = 0; i < data.length; i++) {
            row = sheet.createRow(i + 1);
            for (int j = 0; j < data[i].length; j++) {
                cell = row.createCell(j);
                cell.setCellValue(data[i][j]);
                cell.setCellStyle(style2);
            }
        }
        //浏览器响应
        OutputStream output;
        try {
            output = response.getOutputStream();
            response.reset();
            //这里如果文件名想要为中文就要fileName=new String(fileName.getBytes(),"ISO8859-1")
            response.setHeader("Content-Disposition", "attachment;filename=" + new String(fileName.getBytes(), "ISO8859-1"));
            response.setContentType("application/vnd.ms-excel");
            wb.write(output);
            output.flush();
            output.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

4：这样就可以直接用了，看下Controller的代码吧

@RestController
public class ExcelController {

    @Autowired
    private OrderInfoService orderInfoService;

    @RequestMapping("excel")
    public void excel(HttpServletResponse response) {
        //select * from order_info
        List<OrderInfo> list = orderInfoService.getAllOrderInfo();
        String[] title = {"订单Id", "内容", "创建时间", "订单状态"};
        String fileName = "订单信息_" + new SimpleDateFormat("yyyy-MM-dd_HH_mm_ss").format(new Date()) + ".xls";
        String sheetName = "订单信息";
        //二维数组
        String[][] data = new String[list.size()][title.length];
        for (int i = 0; i < data.length; i++) {
            OrderInfo oi = list.get(i);
            data[i][0] = oi.getId().toString();
            data[i][1] = oi.getContent();
            data[i][2] = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(oi.getCreateTime());
            data[i][3] = oi.getStatus() == 1 ? "已完成" : "其它";  // Java 三元表达式
        }
        //工具类导出
        ExcelUtil.getHSSFwb(fileName, sheetName, title, data, response);
    }
}

5：浏览器输入你的controller访问路径，我这里的是 localhost:8080/excel，导出后效果：