Java web+MySQL编写简易候选人投票（完整代码）
代码实现效果，自己选的图片太大了，没有做更改，将就看就行
项目用到的三个jar包自己导入就行
代码结构如下图
Candidate中的代码
public class Candidate {
private int id;
private String name;
private String photoUrl;
private int votes;
public int getId(){
return id;
}
public void setId(int id){
this.id = id;
}
public String getName(){
return name;
}
public void setName(String name){
this.name = name;
}
public String getPhotoUrl(){
return photoUrl;
}
public void setPhotoUrl(String photoUrl){
this.photoUrl = photoUrl;
}
public int getVotes(){
return votes;
}
public void setVotes(int votes){
this.votes = votes;
}
}
AddCandidatePageServlet
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet("/admin/addcan")
public class AddCandidatePageServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType("text/html;charset=utf8");
PrintWriter pw = resp.getWriter();
pw.println("<html><head><title>添加候选人</title></head>");
pw.println("<body>");
pw.println("<form action='add' method = 'POST' enctype='multipart/form-data'>");
pw.println("名字: <input type='text' name='username'><br>");
pw.println("照片:<input type='file' name = 'img'><br>");
pw.println("<input type='submit' value = '提交'>");
pw.println("</form>");
pw.println("</body></html>");
}
}
AddCandidateServlet
@WebServlet("/admin/add")
public class AddCandidateServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//判断上传的文件是否以多段数据进行提交的
if (ServletFileUpload.isMultipartContent(req)) {
//创建FileItemFactory工厂类的示例
FileItemFactory diskFileItemFactory = new DiskFileItemFactory();
//创建解析数据所使用的工具类：ServletFileUpload
ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);
//获取文件存储的绝对路径
String path = getServletConfig().getServletContext().getRealPath("/")+ "photos\\";
//解析数据
try {
String username = null;
String img = null;
List<FileItem> list = servletFileUpload.parseRequest(req);
for (FileItem fileItem : list) {
if (fileItem.isFormField()) {
username = fileItem.getString("UTF-8");
} else {
//获取图片的名字
img = fileItem.getName();
//将文件写入指定的文件夹之中
fileItem.write(new File(path + img));
}
}
//将文件名存入数据库
Candidate candidate = new Candidate();
candidate.setName(username);
candidate.setPhotoUrl(img);
CandidateDao candidateDao = new CandidateDao();
candidateDao.add(candidate);
System.out.println("存入成功");
} catch (Exception e) {
e.printStackTrace();
}
}
resp.sendRedirect("manage");
}
}
DeleteCandidateServlet
@WebServlet("/admin/delete")
public class DeleteCandidateServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
String id = req.getParameter("id");
Candidate candidate=new Candidate();
CandidateDao candidateDao=new CandidateDao();
candidateDao.delete( Integer.parseInt(id));
resp.sendRedirect("manage");
}
}
ManageCandidateServlet
@WebServlet("/admin/manage")
public class ManageCandidateServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setCharacterEncoding("utf-8");
resp.setContentType("text/html;utf-8");
// 获取数据
CandidateDao candidateDao=new CandidateDao();
ArrayList<Candidate> candidates= (ArrayList<Candidate>) candidateDao.candidateList();
// 获取笔
PrintWriter pw=resp.getWriter();
// 编号
int count=1;
pw.print("<!DOCTYPE html><html><head> <meta charset='UTF-8'><title>管理列表</title></head><body>");
pw.print("<div><a href='http://localhost:8080/exercise2_vote_war_exploded/admin/addcan'>添加新用户</a></div>");
pw.print("<table border='1'>");
pw.print("<tr><td>排名</td> <td>名字</td> <td>ID</td> <td>照片</td><td>票数</td><td>修改</td><td>删除</td></tr>");
if (candidates!=null){
for (Candidate person:candidates){
pw.print("<tr>");
pw.print("<td>"+count+"</td>");
pw.print("<td>"+person.getName()+"</td>");
pw.print("<td>"+person.getId()+"</td>");
pw.print("<td><img src='http://localhost:8080/exercise2_vote_war_exploded/photos/"+person.getPhotoUrl()+"'></td>");
pw.print("<td>"+person.getVotes()+"</td>");
pw.print("<td><a href='http://localhost:8080/exercise2_vote_war_exploded/admin/modify?id="+person.getId()+"'>修改</a></td>");
pw.print("<td><a href='http://localhost:8080/exercise2_vote_war_exploded/admin/delete?id="+person.getId()+"'>删除</a></td>");
pw.print("</tr>");
count++;
}
}
pw.print("</table>");
pw.print("<a href='http://localhost:8080/exercise2_vote_war_exploded/index'>用户列表</a>");
pw.print("</body></html>");
}
}
ModifyCandidatePageServlet
@WebServlet("/admin/modify")
