JAVA:使用IntelliJ IDEA在JSP中显示mysql数据
所以我使用intelliJ和Java作为编程语言已经快两个月了。我正在开发一个web应用程序,我已经成功地使用JAVA:使用IntelliJ IDEA在JSP中显示mysql数据,java,mysql,jsp,servlets,intellij-idea,Java,Mysql,Jsp,Servlets,Intellij Idea,所以我使用intelliJ和Java作为编程语言已经快两个月了。我正在开发一个web应用程序,我已经成功地使用LoginServlet.java实现了一个用户登录。然而,我想在JSP中显示一个COUNT(*)输出,但是我在如何显示数据输出方面遇到了一些问题。我不确定servlet是否允许多个请求.getRequestDispatcher,或者我需要在servlet之外编写代码(可能在jsp中)。如果您能提供一些指导,我们将不胜感激 这是我的密码 UserLogin.java Servlet @W
LoginServlet.java
实现了一个用户登录。然而,我想在JSP中显示一个COUNT(*)
输出,但是我在如何显示数据输出方面遇到了一些问题。我不确定servlet是否允许多个请求.getRequestDispatcher
,或者我需要在servlet之外编写代码(可能在jsp中)。如果您能提供一些指导,我们将不胜感激
这是我的密码
UserLogin.java Servlet
@WebServlet("/organizer")
public class UserLogin extends HttpServlet {
@SuppressWarnings("Duplicates")
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try{
String email = request.getParameter("email");
String password = request.getParameter("password");
OrganizerDao e = new OrganizerDao();
HttpSession session = request.getSession();
session.setAttribute("email", email);
Connection con= OrganizerDao.getConnection();
PreparedStatement st=con.prepareStatement("select id, firstname, lastname from users where email=? and password=?");
st.setString(1,email);
st.setString(2,password);
ResultSet rs=st.executeQuery();
if (rs.next()) {
request.setAttribute("id",rs.getInt("id"));
request.setAttribute("firstname",rs.getString("firstname"));
request.setAttribute("lastname",rs.getString("lastname"));
RequestDispatcher rd = request.getRequestDispatcher("dashboard.jsp");
rd.include(request, response);
} else {
out.println("<div class=\"alert alert-danger\" role=\"alert\">");
out.println("<center>Oh snap! Change a few things and try submitting again.</center>");
out.println("</div>");
request.getRequestDispatcher("login.jsp").include(request, response);
}
con.close();
}catch(Exception ex){ex.printStackTrace();}
}
@SuppressWarnings("Duplicates")
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request,response);
getEventsCount(request,response);
getAffiliatesCount(request,response);
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request,response);
getEventsCount(request,response);
getAffiliatesCount(request, response);
}
@SuppressWarnings("Duplicates")
protected void getEventsCount(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
//call ConnectToDatabase
try {
String email = request.getParameter("email");
String password = request.getParameter("password");
HttpSession session = request.getSession();
session.setAttribute("email", email);
try {
String query = "SELECT count(events.userid) AS etotal from events, users where events.userid=users.id and users.email=? and users.password=?";
int count = 0;
Connection connection = EventsDAO.getConnection();
PreparedStatement st = connection.prepareStatement(query);
st.setString(1, email);
st.setString(2, password);
ResultSet rs = st.executeQuery();
while (rs.next()) {
count = rs.getInt("etotal");
request.setAttribute("count", count);
RequestDispatcher rd = request.getRequestDispatcher("dashboard.jsp");
rd.include(request, response);
}
} catch (SQLException e) {
e.printStackTrace();
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
@SuppressWarnings("Duplicates")
protected void getAffiliatesCount(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
//call ConnectToDatabase
try {
String email = request.getParameter("email");
String password = request.getParameter("password");
HttpSession session = request.getSession();
session.setAttribute("email", email);
try {
String query = "SELECT count(affiliates.userid) AS affiliatestotal from affiliates, users where affiliates.userid=users.id and users.email=? and users.password=?";
int affiliatescount = 0;
Connection connection = EventsDAO.getConnection();
PreparedStatement st = connection.prepareStatement(query);
st.setString(1, email);
st.setString(2, password);
ResultSet rs = st.executeQuery();
while (rs.next()){
affiliatescount = rs.getInt("affiliatestotal");
request.setAttribute("affiliatescount",affiliatescount);
RequestDispatcher rd = request.getRequestDispatcher("dashboard.jsp");
rd.include(request, response);
}
} catch (SQLException e) {
e.printStackTrace();
}
}catch(Exception ex){ex.printStackTrace();}
}
}
@SuppressWarnings("Duplicates")
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request,response);
getEventsCount(request,response);
getAffiliatesCount(request,response);
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request,response);
getEventsCount(request,response);
getAffiliatesCount(request, response);
}
更新:我能够通过使用字符串作为所有getDispatcher转发器的占位符来解决数据显示问题。但是错误页面现在不能正确显示。
这是我的密码:
UserLogin.java
String page = "";
@SuppressWarnings("Duplicates")
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
//call ConnectToDatabase
try{
String email = request.getParameter("email");
