Question

大家好我不熟悉Java并开始学习java / jsp / servlets这个项目。我有一个Oracle表（名为giris），其中包含用户名（kullanici）和密码（sifre）。

英语不是我的第一语言或第二语言，所以看看我的代码，你会理解我的斗争。

我有girisDTO.java用于获取set方法和构造函数：

package tr.gov.ptt.rehberwebprj.dto;


public class GirisDTO {

private String kullanici;
private String sifre;

public GirisDTO()
{

}


public String getKullanici() {
    return kullanici;
}

public void setKullanici(String kullanici) {
    this.kullanici = kullanici;
}

public String getSifre() {
    return sifre;
}

public void setSifre(String sifre) {
    this.sifre = sifre;
}



 }

我有VTBaglanti.java用于数据库连接：

package tr.gov.ptt.rehberwebprj.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;


public class VTBaglanti {

public static Connection baglantiGetir() throws ClassNotFoundException,      SQLException
{
  Class.forName("oracle.jdbc.driver.OracleDriver");
  Connection conn=
  DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe", "kurs1", "ptt");
  return null;

}
public static void baglantiKapat(Connection p_conn) throws SQLException
{
    p_conn.close();

}

}

我有GirisDAO.java用于连接以外的数据库操作：

package tr.gov.ptt.rehberwebprj.dao;

import java.sql.*;
import tr.gov.ptt.rehberwebprj.dto.GirisDTO;
import tr.gov.ptt.rehberwebprj.util.VTBaglanti;

public class GirisDAO {

public static boolean giriseYetkilimi(GirisDTO p_giris) 
        throws ClassNotFoundException, SQLException
{
    String vtSifre=null;
    Connection conn= VTBaglanti.baglantiGetir();
    PreparedStatement ps = conn.prepareStatement("select sifre from giris where kullanici=?");
        ps.setString(1, p_giris.getKullanici());
        ResultSet rs = ps.executeQuery();
            while(rs.next())
            {
                vtSifre=rs.getString("sifre");
            }
            rs.close();

            if (vtSifre != null && vtSifre.equals(p_giris.getSifre()))
            {
            return true;
            }
               else
            {
            return false;
            }

}
}

我写了一个GirisDAOTest.java类来测试GirisDAO是否正常工作但是它给了我一个错误。

package tr.gov.ptt.rehberwebprj.test;

import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import tr.gov.ptt.rehberwebprj.dao.GirisDAO;
import tr.gov.ptt.rehberwebprj.dto.GirisDTO;


public class GirisDAOTest {

public static void girisKontrolTest() {

    try {
        GirisDTO giris= new GirisDTO();
        giris.setKullanici("eda");
        giris.setSifre("1234");

        boolean sonuc = GirisDAO.giriseYetkilimi(giris);

    } catch (ClassNotFoundException ex) {
        ex.printStackTrace();
    } catch (SQLException ex) {
        ex.printStackTrace();
    }

    if (true)
    {
        System.out.println("Giriş başarılı.");
    } else 
    {
        System.out.println("Kullanıcı adı  ya da şifre yanlıs");
    }

}


public static void main(String[] args) {

    girisKontrolTest();

}
}

我的错误是：

Exception in thread "main" java.lang.NullPointerException
at tr.gov.ptt.rehberwebprj.dao.GirisDAO.giriseYetkilimi(GirisDAO.java:15)
at tr.gov.ptt.rehberwebprj.test.GirisDAOTest.girisKontrolTest(GirisDAOTest.java:20)
at tr.gov.ptt.rehberwebprj.test.GirisDAOTest.main(GirisDAOTest.java:41)
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)

Java-Oracle Project-- java.lang.NullPointerException错误

0 个答案: