MySql, JSP, javaBeans! help!

doori · May 18th, 2005, 01:46 PM

Hello everybody..
i'm trying to develop a registeration code using JSP, MySql and Java beans..
but it doesn't work!!
well.. the idea is the following:
first i'm using a studentBean to set and get the relevant information of the student!
-------------------------------
package myBeans;

public class studentBean {
  int reg_num;
  String name;
  String surname;
  String course;
  String username;

  public void setusername(String username) {
      this.username = username;
  }

  public void setname(String name) {
      this.name = name;
  }

  public void setsurname(String surname) {
      this.surname = surname;
  }

  public void setcourse(String course) {
      this.course = course;
  }

  public void setreg_num(int reg_num) {
      this.reg_num = reg_num;
  }

  public int getreg_num() {
      return reg_num;
  }

  public String getusername() {
      return username;
  }

  public String getFullName() {
      return name + " " + surname;
  }

  public String getcourse() {
      return course;
  }

}
-------------------------------------------
then i'm using register.jsp

<html>
<head><title>Welcome to the Registration Page</title></head>
<body>
  <h3 align="center">Registration Page</h3>
<form action="checkregister.jsp" method="POST">
  <table border="0">
   <tr><td>Username:<input type="text" name="username"/></td></tr>
   <tr><td>Name :<input type="text" name="name"/></td></tr>
   <tr><td>Surname :<input type="text" name="surname"/></td></tr>
   <tr><td> Course:
       <select name = "course">
      <option value = "BSc CS">Computer Science</option>
      <option value = "BSc CoE">Computer Engineering</option>
      <option value = "BSc GD">Graphic Design</option>
      <option value = "BSc CE">Civil Engineering</option>
      <option value = "BSc AE">Automotive Engineering</option>
       </select>
    </tr> </td>
   <tr><td><input type="submit" value="Sign Up"/></td></tr>
  </table>
  </form>
</body>
</html>
--------------------------------------------------
here's the Java Bean:
authBean2.java
package myBeans;

import java.sql.*;
import java.sql.ResultSet;
import myBeans.studentBean;
import java.util.Vector;
import javax.servlet.jsp.JspWriter;

public class authBean2 {

  Connection cn = null;

  public authBean2() {
      try {
        Class.forName("com.mysql.jdbc.Driver");
       cn = DriverManager.getConnection("jdbc:mysql://localhost/ProjectDB?user=root&password=acsc404");
    }
    catch (Exception e) { System.out.println(e.getMessage()); }

  }

  public studentBean addStudent(String username, String name,
                                String surname, String course, JspWriter out) {
    ResultSet rs = null;
    Statement st = null;
    String sqlStr = null;
    try {
      st = cn.createStatement();
      sqlStr = " SELECT reg_num FROM student WHERE username = ' " + username + "' " ;
      rs = st.executeQuery(sqlStr);
      if (rs.next()) {
       return null;
       }
      else {
        st = cn.createStatement();
        sqlStr = " INSERT INTO student " +
        "(username, name, surname, course)"+
        " VALUES" +
        "(' " + username +" ' , ' " + name + " ' , ' " + surname + " ', ' " + course + " ') ";
        rs = st.executeQuery(sqlStr);
           while(rs.next()) {
              studentBean stud = new studentBean();
           stud.setusername(rs.getString(1));
           }

                }

            }

    catch (Exception e) {
      try{out.println(sqlStr);out.println(e.getMessage() ); }
          catch (Exception dum) {return null;}
       }
     }
   }

------------------------------------
and here's the checkregister.jsp
<html>
  <head></head>
  <body>

  <%@ page import="myBeans.studentBean" %>
  <jsp:useBean id="xx" scope="session" class="myBeans.authBean2"/>

   <% if (request.getParameter("username") != null) {

          studentBean student;
          student = xx.addStudent(request.getParameter("username"),
                                             request.getParameter("name"),
                                              request.getParameter("surname"),
                                              request.getParameter("course"), out);
          if (student != null) {
          session.setAttribute("student", student);
          %>
          <p>Hello <%= ((studentBean) session.getAttribute("student")).getFullName()%>.
               your User Name is:
               <%= ((studentBean) session.getAttribute("student").getusername()%> <br/>
               and your Registeration Number is:
              <%= ((studentBean) session.getAttribute("student").getreg_num()%><br/>
              use these information to login!.
          </p>
    <%
    }
    else {
      String msg ="The user name already exists, please choose a different user name!";
       request.setAttribute("msg",msg);

         %>
    <jsp:forward page="register.jsp"/>
    <%
    }
    }
  %>
  </body>
</html>
----------------------------------
when i'm trying to compile the ant tool show this error message while compiling the authBean2.java
compile:
    [javac] Compiling 3 source files to C:\apps\Project1\build\WEB-INF\classes
    [javac] C:\apps\Project1\src\myBeans\authBean2.java:52: missing return state
ment
    [javac] }
    [javac] ^
    [javac] 1 error

what's the problem?

cavenaghi · May 30th, 2005, 08:51 PM

here is my code have been complie vell!

