java jxl 向Excel中追加数据而不覆盖原来数据的例子

向先原来就有数据的Excel写数据是不会覆盖原有的数据，只是在追加数据。

public class Excel {

    public Excel() {

    }

    public void CreateWorkbook(File file, double[] a) {

        try {

            if (!file.exists()) { //判断文件是否已存在，如果没有存在则创建新文件

                jxl.write.WritableWorkbook wwb = Workbook.createWorkbook(new

                        File("result.xls"

                        ));

                jxl.write.WritableSheet ws = wwb.createSheet("Test Sheet 1", 0);

                int i = 0;

                ws.setColumnView(0, 20); //设置列宽

                jxl.write.NumberFormat nf = new jxl.write.NumberFormat(

                        "0.0000000000000000"); //定义数值格式

                WritableCellFormat wcfN = new WritableCellFormat(nf);

                String str2 = "第" + 1 + "次试验";

                Label label = new Label(0, 0, str2);

                ws.addCell(label);

                while (i < a.length) {

                    jxl.write.Number num = new jxl.write.Number(0, i + 1,

                            a[i], wcfN);

                    ws.addCell(num);

                    i++;

                }

                //写入Exel工作表

                wwb.write();

                //关闭Excel工作薄对象

                wwb.close();

            } else {

                Workbook rwb = Workbook.getWorkbook(file);

                File tempfile = new File(System.getProperty("user.dir") +

                                         "\\tempfile.xls");

                WritableWorkbook wwb = Workbook.createWorkbook(tempfile, rwb);

                WritableSheet ws = wwb.getSheet(0);

                int num = rwb.getSheet(0).getColumns();

                int num1 = num + 1;

                ws.setColumnView(num, 20); //设置列宽

                String str2 = "第" + num1 + "次试验"; //添加列名

                Label label = new Label(num, 0, str2);

                ws.addCell(label);

                int i = 0;

                jxl.write.NumberFormat nf = new jxl.write.NumberFormat(

                        "0.000000000000000"); //定义数值格式

                WritableCellFormat wcfN = new WritableCellFormat(nf);

                while (i < a.length) {

                    jxl.write.Number number = new jxl.write.Number(num,

                            i + 1,

                            a[i], wcfN);

                    ws.addCell(number);

                    i++;

                }

                wwb.write();

                wwb.close();

                rwb.close();

                String filename = file.getPath();

                System.out.println("filename:" + filename);

                file.delete();

                tempfile.renameTo(file);

                System.out.println("tempfile:" + tempfile.getPath());

                System.out.println(tempfile.exists());

                System.out.println(file.exists());

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}