• 在java中导出excel


    package com.huawei.controller;

    import java.io.File;
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;

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

    import org.apache.commons.fileupload.FileItem;
    import org.apache.commons.fileupload.FileUploadException;
    import org.apache.commons.fileupload.disk.DiskFileItemFactory;
    import org.apache.commons.fileupload.servlet.ServletFileUpload;
    import org.apache.poi.ss.usermodel.Workbook;

    import com.huawei.common.Page;
    import com.huawei.po.Users;
    import com.huawei.service.UsersService;

    /**
    * Servlet implementation class UsersController
    */
    public class UsersController extends HttpServlet {
    private static final long serialVersionUID = 1L;

    private UsersService usersService = new UsersService();

    /**
    * @see HttpServlet#HttpServlet()
    */
    public UsersController() {
    super();
    // TODO Auto-generated constructor stub
    }

    /**
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    this.doPost(request, response);
    }

    /**
    * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    /**
    * 将 当前的doPost方法 当作中专站
    */
    String _method = request.getParameter("_method");

    if("findAll".equalsIgnoreCase(_method)){
    this.findAll(request, response);
    }else if("deleteById".equalsIgnoreCase(_method)){
    this.deleteById(request, response);
    }else if("register".equalsIgnoreCase(_method)){
    this.register(request, response);
    }else if("findById".equalsIgnoreCase(_method)){
    this.findById(request, response);
    }else if("update".equalsIgnoreCase(_method)){
    this.update(request, response);
    }else if("analyzeAge".equalsIgnoreCase(_method)){
    this.analyzeAge(request, response);
    }else if("exportExcel".equalsIgnoreCase(_method)){
    this.exportExcel(request, response);
    }
    }

    /**
    *
    * 当从前台提交一个请求过来的时候 应该去后台数据库将数据查询出来 动态的生成WorkBook
    *
    * 直接将WorkBook的输出流定向到 response的输出流中去
    *
    *
    * @param request
    * @param response
    * @throws ServletException
    * @throws IOException
    */

    private void exportExcel(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
    response.setHeader("Content-Disposition", "attachment;filename="users.xls"");
    //response.getOutputStream();
    Workbook wb =this.usersService.exportExcel();
    wb.write(response.getOutputStream());
    wb.close();
    }

    private void analyzeAge(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
    // TODO Auto-generated method stub
    response.getWriter().write(this.usersService.analyzeAge());

    }

    private void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{

    Users curr = (Users) request.getSession().getAttribute("admin");



    if(ServletFileUpload.isMultipartContent(request)){
    Map<String, FileItem> map = new HashMap<String, FileItem>();
    //创建工厂
    DiskFileItemFactory factory = new DiskFileItemFactory();
    //得到JVM提供的缓存目录
    ServletContext context = this.getServletContext();
    File repository = (File)context.getAttribute("javax.servlet.context.tempdir");
    factory.setRepository(repository);
    //创建ServletFileUpload
    ServletFileUpload upload = new ServletFileUpload(factory);

    //解析请求
    try {
    List<FileItem> items = upload.parseRequest(request);
    //users = new Users();

    for(FileItem item:items){
    //form表单里面的每一个字段
    map.put(item.getFieldName(), item);
    }


    Users u = new Users();

    u.setId(Integer.parseInt(map.get("id").getString()));
    u.setUsername(map.get("username").getString());
    u.setPassword(map.get("password").getString());
    u.setEmail(map.get("email").getString());
    //u.setImage(Integer.parseInt(map.get("id").getString()));
    u.setAge(Integer.parseInt(map.get("age").getString()));





    //处理 前一步的数据没有顺序的问题
    //for(String key:map.keySet()){
    //FileItem item = map.get(key);