public class ModifyCandidatePageServlet extends HttpServlet {
// 修改候选人信息
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType("text/html;utf-8");
resp.setCharacterEncoding("utf-8");
//获取初始候选人数据
String id1= req.getParameter("id");
int id=Integer.parseInt(id1);
CandidateDao candidateDao=new CandidateDao();
Candidate candidate= candidateDao.select(id);
// 渲染成表单数据
PrintWriter pw=resp.getWriter();
pw.print("<!DOCTYPE html><html><head> <meta charset='UTF-8'><title>修改候选人信息</title></head><body>");
pw.print("<form action = 'mod' method = 'POST' enctype='multipart/form-data'>");
pw.print("id : <input type='text' name='id' value='"+candidate.getId()+"'></br>");
pw.print("name : <input type='text' name='username' value='"+candidate.getName()+"'></br>");
pw.print("photo : <input type='file' name='photo' value='"+candidate.getPhotoUrl()+"'></br>");
pw.print("<input type='submit' value='提交'></br>");
pw.print("</form>");
pw.print("</body></html>");
}
}
ModifyCandidateServlet
@WebServlet("/admin/mod")
public class ModifyCandidateServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
if (ServletFileUpload.isMultipartContent(req)) {
System.out.println("qwertyy");
//创建FileItemFactory工厂类的示例
FileItemFactory diskFileItemFactory = new DiskFileItemFactory();
//创建解析数据所使用的工具类：ServletFileUpload
ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);
//
String path = getServletConfig().getServletContext().getRealPath("/") + "photos\\";
//解析数据
try {
String username = null;
String img = null;
String id = null;
List<FileItem> list = servletFileUpload.parseRequest(req);
for (FileItem fileItem : list) {
System.out.println(fileItem);
if (fileItem.isFormField()) {
if ("username".equals(fileItem.getFieldName())){
username = fileItem.getString("UTF-8");
System.out.println(username+"获取用户姓名");
}
if ("id".equals(fileItem.getFieldName())){
System.out.println("id的获取"+fileItem.getString());
id = fileItem.getString("UTF-8");
}
}
else {
//获取图片的名字
img = fileItem.getName();
// id=req.getParameter("id");
//将文件写入指定文件夹之中
fileItem.write(new File(path + img));
}
}
//将文件名存入数据库
Candidate candidate= new Candidate();
candidate.setName(username);
candidate.setPhotoUrl(img);
candidate.setId(Integer.parseInt(id));
CandidateDao candidateDao=new CandidateDao();
candidateDao.update(candidate);
System.out.println("更新成功");
} catch (Exception e) {
e.printStackTrace();
}
resp.sendRedirect("manage");
}else{
System.out.println("错误！");
}
}
}
ListCandidateServlet
@WebServlet("/index")
public class ListCandidateServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//先获取数据
CandidateDao candidateDao=new CandidateDao();
ArrayList<Candidate> candidates= (ArrayList<Candidate>) candidateDao.candidateList();
// 排名编号 ---查询到的数据以投票数降序排序
int count=1;
resp.setCharacterEncoding("utf-8");
resp.setContentType("text/html;utf-8");
PrintWriter printWriter=resp.getWriter();
printWriter.print("<!DOCTYPE html><html><head> <meta charset='UTF-8'><title>简易投票系统</title></head><body>");
printWriter.print("<table border='1'>");
printWriter.print("<tr> <td>排名</td> <td>名字</td> <td>ID</td> <td>照片</td><td>票数</td><td>投票</td></tr>");
if (candidates!=null){
for (Candidate person:candidates){
printWriter.print("<tr>");
printWriter.println("<td>" + count + "</td>");
printWriter.println("<td>" + person.getName() + "</td>");
printWriter.println("<td>" + person.getId() + "</td>");
//待修改
printWriter.println("<td><img src='photos/" + person.getPhotoUrl() + "'></td>");
printWriter.println("<td>" + person.getVotes() + "</td>");
printWriter.println("<td><a href = '/exercise2_vote_war_exploded/vote?id="+ person.getId()+ "'>投票</a></td>");
printWriter.println("</tr>");
count++;
}
}
printWriter.println("</table>");
printWriter.println("<a href='http://localhost:8080/exercise2_vote_war_exploded/admin/manage'>管理候选人</a>");
printWriter.println("</body></html>");
}
}
VoteServlet
@WebServlet("/vote")
public class VoteServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
String id1=req.getParameter("id");
if (id1!=null){
System.out.println(id1);
int id=Integer.parseInt(id1);
CandidateDao candidateDao=new CandidateDao();
candidateDao.addVote(id);
req.getRequestDispatcher("index").forward(req,resp);
}
System.out.println("未获取到id");
}
}
dao层里面的CandidateDao