<%@ page contentType="text/html;charset=gb2312"%>
<html><head><title>login</title></head>
<body>
<form name="login" action="check.jsp" method="post">
    userÂ£Âº<input type="text" name="admin"><br>
    passwordÂ£Âº<input type="password" name="password"><br>
    <input type="submit" value="login"><br>
</form>
</body>
</html>
<%
    String error=request.getParameter("error");
    //error=new String(error.getBytes("8859_1"),"gb2312");
    if(error==null) {}
    else{
        %>
        <%=error%>
        <%
    }
%>

then

<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="login.CheckBean"%>
<%
    String admin = request.getParameter("admin");
    String password = request.getParameter("password");
%>
<jsp:useBean id="checkBean" class="com.ice.login.CheckBean"/>
<jsp:setProperty name="checkBean" property="admin" value="<%= admin.trim() %>"/>
<jsp:setProperty name="checkBean" property="password" value="<%= password.trim() %>"/>
<%
    String result = checkBean.checkIt();
    if(result.equals("rightÂ£Â¡")){
        session.setAttribute("admin",admin);
        response.sendRedirect("main.jsp");
    }
    else
    {
        %>
        <jsp:forward page="index.jsp">
            <jsp:param name="error" value="<%=result%>"/>
        </jsp:forward>
        <%
    }
%>

db.java

import java.sql.*;

public class DB {

    private Connection conn;
    private Statement stmt;
    private ResultSet rs;

    public DB() {
        try {
            Class.forName("org.postgresql.Driver");
            conn = DriverManager.getConnection("jdbc:postgresql://localhost:5432/news?user=admin&&password=");
            stmt = conn.createStatement();
        }
        catch(Exception e) {
            System.out.println(e);
        }
    }

    public void update(String sql) {
        try {
            stmt.executeUpdate(sql);
        }
        catch(Exception e) {
            System.out.println(e);
        }
    }

    public ResultSet quarry(String sql) {
        try {
            rs = stmt.executeQuery(sql);
        }
        catch(Exception e) {
            System.out.println(e);
        }
        return rs;
    }

}

checkbean.java

import java.sql.*;

public class CheckBean {

    private String message="",admin,password;
    private DB db;

    public CheckBean() {
        db = new DB();
    }

    public void setAdmin(String admin){
        this.admin = admin;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String checkIt() {
        try {
            ResultSet rs = db.quarry("select * from administrator where admin='"+this.admin+"'");
            while(rs.next()){
                String pws = rs.getString("password").trim();
                if(pws.equals(this.password)){
                    message = "rightÂ£Â¡";
                }
                else message = "password wrongÂ£Â¡";
                return message;
            }
            message = "no this userÂ£Â¡";
        }
        catch(Exception e) {
            System.out.println(e);
        }
        return message;
    }

}

if you have more program sent mail to me

javadude · June 2nd, 2005, 06:17 AM

hi,

the addStudent() method returns an object of studentBean type
but the source code seems to b missing that return statment.
try to make change to addStudent() method as follows

public studentBean addStudent(String username,
    String name, String surname, String course, JspWriter out) {
    ResultSet rs = null;
    Statement st = null;
    String sqlStr = null;
    try {
      st = cn.createStatement();
      sqlStr = " SELECT reg_num FROM student WHERE username = ' " + username + "' " ;
      rs = st.executeQuery(sqlStr);
      if (rs.next()) {
       return null;
       }
      else {
        st = cn.createStatement();
        sqlStr = " INSERT INTO student " +
        "(username, name, surname, course)"+
        " VALUES" +
        "(' " + username +" ' , ' " + name + " ' , ' " + surname + " ', ' " + course + " ') ";
        rs = st.executeQuery(sqlStr);
        studentBean stud = new studentBean();
           while(rs.next()) {

           stud.setusername(rs.getString(1));
           }
         return stud;
        }

    }

    catch (Exception e) {
      try{out.println(sqlStr);out.println(e.getMessage() ); }
          catch (Exception dum) {return null;}
       }
     }
     return null;
}