こんにちは、私は jsp とサーブレットにかなり慣れていないので、簡単なクエリを実行できなかった理由を理解するのに問題があります。コードは、ユーザーサーブレットがユーザーから送信されたデータを照会し、それをデータベースと照合するログインページ用であり、一致が見つかると login==true を返し、そこで別のクエリが実行され、一致する従業員 ID 番号が取得されます。ユーザー名とパスワードで
import java.sql.Connection;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.*;
import javax.servlet.*;
import java.io.*;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Driver;
import java.sql.DriverManager;
import javax.servlet.http.HttpSession;
public class Login extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException{
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
HttpSession session = request.getSession();
Connection conn = null;
PreparedStatement prepState = null;
Statement state = null;
ResultSet result = null;
boolean login = false;
String username = request.getParameter("username");
String password = request.getParameter("password");
String checkLogin = ("SELECT * FROM users WHERE username = ? AND password = ?");
try{
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/matrix","","");
prepState = conn.prepareStatement(checkLogin);
prepState.setString(1, username);
prepState.setString(2, password);
result = prepState.executeQuery();
login = result.next();
if(login){
out.println("login");
String id = result.getString(1);
String getUser = ("SELECT empLastName, empFirstName FROM employees WHERE empID = ? ");
prepState = conn.prepareStatement(getUser);
prepState.setString(1, id);
result = prepState.executeQuery();
String first = result.getString(2);
String last = result.getString(1);
out.println("<html>");
out.println(first + " " + last);
out.println("</html>");
}
}catch(Exception e){
out.println("ERROR");
e.printStackTrace(System.err);
}
}catch(Exception db){
} finally {
out.close();
}
}
ここに私が得るエラーがあります
INFO: The start() method was called on component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Matrix]] after start() had already been called. The second call will be ignored.
java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1075)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3566)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3498)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:919)
at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4004)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1284)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2312)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2122)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:774)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:49)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:375)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:289)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at Login.processRequest(Login.java:57)
at Login.doPost(Login.java:119)
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:304)
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:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
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:662)