导出数据库数据到Excel

做了一个利用POI导出数据库数据到Excel的例子，并把这个例子与大家一起分享，一起学习，共同进步！
先简单介绍一下poi，poi是apache组织的一个开源项目，最新版为poi-3.0.1,要使用poi需要到apache网站下载poi-bin3.0.1.zip压缩包，并将poi-3.0.1.jar加入到项目的ClassPath中。

下面是完成这个实例的步骤：

1、建立好一个web工程：poi；

2、导入所需要的jar包:poi-3.0.1.jar和mysql数据库驱动包；

3、编写一个StudentResultSet类，用于取出数据库中的数据；

 packageorg.hnylj.poi;

 importjava.sql.Connection;
 importjava.sql.DriverManager;
 importjava.sql.PreparedStatement;
 importjava.sql.ResultSet;
 importjava.sql.SQLException;

 publicclassStudentResultSet{
 privateConnectionconn;
 privatePreparedStatementpstmt;
 privateResultSetrs;
 privatestaticfinalStringDRIVER="com.mysql.jdbc.Driver";
 privatestaticfinalStringURL="jdbc:mysql://localhost:3306/poi";
 privatestaticfinalStringUSERNAME="root";
 privatestaticfinalStringPASSWORD="123";

 //查询数据库中的数据
 publicResultSetquery(){
 try{
 Class.forName(DRIVER);
 conn=DriverManager.getConnection(URL,USERNAME,PASSWORD);
 pstmt=conn.prepareStatement("select*fromstudent");
 rs=pstmt.executeQuery();
 }catch(ClassNotFoundExceptione){
 e.printStackTrace();
 }catch(SQLExceptione){
 e.printStackTrace();
 }
 returnrs;
 }
}

package org.hnylj.poi;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class StudentResultSet {
	private Connection conn;
	private PreparedStatement pstmt;
	private ResultSet rs;
	private static final String DRIVER = "com.mysql.jdbc.Driver";
	private static final String URL = "jdbc:mysql://localhost:3306/poi";
	private static final String USERNAME = "root";
	private static final String PASSWORD = "123";
    
	//查询数据库中的数据
	public ResultSet query() {
		try {
			Class.forName(DRIVER);
			conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
			pstmt = conn.prepareStatement("select * from student");
			rs = pstmt.executeQuery();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return rs;
	}
}

4、编写一个BuildExcelServlet，用于生成Excel；

 packageorg.hnylj.poi;

 importjava.io.FileOutputStream;
 importjava.io.IOException;
 importjava.sql.ResultSet;
 importjava.sql.ResultSetMetaData;

 importjavax.servlet.ServletException;
 importjavax.servlet.http.HttpServlet;
 importjavax.servlet.http.HttpServletRequest;
 importjavax.servlet.http.HttpServletResponse;

 importorg.apache.poi.hssf.usermodel.HSSFCell;
 importorg.apache.poi.hssf.usermodel.HSSFRichTextString;
 importorg.apache.poi.hssf.usermodel.HSSFRow;
 importorg.apache.poi.hssf.usermodel.HSSFSheet;
 importorg.apache.poi.hssf.usermodel.HSSFWorkbook;

 publicclassBuildExcelServletextendsHttpServlet{

 protectedvoiddoGet(HttpServletRequestrequest,
 HttpServletResponseresponse)throwsServletException,IOException{
 StudentResultSetstuResultSet=newStudentResultSet();
 ResultSetrs=stuResultSet.query();
 StringxlsName="test.xls";
 StringsheetName="sheetName";

 HSSFWorkbookworkbook=newHSSFWorkbook();
 HSSFSheetsheet=workbook.createSheet();
 workbook.setSheetName(0,sheetName);
 HSSFRowrow=sheet.createRow((short)0);
 HSSFCellcell;
 try{
 ResultSetMetaDatamd=rs.getMetaData();
 intnColumn=md.getColumnCount();

 for(inti=1;i<=nColumn;i++){
 cell=row.createCell((short)(i-1));
 cell.setCellType(HSSFCell.CELL_TYPE_STRING);
 cell.setCellValue(newHSSFRichTextString(md.getColumnLabel(i)));
 }
 intiRow=1;
 while(rs.next()){
 row=sheet.createRow((short)iRow);
 ;
 for(intj=1;j<=nColumn;j++){
 cell=row.createCell((short)(j-1));
 cell.setCellType(HSSFCell.CELL_TYPE_STRING);
 cell.setCellValue(newHSSFRichTextString(rs.getObject(j)
 .toString()));
 }
 iRow++;
 }
 Stringfilename=request.getRealPath("/")+xlsName;
 request.setAttribute("filename",filename);
 FileOutputStreamfOut=newFileOutputStream(filename);
 workbook.write(fOut);
 fOut.flush();
 fOut.close();
 request.getRequestDispatcher("OpenExcelServlet").forward(request,
 response);
 }catch(Exceptione){
 e.printStackTrace();
 }
 }

 protectedvoiddoPost(HttpServletRequestrequest,
 HttpServletResponseresponse)throwsServletException,IOException{
 this.doGet(request,response);
 }
}

package org.hnylj.poi;

import java.io.FileOutputStream;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRichTextString;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

public class BuildExcelServlet extends HttpServlet {

	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		StudentResultSet stuResultSet = new StudentResultSet();
		ResultSet rs = stuResultSet.query();
		String xlsName = "test.xls";
		String sheetName = "sheetName";

