MyEclipse에서 Struts를 사용하여 Derby 데이터베이스에 연결할 수 없습니다.

Question

struts 및 MyEclipse IDE을 처음 사용합니다.
나는 이름 및 비밀번호 소요의 MyEclipse 기본 데이터베이스 즉 더비에 저장하려고 로그인 응용 프로그램을 개발했다.
하지만 Derby DB에 연결되지 않아 로그인 세부 정보를 저장할 수 없습니다.
derby jar 파일을 프로젝트 lib 폴더에 저장하고 APP 폴더 테이블의 Derby 데이터베이스에 "로그인"테이블을 만들었습니다.

도와주세요.

LoginFormBean.java

package info.strutspkg; 

import javelin.servlet.http.HttpServletRequest; 

import org.apache.struts.action.ActionErrors; 
import org.apache.struts.action.ActionForm; 
import org.apache.struts.action.ActionMapping; 
import org.apache.struts.action.ActionMessage; 

public class LoginFormBean extends ActionForm { 

private String username = null; 
private String password = null; 

public ActionErrors validate(ActionMapping mapping, 
     HttpServletRequest request) { 

    ActionErrors actionErrors = new ActionErrors(); 

    if(username == null || username.length() < 1) { 
     actionErrors.add("userName", new ActionMessage("error.username")); 
    } 
    try { 
    if(password == null || password.length()<1) { 
     actionErrors.add("password", new ActionMessage("error.password")); 
    } 
    }catch(Exception e) { 
     e.printStackTrace(); 
    } 
    return actionErrors ; 
} 

public void setUsername(String username) 
{ 
    this.username = username; 
} 
public String getUsername() 
{ 
    return username; 
} 
public void setPassword(String password) 
{ 
    this.password = password; 
} 
public String getPassword() 
{ 
    return password; 
} 
} 

LoginActionClass.java

package info.strutspkg; 


import java.sql.Connection; 

import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

import login.logindao.Logindao; 

import org.apache.struts.action.*; 

public class LoginActionClass extends Action{ 

    public ActionForward execute(ActionMapping mapping,ActionForm form,HttpServletRequest request,HttpServletResponse response)throws Exception 
    { 
     Connection con=null; 
      String key=null; 
    try{ 

     LoginFormBean lf = (LoginFormBean)form; 
     String uname = lf.getUsername(); 
     String pwd = lf.getPassword(); 


     Logindao dao=new Logindao(); 

     int i=dao.insert(uname,pwd); 

     if(i>0){ 
     key="success"; 
     } 
     else 
     { 
     key="failure"; 
     } 
     } 
     catch(Exception e){ 
     e.printStackTrace(); 

     } 
    return mapping.findForward(key); 
    } 
    } 

Logindao.java

package login.logindao; 

import java.sql.Connection; 
import java.sql.PreparedStatement; 
import java.sql.SQLException; 

import db.dbconnection.DBConnect; 

public class Logindao { 

    public int insert(String uname,String pwd){ 
      int r=0; 
      PreparedStatement ps = null; 
      //get connection object from DBConnection class 
      Connection conn = DBConnect.createConnection(); 
      System.out.println("Connection"+conn); 

      try{ 
      //use PreparedStatement to insert the values of username and password 
      ps=conn.prepareStatement("insert into login(username,password) values(?,?)"); 
      ps.setString(1, uname); 
      ps.setString(2, pwd); 
      r = ps.executeUpdate(); 
      } 
      catch(SQLException ex) { 
      try { 
      ps.close(); 
      conn.close(); 
      } catch (SQLException e) { 
      e.printStackTrace(); 
      } 
      System.err.println("SQLException: " + ex.getMessage()); 
      } 
      return r; 

     } 

} 

DBConnect.java

package db.dbconnection; 

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.Statement; 

public class DBConnect { 

     public static Connection createConnection(){ 

    Connection conn = null; 
    String url = "jdbc:derby://localhost:1527/myeclipse/derby;create=true"; 
    String userName="lalitha"; 
    String password="lalitha"; 
    String tableName = "login"; 


     try 
      { 
       Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance(); 
       //Get a connection 
       conn = DriverManager.getConnection(url,userName,password); 
      } 
      catch (Exception except) 
      { 
       except.printStackTrace(); 
      } 
      return conn; 
     } 
     } 

스택 트레이스 :

**Connectionorg.apache.derby.client.net.NetConnection40@161401f 
java.lang.NullPointerException 
    at login.logindao.Logindao.insert(Logindao.java:27) 
    at info.strutspkg.LoginActionClass.execute(LoginActionClass.java:28) 
    at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58) 
    at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67) 
    at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51) 
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190) 
    at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304) 
    at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190) 
    at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283) 
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913) 
    at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:810) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) 
    at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:81) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) 
    at org.jboss.web.tomcat.security.CustomPrincipalValve.invoke(CustomPrincipalValve.java:39) 
    at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:153) 
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:59) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) 
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856) 
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744) 
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527) 
    at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112) 
    at java.lang.Thread.run(Thread.java:662) 
WARN [ActionMapping] Unable to find 'null' forward. 

Answer 1

는 데이터베이스 생성에서 예외를 잡는다 때 기능 createConnection()는 NULL을 반환하기 때문에 당신은 NullPointerException이 얻을 :

Connection conn = null; 
    try 
     { 
      ... 
     } 
     catch (Exception except) 
     { 
      except.printStackTrace(); 
     } 
     //conn is null 
     return conn; 

을

except.printStackTrace();의 출력은 h 그 특정 오류를 찾으십시오.

데이터베이스 설정에서 뭔가를해야한다고 생각하지만 이론을 뒷받침 할 충분한 정보를 제공하지 않았습니다.