Apache Poi 创建电子表格

本章将介绍如何创建一个电子表格，并使用Java操纵它。电子表格是在Excel文件中的页面;它包含具有特定名称的行和列。

读完本章后，将能够创建一个电子表格，并能在其上执行读取操作。

创建电子表格

首先，让我们创建一个使用在前面的章节中讨论的引用的类的电子表格。按照前面的章节中，首先创建一个工作簿，然后我们就可以去，并创建一个表。

下面的代码片段用于创建电子表格。

//Create Blank workbookXSSFWorkbook workbook = new XSSFWorkbook(); //Create a blank spreadsheetXSSFSheet spreadsheet = workbook.createSheet("Sheet Name");

在电子表格的行

电子表格有一个网格布局。行和列被标识与特定的名称。该列标识字母和行用数字。

下面的代码片段用于创建一个行。

XSSFRow row = spreadsheet.createRow((short)1);

写入到电子表格

让我们考虑雇员数据的一个例子。这里的雇员数据给出以表格形式。

Emp IdEmp Name称号Tp01GopalTechnical ManagerTP02ManishaProof ReaderTp03MasthanTechnical WriterTp04SatishTechnical WriterTp05KrishnaTechnical Writer

以下代码是用来写上述数据到电子表格。

import java.io.File;import java.io.FileOutputStream;import java.util.Map;import java.util.Set;import java.util.TreeMap;import org.apache.poi.ss.usermodel.Cell;import org.apache.poi.xssf.usermodel.XSSFRow;import org.apache.poi.xssf.usermodel.XSSFSheet;import org.apache.poi.xssf.usermodel.XSSFWorkbook;public class Writesheet {   public static void main(String[] args) throws Exception    {      //Create blank workbook      XSSFWorkbook workbook = new XSSFWorkbook();       //Create a blank sheet      XSSFSheet spreadsheet = workbook.createSheet(       " Employee Info ");      //Create row object      XSSFRow row;      //This data needs to be written (Object[])      Map < String, Object[] > empinfo =       new TreeMap < String, Object[] >();      empinfo.put( "1", new Object[] {       "EMP ID", "EMP NAME", "DESIGNATION" });      empinfo.put( "2", new Object[] {       "tp01", "Gopal", "Technical Manager" });      empinfo.put( "3", new Object[] {       "tp02", "Manisha", "Proof Reader" });      empinfo.put( "4", new Object[] {       "tp03", "Masthan", "Technical Writer" });      empinfo.put( "5", new Object[] {       "tp04", "Satish", "Technical Writer" });      empinfo.put( "6", new Object[] {       "tp05", "Krishna", "Technical Writer" });      //Iterate over data and write to sheet      Set < String > keyid = empinfo.keySet();      int rowid = 0;      for (String key : keyid)      {         row = spreadsheet.createRow(rowid++);         Object [] objectArr = empinfo.get(key);         int cellid = 0;         for (Object obj : objectArr)         {            Cell cell = row.createCell(cellid++);            cell.setCellValue((String)obj);         }      }      //Write the workbook in file system      FileOutputStream out = new FileOutputStream(       new File("Writesheet.xlsx"));      workbook.write(out);      out.close();      System.out.println(       "Writesheet.xlsx written successfully" );   }}

上面的Java代码保存为Writesheet.java，然后并在命令提示符下编译运行，如下所示：

$javac Writesheet.java$java Writesheet

这将编译和执行来生成一个Excel文件名为Writesheet.xlsx在当前目录中，在命令提示符处键入以下输出。

Writesheet.xlsx written successfully

Writesheet.xlsx文件的内容如下所示。

从电子表格读取数据

让我们考虑上述excel文件命名Writesheet.xslx作为输入文件。注意下面的代码;它是用于从电子表格中读取数据。

import java.io.File;import java.io.FileInputStream;import java.util.Iterator;import org.apache.poi.ss.usermodel.Cell;import org.apache.poi.ss.usermodel.Row;import org.apache.poi.xssf.usermodel.XSSFRow;import org.apache.poi.xssf.usermodel.XSSFSheet;import org.apache.poi.xssf.usermodel.XSSFWorkbook;public class Readsheet {   static XSSFRow row;   public static void main(String[] args) throws Exception    {      FileInputStream fis = new FileInputStream(      new File("WriteSheet.xlsx"));      XSSFWorkbook workbook = new XSSFWorkbook(fis);      XSSFSheet spreadsheet = workbook.getSheetAt(0);      Iterator < Row > rowIterator = spreadsheet.iterator();      while (rowIterator.hasNext())       {         row = (XSSFRow) rowIterator.next();         Iterator < Cell > cellIterator = row.cellIterator();         while ( cellIterator.hasNext())          {            Cell cell = cellIterator.next();            switch (cell.getCellType())             {               case Cell.CELL_TYPE_NUMERIC:               System.out.print(                cell.getNumericCellValue() + " \t\t " );               break;               case Cell.CELL_TYPE_STRING:               System.out.print(               cell.getStringCellValue() + " \t\t " );               break;            }         }         System.out.println();      }      fis.close();   }}

让我们把上面的代码保存在Readsheet.java文件，然后编译并在命令提示符下运行，如下所示：

$javac Readsheet.java$java Readsheet

如果您的系统环境配置了POI库，它会编译和执行产生在命令提示符处键入以下输出。

EMP ID EMP NAME DESIGNATION  tp01   Gopal    Technical Manager  tp02   Manisha  Proof Reader  tp03   Masthan  Technical Writer  tp04   Satish   Technical Writer  tp05   Krishna  Technical Writer