本章將介紹如何創建一個電子表格，並使用Java操縱它。電子表格是在Excel文件中的頁麵;它包含具有特定名稱的行和列。

讀完本章後，將能夠創建一個電子表格，並能在其上執行讀取操作。

創建電子表格

首先，讓我們創建一個使用在前麵的章節中討論的引用的類的電子表格。按照前麵的章節中，首先創建一個工作簿，然後我們就可以去，並創建一個表。

下麵的代碼片段用於創建電子表格。

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

在電子表格的行

電子表格有一個網格布局。行和列被標識與特定的名稱。該列標識字母和行用數字。

下麵的代碼片段用於創建一個行。

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

寫入到電子表格

讓我們考慮雇員數據的一個例子。這裡的雇員數據給出以表格形式。

Emp Id	Emp Name	稱號
Tp01	Gopal	Technical Manager
TP02	Manisha	Proof Reader
Tp03	Masthan	Technical Writer
Tp04	Satish	Technical Writer
Tp05	Krishna	Technical Writer

以下代碼是用來寫上述數據到電子表格。

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" );
   }
}

上麵的Java代碼保存為Writesheet.java，然後並在命令提示符下編譯運行，如下所示：

$javac Writesheet.java
$java Writesheet

這將編譯和執行來生成一個Excel文件名為Writesheet.xlsx在當前目錄中，在命令提示符處鍵入以下輸出。

Writesheet.xlsx written successfully

Writesheet.xlsx文件的內容如下所示。

從電子表格讀取數據

讓我們考慮上述excel文件命名Writesheet.xslx作為輸入文件。注意下麵的代碼;它是用於從電子表格中讀取數據。

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();
   }
}

讓我們把上麵的代碼保存在Readsheet.java文件，然後編譯並在命令提示符下運行，如下所示：

$javac Readsheet.java
$java Readsheet

如果您的係統環境配置了POI庫，它會編譯和執行產生在命令提示符處鍵入以下輸出。

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