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Java中Excel导出数据库

程序员文章站 2022-06-02 18:51:54
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//导出2003版本Excel文件。参数列表:Excel页签名,表头名,数据源集合,输出流包含文件地址,日期格式
    public void exportExcel(String title, String[] headers,Collection<T> dataset, OutputStream out, String pattern) {
    	// 声明一个工作薄
        HSSFWorkbook workbook = new HSSFWorkbook();
        // 生成一个表格
        HSSFSheet sheet = workbook.createSheet(title);
        // 设置表格默认列宽度为15个字节
        sheet.setDefaultColumnWidth((short) 15);
        // 生成一个样式
        HSSFCellStyle style = workbook.createCellStyle();
        // 生成一个字体
        HSSFFont font = workbook.createFont();
        font.setFontHeightInPoints((short) 12);
        // 把字体应用到当前的样式
        style.setFont(font);
        // 产生表格标题行
        HSSFRow row = sheet.createRow(0);
        for (short i = 0; i < headers.length; i++) {
            HSSFCell cell = row.createCell(i);
            cell.setCellStyle(style);
            HSSFRichTextString text = new HSSFRichTextString(headers[i]);
            cell.setCellValue(text);
        }
        // 遍历集合数据,产生数据行
        Iterator<T> it = dataset.iterator();
        int index = 0;
        while (it.hasNext()) {
            index++;
            row = sheet.createRow(index);
            T t = (T) it.next();
            // 利用反射,根据javabean属性的先后顺序,动态调用getXxx()方法得到属性值
            Field[] fields = t.getClass().getDeclaredFields();
            for (short i = 0; i < fields.length; i++) {
                HSSFCell cell = row.createCell(i);
                cell.setCellStyle(style);
                Field field = fields[i];
                String fieldName = field.getName();
                String getMethodName = "get"
                        + fieldName.substring(0, 1).toUpperCase()
                        + fieldName.substring(1);
                try {
                    Class tCls = t.getClass();
                    Method getMethod = tCls.getMethod(getMethodName,
                            new Class[] {});
                    Object value = getMethod.invoke(t, new Object[] {});
                    // 判断值的类型后进行强制类型转换
                    String textValue = null;
                     if (value instanceof Integer) {
                         int intValue = (Integer) value;
                         cell.setCellValue(intValue);
                     }
                     else if (value instanceof Long) {
                         long longValue = (Long) value;
                         cell.setCellValue(longValue);
                     }
                     else if (value instanceof Boolean) {
                        boolean bValue = (Boolean) value;
                        textValue = "1";
                        if (!bValue) {
                            textValue = "0";
                        }
                    } else if (value instanceof Date) {
                        Date date = (Date) value;
                        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
                        textValue = sdf.format(date);
                    } else {
                        // 其它数据类型都当作字符串简单处理
                        if(value == null){
                            textValue = "";
                        } else {
                            textValue = value.toString();
                        }
                            
                    }
                    
                    if (textValue != null) {
                        Pattern p = Pattern.compile("^//d+(//.//d+)?$");
                        Matcher matcher = p.matcher(textValue);
                        if (matcher.matches()) {
                            // 是数字当作double处理
                            cell.setCellValue(Double.parseDouble(textValue));
                        } else {
                            HSSFRichTextString richString = new HSSFRichTextString(
                                    textValue);
                            richString.applyFont(font);
                            cell.setCellValue(richString);
                        }
                    }
                } catch (SecurityException e) {
                    e.printStackTrace();
                } catch (NoSuchMethodException e) {
                    e.printStackTrace();
                } catch (IllegalArgumentException e) {
                    e.printStackTrace();
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                } catch (InvocationTargetException e) {
                    e.printStackTrace();
                } finally {
                    // 清理资源
                }
            }

        }
        try {
            workbook.write(out);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }