写使用POI的现有xls文件 [英] Writing to a existing xls file using POI

问题描述

该方案大致是这样的：

我有几种方法Java程序获取调用随机。

I have a java program with several methods getting called randomly.

第一种方法将创建使用Apache POI XLS文件，并会将头的列。

The first method will create an xls file using apache POI and will put the headers for the columns.

所有其他方法有一个记录写入该文件。

All the other methods has to write a record into this file.

最后一个方法将第一封邮件创建XLS，然后删除XLS。

The final method will first mail the created xls and then delete the xls.

有关上述场景下面的方法正确的：

For above scenario is the below approach correct:

1）创建文件，把标题名中的第一种方法：

1) Create the file and put the header names in the first method:

Workbook wb = new HSSFWorkbook();
CreationHelper createHelper = wb.getCreationHelper();
Sheet sheet = wb.createSheet("First Sheet");
Row row = sheet.createRow((short)0);
row.createCell(1).setCellValue(createHelper.createRichTextString("First Column"));
row.createCell(2).setCellValue(createHelper.createRichTextString("Second Column"));
row.createCell(3).setCellValue(createHelper.createRichTextString("Third Column"));

// Write the output to a file
FileOutputStream fileOut = new FileOutputStream("workbook.xls");
wb.write(fileOut);
fileOut.close();

2），在余下的方法把记录：

2) In the remaining methods put the records:

我不知道的code在这里。我知道我能达到使用getRowCount方法表的末尾，然后添加新行。但是，我找不到任何例如code。

I am not sure of the code here. I know that I can reach the end of the sheet using getRowCount method and then add the new row. But I could not find any example code.

另外，如何访问现有的XLS文件？

Also, how to access the existing xls file ?

3）在过去的方法，该文件将被邮寄，然后删除。

3) In the last method, the file will be mailed and then deleted.

我是否需要删除文件前执行任何其他步骤？

Do I need to perform any other steps before deleting the file ?

推荐答案

这就是我一直在寻找：

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;   
import org.apache.poi.ss.usermodel.CreationHelper;
import org.apache.poi.ss.usermodel.Font;
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;

public class PoiWriteExcelFile {

public void methodOne() {

    System.out.println("Into method one!");

    Workbook wb = new HSSFWorkbook();
    Font f = wb.createFont();
    f.setBoldweight(Font.BOLDWEIGHT_BOLD);
    CellStyle cs = wb.createCellStyle();
    cs.setFont(f);

    CreationHelper createHelper = wb.getCreationHelper();
    Sheet sheet = wb.createSheet("First Sheet");
    Row row = sheet.createRow((short) 0);

    Cell c = null;

    c = row.createCell(0);
    c.setCellStyle(cs);
    c.setCellValue(createHelper.createRichTextString("First Column"));

    c = row.createCell(1);
    c.setCellStyle(cs);
    c.setCellValue(createHelper.createRichTextString("Second Column"));

    c = row.createCell(2);
    c.setCellStyle(cs);
    c.setCellValue(createHelper.createRichTextString("Third Column"));

    // Write the output to a file
    FileOutputStream fileOut;
    try {
        fileOut = new FileOutputStream("C:\\TestData\\POI\\poi-test.xls");
        wb.write(fileOut);
        fileOut.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    System.out.println("Out of method one!");

}

public void methodTwo() {

    System.out.println("Into method two!");
    InputStream inp;
    try {
        inp = new FileInputStream("C:\\TestData\\POI\\poi-test.xls");
        Workbook wb = WorkbookFactory.create(inp);
        Sheet sheet = wb.getSheetAt(0);
        Row row = sheet.createRow((short) (sheet.getLastRowNum() + 1));

        Cell c = null;
        CreationHelper createHelper = wb.getCreationHelper();

        c = row.createCell(0);
        c.setCellValue(createHelper.createRichTextString("First Row First value"));

        c = row.createCell(1);
        c.setCellValue(createHelper.createRichTextString("First Row Second value"));

        c = row.createCell(2);
        c.setCellValue(createHelper.createRichTextString("First Row Third value"));

        FileOutputStream fileOut = new FileOutputStream("C:\\TestData\\POI\\poi-test.xls");
        wb.write(fileOut);
        fileOut.close();

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (InvalidFormatException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }


    System.out.println("Out of method two!");
}

public void methodThree() {

    System.out.println("Into method three!");
    InputStream inp;
    try {
        inp = new FileInputStream("C:\\TestData\\POI\\poi-test.xls");
        Workbook wb = WorkbookFactory.create(inp);
        Sheet sheet = wb.getSheetAt(0);
        Row row = sheet.createRow((short) (sheet.getLastRowNum() + 1));

        Cell c = null;
        CreationHelper createHelper = wb.getCreationHelper();

        c = row.createCell(0);
        c.setCellValue(createHelper.createRichTextString("Second Row First value"));

        c = row.createCell(1);
        c.setCellValue(createHelper.createRichTextString("Second Row Second value"));

        c = row.createCell(2);
        c.setCellValue(createHelper.createRichTextString("Second Row Third value"));

        FileOutputStream fileOut = new FileOutputStream("C:\\TestData\\POI\\poi-test.xls");
        wb.write(fileOut);
        fileOut.close();

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (InvalidFormatException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    System.out.println("Out of method three!");

}

public void methodFour() {

    System.out.println("Into method four!");
    File file = new File("C:\\TestData\\POI\\poi-test.xls");
    // file.deleteOnExit();
    System.out.println("Out of method four!");

}

public static void main(final String[] args) {

    PoiWriteExcelFile myObj = new PoiWriteExcelFile();
    myObj.methodOne();
    myObj.methodTwo();
    myObj.methodThree();
    myObj.methodFour();

}

}

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