Question

我的登录表格不起作用，请帮助我......

public class LoginServlet extends HttpServlet {

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    String userName=request.getParameter("userName");
    String password=request.getParameter("password");
     DataPersistor d=new DataPersistor();
    try {
        if( d.isValidateUser(userName, password)){
               HttpSession session=request.getSession();
         session.setAttribute("name", userName);
         response.sendRedirect("index.jsp");
        }



         else{
             response.sendRedirect("login.jsp");

         }
    } catch (SQLException ex) {
        Logger.getLogger(LoginServlet.class.getName()).log(Level.SEVERE, null, ex);
    }


    } 




}

这是我的数据持久性等级。我从数据库获得了价值，

public class DataPersistor {
    Connection con;

public DataPersistor() {
    con = DBConnector.getConnection();
}

public void registerUser(User user) {
    try {
        Statement stmt = con.createStatement();
        String query = "INSERT INTO user VALUES ('" + user.getUserName() + "','" + user.getPassword() + "','" + user.getEmail() + "','" + user.getLastName() + "','" + user.getFirstName() + "','false')";
        stmt.execute(query);



    } catch (SQLException ex) {
        Logger.getLogger(DataPersistor.class.getName()).log(Level.SEVERE, null, ex);
    }





}
public boolean isValidateUser(String username,String password) throws SQLException{
    boolean result=false;
    PreparedStatement ps;
     Statement stmt = con.createStatement();
        String query = "SELECT * FROM  user WHERE username='" + username + "' and password='"+password+"'";
        ps=con.prepareStatement(query);
        ps.setString(1,username);
        ps.setString(2, password);

        ResultSet rs=ps.executeQuery();

        if(rs.next()==true){

            result=true;
        }
        return result;





}

}

清洁和构建后

Jul 29, 2012 8:51:46 PM com.asiahospital.servlet.LoginServlet doPost
SEVERE: null
java.sql.SQLException: Parameter index out of range (1 > number of parameters, which is 0).
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
    at com.mysql.jdbc.PreparedStatement.checkBounds(PreparedStatement.java:3729)
    at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:3713)
    at com.mysql.jdbc.PreparedStatement.setString(PreparedStatement.java:4553)
    at com.asiahospital.db.DataPersistor.isValidateUser(DataPersistor.java:50)
    at com.asiahospital.servlet.LoginServlet.doPost(LoginServlet.java:32)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:619)`enter code here`

Answer 1

看起来您的连接尚未正确初始化。

Statement stmt = con.createStatement();

检查从

返回的内容

DBConnector.getConnection()

从您更新的帖子（！），问题是您准备好的语句不包含任何'？'占位符字符。

public boolean isValidateUser(String username, String password) throws SQLException {
    boolean result = false;

    String query = "SELECT * FROM  user WHERE username='?' and password='?'";
    PreparedStatement ps = con.prepareStatement(query);
    ps.setString(1, username);
    ps.setString(2, password);

    ResultSet rs = ps.executeQuery();

    if (rs.next() == true) {
       result = true;
    }

    return result;
}

登录表单在我的应用程序中不起作用

1 个答案: