Apache Poi 简明教程

Apache POI - Spreadsheets

本章介绍了如何创建电子表格以及使用 Java 操纵它。电子表格是 Excel 文件中的一页；它包含具有特定名称的行和列。

完成本章学习后，您将能够创建电子表格并对其执行读取操作。

Create a Spreadsheet

首先，我们使用前面章节中讨论的引用类创建电子表格。按照上一章节，首先创建一个工作簿，然后再创建一张工作表。

以下代码片段用于创建电子表格。

//Create Blank workbook
XSSFWorkbook workbook = new XSSFWorkbook();

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

Rows on Spreadsheet

电子表格具有网格布局。行和列使用特定名称进行标识。列使用字母标识，行使用数字标识。

以下代码片段用于创建行。

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

Write into a Spreadsheet

让我们考虑一个员工数据示例。此处，员工数据采用表格形式给出。

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

以下代码用于将上述数据写入电子表格。

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");
   }
}

将上述 Java 代码保存为 Writesheet.java ，然后在命令提示符中将其编译并运行，如下所示：

$javac Writesheet.java
$java Writesheet

它将编译和执行以在当前目录中生成一个名为 Writesheet.xlsx 的 Excel 文件，您将在命令提示符中获得以下输出。

Writesheet.xlsx written successfully

Writesheet.xlsx 文件如下所示：

writesheet

Read from a Spreadsheet

让我们将上述名为 Writesheet.xslx 的 Excel 文件视为输入。观察以下代码；它用于读取电子表格中的数据。

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 NUMERIC:
                  System.out.print(cell.getNumericCellValue() + " \t\t ");
                  break;

               case STRING:
                  System.out.print(
                  cell.getStringCellValue() + " \t\t ");
                  break;
            }
         }
         System.out.println();
      }
      fis.close();
   }
}

让我们将上述代码保存在 Readsheet.java 文件中，然后在命令提示符中将其编译并运行，如下所示：

$javac Readsheet.java
$java Readsheet

如果系统环境配置了 POI 库，它将编译和执行以在命令提示符中生成以下输出。

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