Servlet錯誤 - 檢查多個變量

Question

import java.io.IOException; 
import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 

import javax.servlet.ServletException; 
import javax.servlet.annotation.WebServlet; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

import com.mysql.jdbc.PreparedStatement; 

/** 
* Servlet implementation class Login 
*/ 
@WebServlet("/Login") 
public class Login extends HttpServlet { 
    private static final long serialVersionUID = 1L; 

    /** 
    * @see HttpServlet#HttpServlet() 
    */ 
    public Login() { 
     super(); 
     // TODO Auto-generated constructor stub 
    } 

    /** 
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) 
    */ 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
     // TODO Auto-generated method stub 
     response.getWriter().append("Served at: ").append(request.getContextPath()); 
    } 

    /** 
    * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) 
    */ 
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 



     response.setContentType("text/html"); 
     Connection conn = null; 
     String url="jdbc:mysql://localhost:3306/"; 
     String dbName="Tamir"; 
     String driver="com.mysql.jdbc.Driver"; 



    try{ 
     request.setAttribute("message", ""); 
     String nick = request.getParameter("check_name"); 
     String password = request.getParameter("check_password"); 


     Class.forName(driver).newInstance(); 
     conn = DriverManager.getConnection(url+dbName,"root", "tamir"); 
     //admin check 
     /* 
     java.sql.PreparedStatement st2 = conn.prepareStatement("SELECT * FROM users WHERE nickname = ? or email = ? and password = ? and admin = T"); 
     st2.setString(1, nick); 
     st2.setString(2, nick); 
     st2.setString(3, password); 
     ResultSet r2=st2.executeQuery(); 

     if(r2.next()) { 
     request.getSession().setAttribute("admin", nick); 
    } 
    */ 
     //regular check 
     java.sql.PreparedStatement st = conn.prepareStatement("SELECT * FROM users WHERE nickname = ? or email = ? and password = ?"); 
     st.setString(1, nick); 
     st.setString(2, nick); 
     st.setString(3, password); 
     ResultSet r1=st.executeQuery(); 

     if(r1.next()) { 


      request.getSession().setAttribute("user", nick); 
      request.getRequestDispatcher("/tf2main.jsp").forward(request, response); 


     } else { 



     request.setAttribute("message", "Username or password are incorrect."); 
     request.getSession().setAttribute("user", null); 
     request.getRequestDispatcher("/Login.jsp").forward(request, response); 

     } 

    }catch (Exception ex) { 
     System.out.println("Error"); 
    } 
    } 

} 

你好。所以我已經完成了上面的代碼，它的工作完美，但是當我添加註釋[我真的需要，爲了檢查他是否是管理員...對我而言是Cruical]，它只是由於某種原因拋出異常。

我想過的唯一的其他靈魂就是重新定位到另一個servlet，但是不可能做同樣的動作，但這是不可能的，所以我有點卡住了，你也不能使用ERB。

我試過了一切，沒有任何工作。

編輯：被扔的錯誤是：

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'T' in 'where clause' 
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) 
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) 
at java.lang.reflect.Constructor.newInstance(Unknown Source) 
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) 
at com.mysql.jdbc.Util.getInstance(Util.java:408) 
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:943) 
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973) 
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909) 
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527) 
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680) 
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2487) 
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858) 
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1966) 
at Login.doPost(Login.java:68) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) 
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:222) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) 
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) 
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041) 
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603) 
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
at java.lang.Thread.run(Unknown Source) 

Answer 1

更新的查詢是這樣的：

java.sql.PreparedStatement st2 = 
    conn.prepareStatement("SELECT * FROM users WHERE nickname = ? or email = ? and password = ? and admin = 'T'"); 

注意T周圍的單引號中查詢。