String password = request.getParameter("password");
OrganizerDao e = new OrganizerDao();
HttpSession session = request.getSession();
session.setAttribute("email", email);
Connection con= OrganizerDao.getConnection();
PreparedStatement st=con.prepareStatement("select id, firstname, lastname from users where email=? and password=?");
st.setString(1,email);
st.setString(2,password);
ResultSet rs=st.executeQuery();
if (rs.next()) {
request.setAttribute("id",rs.getInt("id"));
request.setAttribute("firstname",rs.getString("firstname"));
request.setAttribute("lastname",rs.getString("lastname"));
//RequestDispatcher rd = request.getRequestDispatcher("dashboard.jsp");
//rd.include(request, response);
page = "dashboard.jsp";
} else {
out.println("<div class=\"alert alert-danger\" role=\"alert\">");
out.println("<center>Oh snap! Change a few things and try submitting again.</center>");
out.println("</div>");
//request.getRequestDispatcher("/login.jsp").include(request, response);
page = "/login.jsp";
}
con.close();
}catch(Exception ex){ex.printStackTrace();}
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
//call ConnectToDatabase
processRequest(request,response);
getEventsCount(request,response);
getAffiliatesCount(request,response);
getTotalWithdrawal(request, response);
if(page!=null){
request.getRequestDispatcher("/dashboard.jsp").include(request, response);
}else {
out.println("<div class=\"alert alert-danger\" role=\"alert\">");
out.println("<center>Oh snap! Change a few things and try submitting again.</center>");
out.println("</div>");
request.getRequestDispatcher("/login.jsp").include(request, response);
}
}
String page=”“;
@抑制警告(“重复”)
受保护的void processRequest(HttpServletRequest请求、HttpServletResponse响应)
抛出ServletException、IOException{
setContentType(“text/html;charset=UTF-8”);
PrintWriter out=response.getWriter();
//调用ConnectToDatabase
试一试{
字符串email=request.getParameter(“email”);
字符串密码=request.getParameter(“密码”);
OrganizerDao e=新的OrganizerDao();
HttpSession session=request.getSession();
session.setAttribute(“电子邮件”,电子邮件);
Connection con=OrganizerDao.getConnection();
PreparedStatement st=con.prepareStatement(“从电子邮件=?和密码=?)的用户中选择id、名字和姓氏”);
st.setString(1,电子邮件);
st.setString(2,密码);
结果集rs=st.executeQuery();
如果(rs.next()){
request.setAttribute(“id”,rs.getInt(“id”);
request.setAttribute(“firstname”,rs.getString(“firstname”);
request.setAttribute(“lastname”,rs.getString(“lastname”);
//RequestDispatcher rd=request.getRequestDispatcher(“dashboard.jsp”);
//包括(请求、响应);
page=“dashboard.jsp”;
}否则{
out.println(“”);
println(“哦,突然!更改一些内容,然后再次尝试提交。”);
out.println(“”);
//getRequestDispatcher(“/login.jsp”).include(请求、响应);
page=“/login.jsp”;
}
con.close();
}catch(异常ex){ex.printStackTrace();}
}
受保护的void doPost(HttpServletRequest请求,
HttpServletResponse响应)引发ServletException,IOException{
setContentType(“text/html;charset=UTF-8”);
PrintWriter out=response.getWriter();
//调用ConnectToDatabase
processRequest(请求、响应);
getEventsCount(请求、响应);
getAffiliatesCount(请求、响应);
getTotalWithdrawal(请求、响应);
如果(第页!=null){
getRequestDispatcher(“/dashboard.jsp”).include(请求、响应);
}否则{
out.println(“”);
println(“哦,突然!更改一些内容,然后再次尝试提交。”);
out.println(“”);
getRequestDispatcher(“/login.jsp”).include(请求、响应);
}
}
您的实现离这里很远。你需要像下面这样做。您可以使用JSP EL访问请求属性:
<p>Event Count is ${eventCount}</p>
<p>Affiliate Count is ${affiliateCount}</p>
<p>User Name is ${user.forename} ${user.surname}</p>
谢谢你的帮助。非常感谢
<p>Event Count is ${eventCount}</p>
<p>Affiliate Count is ${affiliateCount}</p>
<p>User Name is ${user.forename} ${user.surname}</p>
@WebServlet("/organizer")
public class UserLogin extends HttpServlet {
protected void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
@SuppressWarnings("Duplicates")
protected void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
String email = request.getParameter("email");
String password = request.getParameter("password");
User user = getUsert(emil password)
if(user != null){
request.setAttributes("eventCount", getEventsCount(email, password));
request.setAttributes("affiliateCount", getAffiliatesCount(email,password));
request.getRequestDispatcher("/dashboard.jsp").forward(request, response);
}else{
request.setAttribute("failedLogin", true);
request.getRequestDispatcher("/login.jsp").forward(request, response);
}
}
protected User getUser(String email String password){}
User user = null; //create a class user with 3 fields
// Query
if(rs.next()){
user = new User(rs.getInt("id"),
rs.getString("firstname"),
rs.getString("lastname"))
}
return user;
}
protected int getEventsCount(String email, String password)
throws ServletException, IOException {
// query and return result
return count;
}
protected void getAffiliatesCount(String email, String password)
throws ServletException, IOException {
// query and return result
return count;
}
}