Apache POI 讀寫 Excel 文件

目錄

• 寫入 Excel 文件
• 讀取 Excel 文件
• 遍歷 Excel 文件
• 須要的 maven 依賴
• 完整代碼

寫入 Excel 文件

// 寫入 Excel 文件
// ============================================================================== //
Workbook wb = new HSSFWorkbook(); // or Workbook wb = new XSSFWorkbook();

// Create a sheet.
Sheet sheet = wb.createSheet("The Name of the Sheet");

// Create a row and put some cells in it. Rows are 0 based.
Row row = sheet.createRow(0);

// Create a cell and put a value in it.
Cell cell = row.createCell(0);
cell.setCellValue("Let me have a try!");

// Or do it on one line.
row.createCell(1).setCellValue("Let me have a try!");

/*
備註：
try (...) {
    ...
}
上述的表達可以在全部語句執行完以後自動釋放括號中的資源。
*/
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) { // or workbook.xlsx
    wb.write(fileOut);
} catch (FileNotFoundException e) {
    System.out.println("The path is not correct!!!");
    System.exit(-1);
} catch (IOException e) {
    e.printStackTrace();
}

讀取 Excel 文件

// 讀取 Excel 文件到 Workbook 對象中
// ============================================================================== //

/*
使用 File 對象比使用 InputStream 對象所需的內存資源更少，由於使用 InputStream 對象
須要將整個文件緩存到內存中。
 */

// Use a file
try {
    Workbook wb = WorkbookFactory.create(new File("MyExcel.xls")); // or MyExcel.xlsx
} catch (IOException e) {
    e.printStackTrace();
} catch (InvalidFormatException e) {
    e.printStackTrace();
}

// Use an InputStream, needs more memory
try (InputStream in = new FileInputStream("MyExcel.xls")) { // or MyExcel.xlsx
    Workbook wb = WorkbookFactory.create(in);
} catch (FileNotFoundException e) {
    System.out.println("The file does not exist or the path is not correct!!!");
} catch (IOException e) {
    e.printStackTrace();
} catch (InvalidFormatException e) {
    e.printStackTrace();
}

遍歷 Excel 文件

// 遍歷 Excel
// ============================================================================== //
try {
    Workbook wb = WorkbookFactory.create(new File("MyExcel.xls")); // or MyExcel.xlsx

    for (Sheet sheet : wb) {
        for (Row row : sheet) {
            for (Cell cell : row) {
                // pass
            }
        }
    }
} catch (IOException e) {
    e.printStackTrace();
} catch (InvalidFormatException e) {
    e.printStackTrace();
}

須要的 maven 依賴

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>3.17</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>3.17</version>
</dependency>

完整代碼

package ai.labrador.poi.excel;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.*;

import java.io.*;

/**
 * 學習使用 HSSF 或者 XSSF 讀寫 Excel 文件
 * Reference:
 * [Busy Developers' Guide to HSSF and XSSF Features](http://poi.apache.org/spreadsheet/quick-guide.html#NewWorkbook)
 *
 * @author  Genpeng Xu
 * @date    2018/06/05
 */
public class LearnHSSFAndXSSF {
    public static void main(String[] args) {

        // 寫入 Excel 文件
        // ============================================================================== //
        Workbook wb = new HSSFWorkbook(); // or Workbook wb = new XSSFWorkbook();

        // Create a sheet.
        Sheet sheet = wb.createSheet("The Name of the Sheet");

        // Create a row and put some cells in it. Rows are 0 based.
        Row row = sheet.createRow(0);

        // Create a cell and put a value in it.
        Cell cell = row.createCell(0);
        cell.setCellValue("Let me have a try!");

        // Or do it on one line.
        row.createCell(1).setCellValue("Let me have a try!");

        /*
        備註：
        try (...) {
            ...
        }
        上述的表達可以在全部語句執行完以後自動釋放括號中的資源。
         */
        try (OutputStream fileOut = new FileOutputStream("workbook.xls")) { // or workbook.xlsx
            wb.write(fileOut);
        } catch (FileNotFoundException e) {
            System.out.println("The path is not correct!!!");
            System.exit(-1);
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 讀取 Excel 文件到 Workbook 對象中
        // ============================================================================== //

        /*
        使用 File 對象比使用 InputStream 對象所需的內存資源更少，由於使用 InputStream 對象
        須要將整個文件緩存到內存中。
         */

        // Use a file
        try {
            Workbook wb = WorkbookFactory.create(new File("MyExcel.xls")); // or MyExcel.xlsx
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InvalidFormatException e) {
            e.printStackTrace();
        }

        // Use an InputStream, needs more memory
        try (InputStream in = new FileInputStream("MyExcel.xls")) { // or MyExcel.xlsx
            Workbook wb = WorkbookFactory.create(in);
        } catch (FileNotFoundException e) {
            System.out.println("The file does not exist or the path is not correct!!!");
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InvalidFormatException e) {
            e.printStackTrace();
        }

        // 遍歷 Excel
        // ============================================================================== //
        try {
            Workbook wb = WorkbookFactory.create(new File("MyExcel.xls")); // or MyExcel.xlsx

            for (Sheet sheet : wb) {
                for (Row row : sheet) {
                    for (Cell cell : row) {
                        // pass
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InvalidFormatException e) {
            e.printStackTrace();
        }
    }
}