//下面是用來生成Excel資料的Servlet，在web.xml中對映成 /data.xls

import java.io.IOException;

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

import com.carlease.persist.ExportDataDao;

public class ExportDataServlet extends HttpServlet {

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

  this.doPost(request, response);
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  request.setCharacterEncoding("utf-8");

 //獲得要生成Excel資料的資料庫中的表名稱
  String tableName = request.getParameter("tableName");
  
  // 禁止資料快取。
  response.setHeader("Pragma", "no-cache");
  response.setHeader("Cache-Control", "no-cache");
  response.setDateHeader("Expires", 0);

  // 設定響應的型別格式為電子表格格式
  response.setContentType("application/vnd.ms-excel;charset=utf-8");

  // 將資料輸出到Servlet輸出流中。
  ServletOutputStream sos = response.getOutputStream();

 //這是一個用來處理從資料庫中讀取資料的Dao操作類
  ExportDataDao edd = new ExportDataDao();
  edd.outDB(tableName, sos);
  sos.flush();
  sos.close();
 }

 
}

//操作讀取資料庫的Dao類

import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletOutputStream;

import com.carlease.common.DBManager;

public class ExportDataDao {

 public ExportDataDao(){
 }

 public void outDB(String tableName, ServletOutputStream sos) {

  DBManager dbm = new DBManager();
  Connection con = dbm.getCon();

  ResultSetMetaData rsmd = null;
  Statement smt = null;
  ResultSet rs = null;

  String sql = "select * from " + tableName;
  try {
   smt = con.createStatement();
   rs = smt.executeQuery(sql);
   rsmd = rs.getMetaData();

   // 輸出表頭資訊一共有多少列
   int colNum = rsmd.getColumnCount();
   StringBuffer sbt = new StringBuffer();
   for (int i = 1; i <= colNum; i++) {
    sbt.append(rsmd.getColumnName(i) + "\t");
   }
   sos.println(sbt.toString());

   // 輸出資訊體，總共有多少條資料
   while (rs.next()) {
    StringBuffer sb = new StringBuffer();
    for (int i = 1; i <= colNum; i++) {
     sb.append(rs.getString(rsmd.getColumnName(i)) + "\t");
    }
    sos.println(sb.toString());
   }
  } catch (SQLException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }

 /**
  * 獲得當前使用者下的所有表名稱
  *
  * @return 裝有所有表名稱的List集合
  */
 public List<String> getAllTable(){
  List<String> tableList = new ArrayList<String>();
  DBManager dbm = new DBManager();
  Connection con = dbm.getCon();
  Statement smt = null;
  ResultSet rs = null;
  try {
   //獲取Oracle資料庫當前使用者下的所有表名的特定語句
   String sql = "select table_name from user_tables";
   smt = con.createStatement();
   rs = smt.executeQuery(sql);
   while(rs.next()){
    tableList.add(rs.getString("table_name"));
   }
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   dbm.close(rs, smt, con);
  }
  
  return tableList;
 }

}