I wrote a login web and it can't work well. It may be some problem of MySQL connecting.
Here is the code. It's simple. There are ServletLogin.java and a index.jsp.
ServletLogin.java
package Login;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.sql.*;
public class ServletLogin extends HttpServlet {
private static final long serialVersionUID = 1L;
private String name;
private String pass;
public ServletLogin() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
String printout = "";
this.name = request.getParameter("username");
this.pass = request.getParameter("password");
if (name == "" || name == null || name.length() > 20) {
try {
printout = "２０字以内ユーザネームを再入力ください";
request.setAttribute("message", printout);
response.sendRedirect("index.jsp");
return;
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
if (pass == "" || pass == null || pass.length() > 20) {
try {
printout = "２０字以内のパスワードを再入力ください";
request.setAttribute("message", printout);
response.sendRedirect("index.jsp");
return;
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
// database driver
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (Exception e) {
// TODO: handle exception
System.out.println("Class not Found Exception");
}
// create url
String url = "jdbc:mysql://localhost:3306/databasedemo";
try {
Connection conn = DriverManager.getConnection(url,"root","");
Statement stmt = conn.createStatement();
String sql = "select * from userinfo where username='"+name+"' and password= '"+pass+"'";
ResultSet rs = stmt.executeQuery(sql);
if (rs.next()) {
if (this.name.equals(rs.getString(1))||this.pass.equals(rs.getString(2))) {
response.sendRedirect("success.jsp");
}
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
index.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>ログイン</title>
<script type="text/javascript">
function changeImg()
{
document.getElementById("validateCodeImg").src="${pageContext.request.contextPath}/CheckCodeImage?" + Math.random();
}
</script>
</head>
<body>
<form action="${pageContext.request.contextPath}/ServletLogin">
<table border="0" align="center">
<tr height="30"></tr>
<tr align="center">
<td colspan="2"><font size="20">JAVA WEB</font></td>
</tr>
<tr height="30"></tr>
<tr height="50">
<td>ユーザネーム</td>
<td><input type="text" name="username" placeholder="ユーザネームを入力してください"></td>
</tr>
<tr height="50">
<td>パスワード</td>
<td><input type="password" name="password" placeholder="パスワードを入力してください"></td>
</tr>
<tr height="50">
<td><img alt="認めない" src="${pageContext.request.contextPath}/CheckCodeImage"
id="validateCodeImg" onclick="changeImg()">
</td>
<td><input type="text" name="checkcode" placeholder="右側の文字を入力してください"></td>
</tr>
<tr height="50">
<td colspan="2" align="center">
<input type="submit" name="login" value="ログイン">
</td>
</tr>
</table>
</form>
</body>
</html>
And here is my database called databasedemo.
+--------+----------+----------+
| userid | username | password |
+--------+----------+----------+
| 1 | Jack | 123456 |
| 2 | Mary | 654321 |
+--------+----------+----------+
I think I am stucked with command in ServletLogin.java. I was supposed to submit the form and it would turn to ServletLogin.java and do the command.
If the username and the password are null, recording to the code in Servlet.java, it will go back to index.jsp. And it went very well.
But if the username and the password are the same as it in my database, it should have to go to the page success.jsp. But when I run it, it shows nothing. Seems it has not been submitted and do the command in Servletlogin.java. and the Url shows http://localhost:8080/LoginDemo/ServletLogin?username=Jack&password=123456&checkcode=Axww&login=%E3%83%AD%E3%82%B0%E3%82%A4%E3%83%B3
I'm so confused of it. I think I have problem about connecting to MySQL. But I don't know how to fix it. Please help me about it...
UPDATE
I have solved my problem!
When I run the code, the Exception shows Class not Found Exception java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost:3306/databasedemo. This is a exception of jdbc Driver.
When this exception shows, there's four reason:
- Wrong URL. Please check the right code:
Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/XX","root","XXXX" - Wrong Driver declaration, the right one is :
com.mysql.jdbc.Driver - mysql-connector-java-5.1.40.jar must be the same version as your MySQL.
- mysql-connector-java-5.1.40.jar has been put to the wrong position. The right position is to copy it in WEB-INF file.
As for me, I put .jar in the wrong position. And When I copy it in the file WEB-INF, my code run well. I hope this will help someone. And my code above is a simple webpage of login. I will continue to complete this java project.
And Thanks for everyone answered my question. @Ravi Kumar pointed out one of my mistakes, and I corrected it. It's a big mistake of me using MySQL.