    //if(item.isFormField()){

    //没有顺序

    //}else{
    //得到跟路径
    String path = context.getRealPath("/");
    //得到附件目录
    File attachment = new File(path,"attachment/"+map.get("username").getString());
    //如果没有 就创建目录
    System.out.println(attachment.getAbsolutePath());
    System.out.println(attachment.exists());
    if(!attachment.exists()){
    attachment.mkdirs();
    }

    FileItem image = map.get("image");

    File output = new File(attachment,System.currentTimeMillis()+"."+getSuffix(image.getName()));

    image.write(output);
    u.setImage("attachment/"+map.get("username").getString()+"/"+output.getName());
    //System.currentTimeMillis()
    this.usersService.update(u);
    this.findAll(request, response);
    //}
    //}
    //map.get("id");
    } catch (Exception e) {
    e.printStackTrace();
    }
    }


    }

    private String getSuffix(String name){
    if(name!=null){
    String[] suffixs = name.split("\.");
    if(suffixs.length>1){
    return suffixs[suffixs.length-1];
    }
    }
    return "";
    }

    private void findById(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
    String id = request.getParameter("id");
    if(id!=null && id.trim()!=""){
    Users users = this.usersService.findById(Integer.parseInt(id));
    request.setAttribute("users", users);
    request.getRequestDispatcher("/views/update.jsp").forward(request, response);
    return ;
    }
    }

    private void register(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    Users users = null;
    //判断是否有文件上传
    if(ServletFileUpload.isMultipartContent(request)){
    //创建工厂
    DiskFileItemFactory factory = new DiskFileItemFactory();
    //得到JVM提供的缓存目录
    ServletContext context = this.getServletContext();
    File repository = (File)context.getAttribute("javax.servlet.context.tempdir");
    factory.setRepository(repository);
    //创建ServletFileUpload
    ServletFileUpload upload = new ServletFileUpload(factory);

    //解析请求
    try {
    List<FileItem> items = upload.parseRequest(request);
    users = new Users();

    for(FileItem item:items){
    //form表单里面的每一个字段

    }
    //得到跟路径
    String path = context.getRealPath("/");
    //得到附件目录
    File attachment = new File(path,"attachment");
    //如果没有 就创建目录
    if(!attachment.exists()){
    attachment.mkdirs();
    }


    } catch (FileUploadException e) {
    e.printStackTrace();
    }
    }

    }

    protected void deleteById(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    String id = request.getParameter("id");
    this.usersService.deleteById(Integer.parseInt(id));
    response.sendRedirect("usersController?_method=findAll");

    }

    protected void findAll(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //List<Users> users = this.usersService.findAll();
    //request.setAttribute("users", users);

    String keyword = request.getParameter("keyword");

    if(keyword==null){
    keyword = "";
    }

    Page page = new Page();
    String curr = request.getParameter("curr");
    if(curr ==null || curr.trim().equals("")){
    curr ="1";
    }
    page.getKeywords().put("username", keyword);
    page.setCurr(Integer.parseInt(curr));
    page = this.usersService.find4Page(page);
    request.setAttribute("page", page);
    request.getRequestDispatcher("/views/index.jsp").forward(request, response);
    return;
    }

    }

    package com.huawei.service;

    import java.lang.reflect.Field;
    import java.lang.reflect.Method;
    import java.util.Date;
    import java.util.List;
    import java.util.regex.Pattern;

    import org.apache.poi.hssf.usermodel.HSSFWorkbook;
    import org.apache.poi.ss.usermodel.Cell;
    import org.apache.poi.ss.usermodel.CellStyle;
    import org.apache.poi.ss.usermodel.Row;
    import org.apache.poi.ss.usermodel.Sheet;
    import org.apache.poi.ss.usermodel.Workbook;
    import org.apache.poi.ss.util.CellRangeAddress;

    import com.huawei.common.Page;
    import com.huawei.dao.UsersDAO;
    import com.huawei.po.Users;
    import com.huawei.utils.BeanUtil;

    public class UsersService {

    private UsersDAO usersDAO = new UsersDAO();

