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使用POI让java可以操作Excel（3）

AbrahamW 2022-09-30 阅读 37
poijavaexcelicojavascript虚拟化云计算


1. 将数据批量导出至Excel（.xls）

  • 前端借助jQuery-EasyUI来实现

在jquery-easyui-1.9.4/themes/icon.css文件尾部添加

.icon-export-excel{
  background:url('icons/ExportExcel.png') no-repeat center center;
}

​​图标 ExportExcel.png 在这里​​

前端HTML示例

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>jQuery EasyUI Demo for Java</title>
        <!-- 主题可以通过themes/下的easyui.css进行更换 -->
        <link rel="stylesheet" type="text/css" href="jquery-easyui-1.9.4/themes/ui-cupertino/easyui.css">
        <link rel="stylesheet" type="text/css" href="jquery-easyui-1.9.4/themes/icon.css">
        <link rel="stylesheet" type="text/css" href="jquery-easyui-1.9.4/demo/demo.css">
        <script type="text/javascript" src="jquery-easyui-1.9.4/jquery.min.js"></script>
        <script type="text/javascript" src="jquery-easyui-1.9.4/jquery.easyui.min.js"></script>
        <script type="text/javascript" src="jquery-easyui-1.9.4/locale/easyui-lang-zh_CN.js"></script>
        <script type="text/javascript">var url;

            function deleteUser() {
                var row = $('#dg').datagrid('getSelected');
                if (row) {
                    $.messager.confirm("系统提示", "您确定要删除这条记录吗?", function(r) {
                        if (r) {
                            $.post('userDelete', {
                                delId: row.id
                            }, function(result) {
                                if (result.success) {
                                    $.messager.alert("系统提示", "已成功删除这条记录!");
                                    $("#dg").datagrid("reload"); //刷新前端
                                } else {
                                    $.messager.alert("系统提示", result.errorMsg);
                                }
                            }, 'json');
                        }
                    });
                }
            }

            function newUser() {
                $("#dlg").dialog('open').dialog('setTitle', '添加用户');
                $('#fm').form('clear');
                url = 'userSave'; //Ajax发送至后端服务器
            }


            function editUser() {
                var row = $('#dg').datagrid('getSelected');
                if (row) {
                    $("#dlg").dialog('open').dialog('setTitle', '编辑用户');
                    $('#fm').form('load', row); //加载当前行的数据
                    url = 'userSave?id=' + row.id; //Ajax发送至后端服务器
                }
            }


            function saveUser() {
                $('#fm').form('submit', {
                    url: url, //Ajax发送至后端服务器对应的url
                    onSubmit: function() {
                        return $(this).form('validate');
                    },
                    success: function(result) {
                        var result = eval（'(' + result + ')'); //转化为前端JSON
                        if (result.errorMsg) {
                            $.messager.alert("系统提示", result.errorMsg);
                            return;
                        } else {
                            $.messager.alert("系统提示", "保存成功");
                            $('#dlg').dialog('close');
                            $("#dg").datagrid("reload"); //刷新前端
                        }
                    }
                });
            }
            
            /*
             * ajax无法直接接收导出的excel。
             * 因为ajax只处理返回的字符流，而后端返回前端的excel是二进制的字节流，ajax无法处理。
             * 对于二进制的字节流只能交给浏览器来处理。
             */
            function exportUser() {
                var searchVal=$('#searchBox').val();
                console.log("查找关键字："+searchVal);
                
                if(searchVal!=""){
                    //使用window.open()方法，浏览器会“跳窗”，闪一下。
                    //window.open("exportExcel?searchKey="+searchVal);
                    window.location.href="exportExcel?searchKey="+searchVal;
                }else{
                    //window.open("exportExcel");
                    window.location.href="exportExcel";
                }
            }
            
