本章介紹了POI庫與數據庫的交互方式。有了JDBC幫助,可以從數據庫中檢索數據並插入數據來使用POI庫電子表格。讓我們考慮SQL操作MySQL數據庫。
寫入數據庫
讓我們假設數據表是 emp_tbl 存有僱員信息是從MySQL數據庫 test 中檢索。
EMP IDEMP NAMEDEGSALARYDEPT
1201GopalTechnical Manager45000IT
1202ManishaProof reader45000Testing
1203MasthanvaliTechnical Writer45000IT
1204KiranHr Admin40000HR
1205KranthiOp Admin30000
使用下面的代碼從數據庫中檢索數據,並插入到同一個電子表格。
import java.io.File;
import java.io.FileOutputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class ExcelDatabase
{
public static void main(String[] args) throws Exception
{
Class.forName("com.mysql.jdbc.Driver");
Connection connect = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/test" ,
"root" ,
"root"
);
Statement statement = connect.createStatement();
ResultSet resultSet = statement
.executeQuery("select * from emp_tbl");
XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet spreadsheet = workbook
.createSheet("employe db");
XSSFRow row=spreadsheet.createRow(1);
XSSFCell cell;
cell=row.createCell(1);
cell.setCellValue("EMP ID");
cell=row.createCell(2);
cell.setCellValue("EMP NAME");
cell=row.createCell(3);
cell.setCellValue("DEG");
cell=row.createCell(4);
cell.setCellValue("SALARY");
cell=row.createCell(5);
cell.setCellValue("DEPT");
int i=2;
while(resultSet.next())
{
row=spreadsheet.createRow(i);
cell=row.createCell(1);
cell.setCellValue(resultSet.getInt("eid"));
cell=row.createCell(2);
cell.setCellValue(resultSet.getString("ename"));
cell=row.createCell(3);
cell.setCellValue(resultSet.getString("deg"));
cell=row.createCell(4);
cell.setCellValue(resultSet.getString("salary"));
cell=row.createCell(5);
cell.setCellValue(resultSet.getString("dept"));
i++;
}
FileOutputStream out = new FileOutputStream(
new File("exceldatabase.xlsx"));
workbook.write(out);
out.close();
System.out.println(
"exceldatabase.xlsx written successfully");
}
}
讓我們保存了上面的代碼爲ExcelDatabase.java。編譯並從命令提示符執行它如下。
$javac ExcelDatabase.java
$java ExcelDatabase
它會生成一個名爲exceldatabase.xlsx在當前目錄中的Excel文件並顯示在命令提示符處輸出以下。
exceldatabase.xlsx written successfully
exceldatabase.xlsx文件如下所示。
(編輯:雷林鵬 來源:網絡|侵刪)