    public List<Users> findAll(){
    return this.usersDAO.findAll();
    }

    public void deleteById(Integer id) {
    // TODO Auto-generated method stub
    this.usersDAO.delete(id);
    }

    public Page find4Page(Page page){
    return this.usersDAO.find4Page(page);
    }

    public Users findByUsername(String username) {
    List<Users> users = this.usersDAO.findBy("username",username);
    return users.size()>0?users.get(0):null;
    }

    public Users findById(Integer id){
    return this.usersDAO.findById(id);
    }

    public void update(Users users){
    this.usersDAO.update(users);
    }

    public String analyzeAge(){
    return this.usersDAO.analyzeAge();
    }

    public Workbook exportExcel(){
    //创建一个工作薄
    Workbook wb = new HSSFWorkbook();

    List<Users> users = this.findAll();
    //用户生成excel的列数
    Field []fields = Users.class.getDeclaredFields();

    Sheet sheet = wb.createSheet("用户信息");
    Row title = sheet.createRow(0);
    //设置样式
    CellStyle cellStyle = wb.createCellStyle();
    //设置字体的对其方式
    cellStyle.setAlignment(CellStyle.ALIGN_CENTER);
    cellStyle.setVerticalAlignment(CellStyle.VERTICAL_CENTER);

    Cell tCell = title.createCell(0);
    tCell.setCellValue("用户信息列表");
    tCell.setCellStyle(cellStyle);
    //合并单元格
    sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, fields.length-1));

    Row header = sheet.createRow(1);

    for(int i=0;i<fields.length;i++){
    Cell cell = header.createCell(i);
    //将属性的名字 当作表头
    cell.setCellValue(fields[i].getName());
    }

    for(int i=0;i<users.size();i++){
    Row row = sheet.createRow(i+2);
    for(int j=0;j<fields.length;j++){
    Cell cell = row.createCell(j);
    try{
    Method method = Users.class.getDeclaredMethod(BeanUtil.getter(fields[j]));
    Object value = method.invoke(users.get(i));

    if(value!=null){
    if(value instanceof Date){

    }else if(value instanceof Number){
    cell.setCellValue(Double.parseDouble(value+""));
    }else if(value instanceof String){
    if(Pattern.matches("^\d+(\.\d+)?$", value+"")){
    cell.setCellValue(Double.parseDouble(value+""));
    }else{
    cell.setCellValue(value+"");
    }
    }
    }else{
    cell.setCellValue("");
    }

    /*if(value==null){
    cell.setCellValue("");
    }else{
    cell.setCellValue(value.toString());
    }*/

    //cell.setcellva

    }catch (Exception e) {
    e.printStackTrace();
    }
    }
    }

    return wb;
    }
    }

    package com.huawei.dao;

    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.List;

    import com.huawei.base.BaseDAO;
    import com.huawei.common.CallBack;
    import com.huawei.common.Page;
    import com.huawei.po.Users;
    import com.huawei.utils.BeanUtil;

    public class UsersDAO extends BaseDAO<Users, Integer>{

    @Override
    public Page find4Page(Page page) {
    //构建sql语句
    String sql = "SELECT * FROM "+BeanUtil.getTableName(clazz)+" WHERE username LIKE ? LIMIT ?,?";
    String count = "SELECT COUNT(1) FROM "+BeanUtil.getTableName(clazz)+" WHERE username LIKE ?";
    //得到数据
    List<Users> data = this.find(sql, new Object[]{"%"+page.getKeywords().get("username")+"%",(page.getCurr()-1)*page.getPageSize(),page.getPageSize()});
    page.setRowCount(this.getCount(count,new Object[]{"%"+page.getKeywords().get("username")+"%"}));
    page.setData(data);
    return page;
    }

    public String analyzeAge(){

    final StringBuilder sb = new StringBuilder("[");