            function searchUser(){
                var searchVal=$('#searchBox').val();
                console.log("查找关键字："+searchVal);
                if(searchVal!=''){ //查找框有输入
                   $('#dg').datagrid({
                        url:'userList',
                        queryParams: {
                            "searchVal":searchVal
                        }
                   });
                }else{ //没有输入则全量显示
                    $('#dg').datagrid({
                        url:'userList',
                        queryParams: {}
                    });
                }
            }</script>
    </head>
    <body>
        <!-- url属性表示要从Web服务器上请求数据，且与后端交互的是JSON串。交互通过Ajax（XHR）来完成。 -->
        <!-- 可以将jQuery EasyUI涉及到的组件都放在这个页面上统一调度。 -->
        <table id="dg" title="用户管理" class="easyui-datagrid"style="width:1024px;height:450px" url="userList" toolbar="#toolbar"
         pagination="true" rownumbers="true" fitColumns="true" singleSelect="true">
            <thead>
                <tr>
                    <th field="id" width="50" hidden="true">编号</th>
                    <th field="name" width="50">姓名</th>
                    <th field="phone" width="50">电话</th>
                    <th field="email" width="50">Email</th>
                    <th field="qq" width="50">QQ</th>
                </tr>
            </thead>
        </table>
        
        <div id="toolbar">
            <div>
                <a href="javascript:void(0)" class="easyui-linkbutton" iconCls="icon-add" plain="true" onclick="newUser()">添加用户</a>
                <a href="javascript:void(0)" class="easyui-linkbutton" iconCls="icon-edit" plain="true" onclick="editUser()">编辑用户</a>
                <a href="javascript:void(0)" class="easyui-linkbutton" iconCls="icon-remove" plain="true" onclick="deleteUser()">删除用户</a>
            </div>
            <div>
                <!-- href=“javascript:void(0);”意为执行一个js的空方法，这样既执行了链接动作，页面又可以不跳转。 -->
                <input id="searchBox" type="text"style="border:#87CEFA 1px solid;"/>
                <a href="javascript:void(0)" class="easyui-linkbutton" iconCls="icon-search" plain="true" onclick="searchUser()">搜索</a>
                <a href="javascript:void(0)" class="easyui-linkbutton" iconCls="icon-export-excel" plain="true" onclick="exportUser()">导出用户</a>
            </div>
        </div>

        <div id="dlg" class="easyui-dialog"style="width:400px;height:250px;padding:10px 20px" closed="true" buttons="#dlg-buttons">
            <form id="fm" method="post">
                <table cellspacing="10px;">
                    <tr>
                        <td>姓名：</td>
                        <td><input name="name" class="easyui-validatebox" required="true"style="width: 200px;"></td>
                    </tr>
                    <tr>
                        <td>联系电话：</td>
                        <td><input name="phone" class="easyui-validatebox" required="true"style="width: 200px;"></td>
                    </tr>
                    <tr>
                        <td>Email：</td>
                        <td><input name="email" class="easyui-validatebox" validType="email" required="true"style="width: 200px;"></td>
                    </tr>
                    <tr>
                        <td>QQ：</td>
                        <td><input name="qq" class="easyui-validatebox" required="true"style="width: 200px;"></td>
                    </tr>
                </table>
            </form>
        </div>

        <div id="dlg-buttons">
            <a href="javascript:void(0)" class="easyui-linkbutton" iconCls="icon-ok" onclick="saveUser()">保存</a>
            <a href="javascript:void(0)" class="easyui-linkbutton" iconCls="icon-cancel" onclick="javascript:$('#dlg').dialog('close')">关闭</a>
        </div>
    </body>
</html>

  • Dao的关键代码

public class UserDao {
  public ResultSet exportExcel(Connection con) throws Exception {
    String sql = "select * from t_user";
    PreparedStatement pstmt = con.prepareStatement(sql);
    return pstmt.executeQuery();
  }

  public ResultSet exportExcel(Connection con, String searchKey) throws Exception {
    String sql = "select * from t_user where name like ? or phone like ? or email like ? or qq like ?";
    PreparedStatement pstmt = con.prepareStatement(sql);
    pstmt.setString(1, "%" + searchKey + "%");
    pstmt.setString(2, "%" + searchKey + "%");
    pstmt.setString(3, "%" + searchKey + "%");
    pstmt.setString(4, "%" + searchKey + "%");
    return pstmt.executeQuery();
  }
  
  public ResultSet userList(Connection con, PageBean pageBean) throws Exception {
    String sql = "select * from t_user limit ?,?";
    PreparedStatement pstmt = con.prepareStatement(sql);
    pstmt.setInt(1, pageBean.getStart());
    pstmt.setInt(2, pageBean.getRows());
    return pstmt.executeQuery();
  }