public class CandidateDao implements Dao {
Connection connection;
{
try{
connection = JdbcUtil.getConnection();
} catch (SQLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public void add(Candidate candidate) {
String sql="insert into table_candidate values(null,?,?,?)";
try(PreparedStatement ps=connection.prepareStatement(sql)){
ps.setString(1,candidate.getName());
ps.setString(2,candidate.getPhotoUrl());
ps.setInt(3,candidate.getVotes());
ps.execute();
System.out.println("向数据库中插入一条记录");
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public void update(Candidate candidate) {
String sql="update table_candidate set name= ?,photoUrl = ? where id=?";
try(PreparedStatement ps=connection.prepareStatement(sql)){
ps.setInt(3,candidate.getId());
ps.setString(1,candidate.getName());
ps.setString(2,candidate.getPhotoUrl());
//ps.setInt(3,candidate.getVotes());
ps.execute();
System.out.println("更新了数据库中这条id为："+candidate.getId()+"的记录");
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public void delete(int id) {
String sql="delete from table_candidate where id=?";
try (PreparedStatement ps=connection.prepareStatement(sql);){
ps.setInt(1,id);
ps.execute();
System.out.println("删除了数据库中这条id为："+id+"的记录");
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public Candidate select(int id) {
Candidate candidate=null;
String sql=" select * from table_candidate where id= ?";
try( PreparedStatement ps=connection.prepareStatement(sql);) {
ps.setInt(1,id);
ResultSet rs= ps.executeQuery();
if (rs.next()){
String name=rs.getString(2);
String photoUrl=rs.getString(3);
int votes=rs.getInt(4);
candidate=new Candidate();
candidate.setId(id);
candidate.setName(name);
candidate.setPhotoUrl(photoUrl);
candidate.setVotes(votes);
System.out.println("查询单条记录成功");
}
} catch (SQLException e) {
e.printStackTrace();
}
return candidate;
}
@Override
public List<Candidate> candidateList() {
// 直接调用有参获取候选人方法，只不过参数是0-最后
return orderPageList(0,10000);
}
@Override
public List<Candidate> orderPageList(int start, int count) {
// 存放获取候选人列表
ArrayList<Candidate> candidates=new ArrayList<Candidate>();
String sql="select * from table_candidate order by votes desc limit ? , ? ";
try (PreparedStatement ps=connection.prepareStatement(sql);) {
ps.setInt(1,start);
ps.setInt(2,count);
ResultSet rs=ps.executeQuery();
while (rs.next()){
Candidate candidate=new Candidate();
int id=rs.getInt(1);
String name=rs.getString(2);
String photoUrl=rs.getString(3);
int votes=rs.getInt(4);
candidate.setId(id);
candidate.setName(name);
candidate.setPhotoUrl(photoUrl);
candidate.setVotes(votes);
candidates.add(candidate);
// System.out.println("查询候选人信息成功");
}
} catch (SQLException e) {
e.printStackTrace();
}
return candidates;
}
public void addVote(int id){
String sql="update table_candidate set votes=votes+1 where id=?";
try ( PreparedStatement ps=connection.prepareStatement(sql);){
ps.setInt(1,id);
ps.execute();
// System.out.println("id为："+id+"的候选者投票数加一");
} catch (SQLException e) {
e.printStackTrace();
}
}
}
Dao
public interface Dao {
public void add(Candidate candidate);
public void update(Candidate candidate);
public void delete (int id);
//获取单个候选人
public Candidate select(int id);
//候选人列表
public List<Candidate> candidateList();
//分页查询候选人
public List<Candidate> orderPageList(int start,int count);
}
JdbcUti
public class JdbcUtil {
private static Connection connection;
public static Connection getConnection() throws ClassNotFoundException, SQLException{
Class.forName("com.mysql.cj.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC", "root", "自己数据的密码");
return connection;
}
//关闭连接
public static void closeResourse(Connection connection, PreparedStatement preparedStatement){
if(preparedStatement!=null){
try{
preparedStatement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (connection!=null){
try{
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public static void closeResourse(Connection connection, PreparedStatement preparedStatement, ResultSet rs){
if(preparedStatement!=null){
try{
preparedStatement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(connection !=null){
try{
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (rs!=null){
try{
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}