    String sql = "SELECT "+
    "CASE "+
    "WHEN age>0 && age<11 THEN '十岁以下' "+
    "WHEN age>10 && age<21 THEN '11-20' "+
    "WHEN age>20 && age<31 THEN '21-30' "+
    "WHEN age>30 && age<41 THEN '31-40' "+
    "WHEN age>40 && age<51 THEN '41-50' "+
    "WHEN age>50 && age<61 THEN '51-60' "+
    "WHEN age>60 && age<71 THEN '61-70' "+
    "WHEN age>70 && age<81 THEN '71-80' "+
    "WHEN age>80 && age<91 THEN '81-90' "+
    "WHEN age>90 && age<101 THEN '91-100' "+
    "WHEN age>100 THEN '一百岁以上' "+
    "END as 'label',count(age) as 'value' "+
    "FROM "+
    "users "+
    "GROUP BY label ";

    this.executeQuery(sql, null, new CallBack() {

    @Override
    public void execute(ResultSet rs) throws SQLException {
    //处理数据
    //"{"name":"","value":""}"
    while(rs.next()){
    sb.append("{").append(""name":"").append(rs.getString("label")+"","value":"").append(rs.getInt("value")+""").append("},");
    }
    }
    });

    if(sb.length()>1){
    sb.deleteCharAt(sb.length()-1);
    }

    sb.append("]");
    return sb.toString();
    }

    }

    package com.huawei.base;

    import java.io.Serializable;
    import java.lang.reflect.Array;
    import java.lang.reflect.Field;
    import java.lang.reflect.Method;
    import java.lang.reflect.ParameterizedType;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.ResultSetMetaData;
    import java.sql.SQLException;
    import java.util.ArrayList;
    import java.util.List;

    import com.huawei.common.CallBack;
    import com.huawei.common.Page;
    import com.huawei.utils.BeanUtil;
    import com.huawei.utils.DBUtil;

    /**
    * @author Administrator
    *
    *
    * void executeQuery(String sql,Object[] parmas,CallBack callback) 通用的查询
    * void executeUpdate(String sql,Object[] parmas) //通用的执行
    *
    * List<Object> findAll() //查询全部
    * Object findOne(Integer id) //根据id查询一个
    *
    * void save(Object o) //给定一个对象 然后存储到数据库
    *
    * void update(Object o) //根据一个对象 更新数据库中所对应的字段
    *
    * void delete(Object o) //根据一个对象删除数据库中 对应的记录
    * void deleteById(Integer id) //根据传入的id删除
    * void delete(String sql,Object[] params) //自定义删除
    *
    *
    *
    *
    */
    public abstract class BaseDAO<T,ID extends Serializable> {


    //目标类 用于 反射
    protected Class<T> clazz;

    @SuppressWarnings("unchecked")
    public BaseDAO() {
    ParameterizedType type = (ParameterizedType) this.getClass().getGenericSuperclass();
    //得到类上面的泛型参数的实际类型
    clazz = (Class<T>) type.getActualTypeArguments()[0];
    }

    /**
    * 通用的查寻方法
    * @param sql 给定一个sql语句
    * @param params 给定与sql语句中相对应的参数
    * @param callBack 用于处理结果集的回调函数
    */
    public void executeQuery(String sql,Object []params,CallBack callBack){

    Connection connection = DBUtil.getConnection();

    PreparedStatement ps = null;
    ResultSet rs = null;
    try {
    ps = connection.prepareStatement(sql);
    //处理参数
    if(params!=null && params.length>0){
    for(int i=0;i<params.length;i++){
    ps.setObject(i+1, params[i]);
    }
    }
    System.out.println("ORM:"+sql);
    rs = ps.executeQuery();
    //处理业务逻辑
    callBack.execute(rs);

    } catch (SQLException e) {
    e.printStackTrace();
    }finally{
    DBUtil.close(rs,ps,connection);
    }