  public ResultSet userList(Connection con, PageBean pageBean, String searchKey) throws Exception {
    String sql = "select * from t_user where name like ? or phone like ? or email like ? or qq like ? limit ?,?";
    PreparedStatement pstmt = con.prepareStatement(sql);
    pstmt.setString(1, "%" + searchKey + "%");
    pstmt.setString(2, "%" + searchKey + "%");
    pstmt.setString(3, "%" + searchKey + "%");
    pstmt.setString(4, "%" + searchKey + "%");
    pstmt.setInt(5, pageBean.getStart());
    pstmt.setInt(6, pageBean.getRows());
    return pstmt.executeQuery();
  }

  public int userCount(Connection con) throws Exception {
    String sql = "select count(*) as total from t_user";
    PreparedStatement pstmt = con.prepareStatement(sql);
    ResultSet rs = pstmt.executeQuery();
    if (rs.next()) {
      return rs.getInt("total");
    } else {
      return 0;
    }
  }

  public int userCount(Connection con, String searchKey) throws Exception {
    String sql = "select count(*) as total from t_user where name like ? or phone like ? or email like ? or qq like ?";
    PreparedStatement pstmt = con.prepareStatement(sql);
    pstmt.setString(1, "%" + searchKey + "%");
    pstmt.setString(2, "%" + searchKey + "%");
    pstmt.setString(3, "%" + searchKey + "%");
    pstmt.setString(4, "%" + searchKey + "%");
    ResultSet rs = pstmt.executeQuery();
    if (rs.next()) {
      return rs.getInt("total");
    } else {
      return 0;
    }
  }
......
}

  • 几个工具类

mport java.sql.ResultSet;

import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;

// 将数据库的查询结果导入Excel
public class ExcelUtil {

  public static void fillExcelData(ResultSet rs, Workbook wb, String[] headers) throws Exception {
    int rowIndex = 0;
    Sheet sheet = wb.createSheet();
    Row row = sheet.createRow(rowIndex++);
    for (int i = 0; i < headers.length; i++) {
      row.createCell(i).setCellValue(headers[i]);
    }
    while (rs.next()) {
      row = sheet.createRow(rowIndex++);
      for (int i = 0; i < headers.length; i++) {
        row.createCell(i).setCellValue(rs.getObject(i + 1).toString());
      }
    }
  }
}

import java.io.OutputStream;
import java.io.PrintWriter;

import javax.servlet.http.HttpServletResponse;

import org.apache.poi.ss.usermodel.Workbook;

public class ResponseUtil {

  //将JSON返回前端
  public static void write(HttpServletResponse response, Object o) throws Exception {
    response.setContentType("text/html;charset=utf-8");
    PrintWriter out = response.getWriter();
    out.print(o.toString());
    out.flush();
    out.close();
  }

  //将导出的Excel返回前端
  public static void export(HttpServletResponse response, Workbook wb, String fileName) throws Exception {
    response.setHeader("Content-Disposition",
        "attachment;filename=" + new String(fileName.getBytes("utf-8"), "iso8859-1"));
    response.setContentType("application/vnd.ms-excel;charset=UTF-8");
    OutputStream out = response.getOutputStream();
    wb.write(out);
    out.flush();
    out.close();
  }
}

  • 写个处理前端Excel导出请求的Servlet

web.xml

<servlet>
        <servlet-name>exportExcelServlet</servlet-name>
        <servlet-class>com.bee.web.ExportExcelServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>exportExcelServlet</servlet-name>
        <url-pattern>/exportExcel</url-pattern>
    </servlet-mapping>

Servlet

import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;

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.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Workbook;

import com.bee.dao.UserDao;
import com.bee.utils.DBUtil;
import com.bee.utils.ExcelUtil;
import com.bee.utils.ResponseUtil;

public class ExportExcelServlet extends HttpServlet {

  private static final long serialVersionUID = 1L;

  private DBUtil dbUtil = new DBUtil();
  private UserDao userDao = new UserDao();

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

  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    request.setCharacterEncoding("utf-8"); // 设定编码
    String searchKey = request.getParameter("searchKey");

