雷林鹏分享：Apache POI电子表格/Spreadsheet
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 workbook
XSSFWorkbook workbook = new XSSFWorkbook();
//Create a blank spreadsheet
XSSFSheet spreadsheet = workbook.createSheet("Sheet Name");
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 Manager
TP02ManishaProof Reader
Tp03MasthanTechnical Writer
Tp04SatishTechnical Writer
Tp05KrishnaTechnical 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
(编辑：雷林鹏 来源：网络|侵删)