    }

    /**
    * 除了查询以外 的所有操作
    * @param sql 给定一个sql语句
    * @param params 参数
    */
    public void executeUpdate(String sql,Object []params){
    Connection connection = DBUtil.getConnection();
    PreparedStatement ps = null;
    try {
    ps = connection.prepareStatement(sql);
    //处理参数
    if(params!=null && params.length>0){
    for(int i=0;i<params.length;i++){
    ps.setObject(i+1, params[i]);
    }
    }
    System.out.println("ORM:"+sql);
    ps.executeUpdate();
    } catch (SQLException e) {
    e.printStackTrace();
    }finally{
    DBUtil.close(ps,connection);
    }
    }

    /**
    * 通用查询
    * @param sql
    * @param params
    * @return
    */
    public List<T> find(String sql,Object []params){

    final List<T> result = new ArrayList<T>();
    this.executeQuery(sql, params, new CallBack() {

    @Override
    public void execute(ResultSet rs) throws SQLException {
    //处理结果
    try {
    //得到虚拟表的 结构信息
    ResultSetMetaData rsmd = rs.getMetaData();
    while(rs.next()){
    //每一行代表一个对象
    T o = clazz.newInstance();
    //每一个单元格 代表对象中的一个属性
    for(int i=0;i<rsmd.getColumnCount();i++){
    //得到列明
    String column_name = rsmd.getColumnName(i+1);
    //根据列名去得到 clazz中的 属性
    Field field = clazz.getDeclaredField(column_name);
    //得到 set方法 setUsername(String name)
    Method method = clazz.getDeclaredMethod(BeanUtil.setter(field), field.getType());
    method.invoke(o, rs.getObject(column_name));
    }
    result.add(o);
    }
    } catch (Exception e) {
    e.printStackTrace();
    }
    }
    });
    return result;
    }

    /**
    * 查找全部
    * @return 返回一个结果集
    */
    public List<T> findAll(){
    //存储结果集
    String sql = "SELECT * FROM "+BeanUtil.getTableName(clazz);
    return this.find(sql, null);
    }

    public T findById(ID id){
    String sql = "SELECT * FROM "+BeanUtil.getTableName(clazz) +" WHERE id=?";
    List<T> result = this.find(sql, new Object[]{id});
    return result.size()>0?result.get(0):null;
    }

    public List<T> findBy(String prop,Object param){
    String sql = "SELECT * FROM "+BeanUtil.getTableName(clazz) +" WHERE "+prop+"=?";
    return this.find(sql, new Object[]{param});
    }

    public Page find4Page(Page page){
    //构建sql语句
    String sql = "SELECT * FROM "+BeanUtil.getTableName(clazz)+" LIMIT ?,?";
    //得到数据
    List<T> data = this.find(sql, new Object[]{(page.getCurr()-1)*page.getPageSize(),page.getPageSize()});
    page.setRowCount(this.getCount());
    page.setData(data);
    return page;

    }

    public Long getCount(){
    String sql = "SELECT COUNT(1) FROM "+BeanUtil.getTableName(clazz);
    return this.getCount(sql, null);

    }
    public Long getCount(String sql,Object[] params){

    final long []count = new long[]{0L};

    this.executeQuery(sql, params, new CallBack() {

    @Override
    public void execute(ResultSet rs) throws SQLException {
    while(rs.next()){
    count[0] = rs.getLong(1);
    }

    }
    });

    return count[0];
    }

    /**
    * 将给定的对象 持久化到数据库
    * @param o 被持久化对象
    */
    public void save(T o){
    StringBuilder sb = new StringBuilder("INSERT INTO "+BeanUtil.getTableName(clazz)+" (");
    StringBuilder values = new StringBuilder(" VALUES (");
    //存储参数
    List<Object> params = new ArrayList<Object>();
    //得到所有的属性
    Field []fields = clazz.getDeclaredFields();
    try{
    for(Field field:fields){
    sb.append(BeanUtil.getColumnName(field)).append(",");
    values.append("?,");
    Method method = clazz.getDeclaredMethod(BeanUtil.getter(field));
    //得到属性的值
    params.add(method.invoke(o));
    }
    }catch (Exception e) {
    e.printStackTrace();
    }
    //处理sql语句
    sb.deleteCharAt(sb.length()-1).append(")");
    values.deleteCharAt(values.length()-1).append(")");
    sb.append(values);
    this.executeUpdate(sb.toString(), params.toArray());
    }