    Connection con = null;
    try {
      con = dbUtil.getConnection();
      Workbook wb = new HSSFWorkbook(); //新建一个xls文件
      String[] headers = { "编号", "姓名", "电话", "Email", "QQ" };
      ResultSet rs = null;
      if (searchKey != null) {
        // HTTP GET的URL参数默认是ISO-8859-1编码
        searchKey = new String(searchKey.getBytes("ISO-8859-1"), "UTF-8");
        System.out.println("导出结果：" + searchKey);
        rs = userDao.exportExcel(con, searchKey);
      } else {
        rs = userDao.exportExcel(con);
      }
      ExcelUtil.fillExcelData(rs, wb, headers); // 得到wb
      ResponseUtil.export(response, wb, searchKey != null ? "导出搜索结果（" + searchKey + "）.xls" : "导出全量.xls");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      try {
        dbUtil.closeConnection(con);
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }
}

  • 处理easyui-datagrid组件显示的Servlet

import java.io.IOException;
import java.sql.Connection;

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

import com.bee.dao.UserDao;
import com.bee.model.PageBean;
import com.bee.utils.DBUtil;
import com.bee.utils.JsonUtil;
import com.bee.utils.ResponseUtil;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class UserListServlet extends HttpServlet {

  private static final long serialVersionUID = 1L;

  DBUtil dbUtil = new DBUtil();
  UserDao userDao = new UserDao();

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

  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    String page = request.getParameter("page");
    String rows = request.getParameter("rows");

    String searchKey = request.getParameter("searchVal");
    System.out.println("查找：" + searchKey);

    PageBean pageBean = new PageBean(Integer.parseInt(page), Integer.parseInt(rows));

    Connection con = null;
    try {
      con = dbUtil.getConnection();
      JSONObject result = new JSONObject();
      JSONArray jsonArray = null;
      int total = 0;
      if (searchKey != null) {
        jsonArray = JsonUtil.formatRsToJsonArray(userDao.userList(con, pageBean, searchKey));
        total = userDao.userCount(con, searchKey);
      } else {
        jsonArray = JsonUtil.formatRsToJsonArray(userDao.userList(con, pageBean));
        total = userDao.userCount(con);
      }
      result.put("rows", jsonArray);
      result.put("total", total);
      ResponseUtil.write(response, result); //返回JSON
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      try {
        dbUtil.closeConnection(con);
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }
}

2. 根据模版导出Excel

  • 思路
    先自定义一个Excel模版文件，并把格式等等设定好。然后利用POI以文件流的方式打开预先定义的Excel模版文件——注意不是使用 Workbook wb = new HSSFWorkbook(); 来新建Excel。 最后把数据写入Excel模版文件并返回前端即可。
  • 修改导出Excel的工具类

public class ExcelUtil {
  ......
  public static Workbook fillExcelData(ResultSet rs, String templateFileName) throws Exception {
    InputStream is = ExcelUtil.class.getResourceAsStream("/com/bee/template/" + templateFileName);
    POIFSFileSystem pfs = new POIFSFileSystem(is);
    Workbook wb = new HSSFWorkbook(pfs);
    Sheet sheet = wb.getSheetAt(0); // 取得第一个sheet
    int cellNums = sheet.getRow(0).getLastCellNum(); // 获取列数（getRow(0)是第一行）
    int rowIndex = 1; // 第二行开始
    while (rs.next()) {
      Row row = sheet.createRow(rowIndex++);
      for (int i = 0; i < cellNums; i++) {
        row.createCell(i).setCellValue(rs.getObject(i + 1).toString());
      }
    }
    return wb;
  }
}

  • 修改导出处理的Servlet

public class ExportExcelServlet extends HttpServlet {
  ......
  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    request.setCharacterEncoding("utf-8"); // 设定编码
    String searchKey = request.getParameter("searchKey");

    Connection con = null;
    try {
      con = dbUtil.getConnection();
      ResultSet rs = null;
      if (searchKey != null) {
        // HTTP GET的URL参数默认是ISO-8859-1编码
        searchKey = new String(searchKey.getBytes("ISO-8859-1"), "UTF-8");
        System.out.println("导出结果：" + searchKey);
        rs = userDao.exportExcel(con, searchKey);
      } else {
        rs = userDao.exportExcel(con);
      }
      Workbook wb = ExcelUtil.fillExcelData(rs, "template.xls");
      ResponseUtil.export(response, wb, searchKey != null ? "导出搜索结果（" + searchKey + "）.xls" : "导出全量.xls");
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      try {
        dbUtil.closeConnection(con);
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }
}


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