		HSSFWorkbook workbook = new HSSFWorkbook();
		HSSFSheet sheet = workbook.createSheet();
		workbook.setSheetName(0, sheetName);
		HSSFRow row = sheet.createRow((short) 0);
		HSSFCell cell;
		try {
			ResultSetMetaData md = rs.getMetaData();
			int nColumn = md.getColumnCount();

			for (int i = 1; i <= nColumn; i++) {
				cell = row.createCell((short) (i - 1));
				cell.setCellType(HSSFCell.CELL_TYPE_STRING);
				cell.setCellValue(new HSSFRichTextString(md.getColumnLabel(i)));
			}
			int iRow = 1;
			while (rs.next()) {
				row = sheet.createRow((short) iRow);
				;
				for (int j = 1; j <= nColumn; j++) {
					cell = row.createCell((short) (j - 1));
					cell.setCellType(HSSFCell.CELL_TYPE_STRING);
					cell.setCellValue(new HSSFRichTextString(rs.getObject(j)
							.toString()));
				}
				iRow++;
			}
			String filename = request.getRealPath("/") + xlsName;
			request.setAttribute("filename", filename);
			FileOutputStream fOut = new FileOutputStream(filename);
			workbook.write(fOut);
			fOut.flush();
			fOut.close();
			request.getRequestDispatcher("OpenExcelServlet").forward(request,
					response);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		this.doGet(request, response);
	}
}

5、编写一个OpenExcelServlet，用于把生成的Excel在页面上打开；

 packageorg.hnylj.poi;

 importjava.io.BufferedInputStream;
 importjava.io.FileInputStream;
 importjava.io.IOException;
 importjava.io.PrintWriter;

 importjavax.servlet.ServletException;
 importjavax.servlet.http.HttpServlet;
 importjavax.servlet.http.HttpServletRequest;
 importjavax.servlet.http.HttpServletResponse;

 publicclassOpenExcelServletextendsHttpServlet{

 publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)
 throwsServletException,IOException{

 response.setContentType("application/vnd.ms-excel");
 PrintWriterout=response.getWriter();
 StringfilePath=(String)request.getAttribute("filename");
 BufferedInputStreambis=null;
 try{
 bis=newBufferedInputStream(newFileInputStream(filePath));
 intbytesRead;
 while((bytesRead=bis.read())!=-1){
 out.write(bytesRead);
 out.flush();
 }
 }catch(IOExceptione){
 e.printStackTrace();
 }finally{
 if(bis!=null)
 bis.close();
 if(out!=null)
 out.close();
 }
 }

 publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)
 throwsServletException,IOException{
 this.doGet(request,response);
 }
}

package org.hnylj.poi;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class OpenExcelServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("application/vnd.ms-excel");
		PrintWriter out = response.getWriter();
		String filePath = (String) request.getAttribute("filename");
		BufferedInputStream bis = null;
		try {
			bis = new BufferedInputStream(new FileInputStream(filePath));
			int bytesRead;
			while ((bytesRead = bis.read()) != -1) {
				out.write(bytesRead);
				out.flush();
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (bis != null)
				bis.close();
			if (out != null)
				out.close();
		}
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doGet(request, response);
	}
}

6、在web.xml里配置一下servlet的映射；

 <servlet>
 <servlet-name>BuildExcelServlet</servlet-name>
 <servlet-class>org.hnylj.poi.BuildExcelServlet</servlet-class>
 </servlet>
 <servlet>
 <servlet-name>OpenExcelServlet</servlet-name>
 <servlet-class>org.hnylj.poi.OpenExcelServlet</servlet-class>
 </servlet>

 <servlet-mapping>
 <servlet-name>OpenExcelServlet</servlet-name>
 <url-pattern>/OpenExcelServlet</url-pattern>
 </servlet-mapping>

 <servlet-mapping>
 <servlet-name>BuildExcelServlet</servlet-name>
 <url-pattern>/BuildExcelServlet</url-pattern>
 </servlet-mapping>

        <servlet>
		<servlet-name>BuildExcelServlet</servlet-name>
		<servlet-class>org.hnylj.poi.BuildExcelServlet</servlet-class>
	</servlet>
	<servlet>
		<servlet-name>OpenExcelServlet</servlet-name>
		<servlet-class>org.hnylj.poi.OpenExcelServlet</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>OpenExcelServlet</servlet-name>
		<url-pattern>/OpenExcelServlet</url-pattern>
	</servlet-mapping>

	<servlet-mapping>
		<servlet-name>BuildExcelServlet</servlet-name>
		<url-pattern>/BuildExcelServlet</url-pattern>
	</servlet-mapping>

7、启动tomcat，运行程序