    /**
    * 更新 更新的对象中 一定要包含id
    * @param o
    */
    public void update(T o){
    StringBuilder sb = new StringBuilder("UPDATE "+BeanUtil.getTableName(clazz)+" SET ");
    //存储参数
    List<Object> params = new ArrayList<Object>();
    //得到所有的属性
    Field []fields = clazz.getDeclaredFields();

    Object id = null;

    try{
    for(Field field:fields){
    //UPDATE USERS SET USERNAME=?,PASSWORD=?
    String name = BeanUtil.getColumnName(field);
    Method method = clazz.getDeclaredMethod(BeanUtil.getter(field));
    //得到属性的值

    Object value = method.invoke(o);

    if("id".equals(name)){
    id = value;
    continue;
    }
    sb.append(name+"=?").append(",");
    params.add(value);
    }
    }catch (Exception e) {
    e.printStackTrace();
    }
    //处理sql语句
    sb.deleteCharAt(sb.length()-1).append(" WHERE id=?");
    if(id==null){
    System.out.println("ID不能为空");
    return;
    }
    params.add(id);
    this.executeUpdate(sb.toString(), params.toArray());

    }

    @SuppressWarnings("unchecked")
    public void delete(ID id){
    //动态创建泛型数组
    ID []ids = (ID[])Array.newInstance(id.getClass(), 1);
    ids[0] =id;
    this.delete(ids);
    }

    @SuppressWarnings("unchecked")
    public void delete(T o){
    try {
    ID id = (ID)this.clazz.getDeclaredMethod("getId").invoke(o);
    if(id!=null){
    this.delete(id);
    return ;
    }
    System.out.println("ID不能为空");
    } catch (Exception e) {
    e.printStackTrace();
    }
    }
    public void delete(ID[] ids){
    String sql = "DELETE FROM "+BeanUtil.getTableName(clazz) + " WHERE id in (?)";
    this.executeUpdate(sql, ids);
    }

    public void delete(String sql,Object[] params){
    this.executeUpdate(sql, params);
    }
    }

    package com.huawei.utils;

    import java.lang.reflect.Field;

    /**
    * bean 工具
    * @author Administrator
    *
    */
    public class BeanUtil {

    /**
    * 获取set方法名
    * 获取标名
    * @param clazz
    */
    public static String getTableName(Class<?> clazz){
    //获取类名
    String name = clazz.getSimpleName();
    name = name.substring(0, 1).toLowerCase()+name.substring(1);
    return name;
    }

    /**
    * @param field
    * @return
    */
    public static String setter(Field field){
    String name = field.getName();
    return "set"+name.substring(0,1).toUpperCase()+name.substring(1);
    }
    public static String getter(Field field){
    return getter(field.getName());
    }
    public static String getter(String name){
    return "get"+name.substring(0,1).toUpperCase()+name.substring(1);
    }

    public static String getColumnName(Field field){
    String name = field.getName();
    return name.substring(0,1).toLowerCase()+name.substring(1);
    }
    }

  • 相关阅读:
    PyQt5对话框
    PyQt5基础控件
    PyQt5主界面
    PyQt5入门
    ioctl太多虚拟内存不够用
    code principles
    Error: watch ENOSPC
    intelJ
    cas
    C的函数指针的作用,以及其赋值是弱类型的
  • 原文地址:https://www.cnblogs.com/hwgok/p/5883441.html
Copyright © 2020-2023  润新知