Question

我在NetBeans 8.2 IDE上创建了一个java项目，该程序在IDE上运行完美，但是当我尝试运行项目的.jar文件时，sqlite数据库没有连接，请指导我该怎么做？ P.S：我是堆叠溢出的新手，所以我不知道提出问题的确切方法！

以下是数据库的连接代码：

   public Connection connect1() {
    try {

        Class.forName("org.sqlite.JDBC");
    } catch (ClassNotFoundException ex) {
        Logger.getLogger(SQLiteJDBCDriverConnection.class.getName()).log(Level.SEVERE, null, ex);
    }
    String url = "jdbc:sqlite:SaeedGoldCastingDB.sqlite";
    Connection conn = null;
    try {
        conn = DriverManager.getConnection(url);
    } catch (SQLException e) {
        System.out.println(e.getMessage());
    }
    return conn;
}

通过给出绝对地址，它会抛出一个空指针eception：

run:

线程中的异常＆＃34; AWT-EventQueue-0＆＃34;显示java.lang.NullPointerException 在 DatabaseConnection.SQLiteJDBCDriverConnection.Login（SQLiteJDBCDriverConnection.java:83）在 goldsmith.billing.and.database.Login.btnLoginActionPerformed（Login.java:205）在goldsmith.billing.and.database.Login.access $ 000（Login.java:15）at goldsmith.billing.and.database.Login $ 1.actionPerformed（Login.java:90）在 javax.swing.AbstractButton.fireActionPerformed（AbstractButton.java:2022）在 javax.swing.AbstractButton中的$ Handler.actionPerformed（AbstractButton.java:2348）在 javax.swing.DefaultButtonModel.fireActionPerformed（DefaultButtonModel.java:402）在 javax.swing.DefaultButtonModel.setPressed（DefaultButtonModel.java:259）在 javax.swing.plaf.basic.BasicButtonListener.mouseReleased（BasicButtonListener.java:252）在java.awt.Component.processMouseEvent（Component.java:6533）at javax.swing.JComponent.processMouseEvent（JComponent.java:3324）at java.awt.Component.processEvent（Component.java:6298）at java.awt.Container.processEvent（Container.java:2236）at java.awt.Component.dispatchEventImpl（Component.java:4889）at java.awt.Container.dispatchEventImpl（Container.java:2294）at java.awt.Component.dispatchEvent（Component.java:4711）at java.awt.LightweightDispatcher.retargetMouseEvent（Container.java:4888）在 java.awt.LightweightDispatcher.processMouseEvent（Container.java:4525） at java.awt.LightweightDispatcher.dispatchEvent（Container.java:4466）在java.awt.Container.dispatchEventImpl（Container.java:2280）at java.awt.Window.dispatchEventImpl（Window.java:2746）at java.awt.Component.dispatchEvent（Component.java:4711）at java.awt.EventQueue.dispatchEventImpl（EventQueue.java:758）at at java.awt.EventQueue.access $ 500（EventQueue.java:97）at java.awt.EventQueue $ 3.run（EventQueue.java:709）at java.awt.EventQueue $ 3.run（EventQueue.java:703）at java.security.AccessController.doPrivileged（Native Method）at java.security.ProtectionDomain $ JavaSecurityAccessImpl.doIntersectionPrivilege（ProtectionDomain.java:80）在 java.security.ProtectionDomain $ JavaSecurityAccessImpl.doIntersectionPrivilege（ProtectionDomain.java:90）在java.awt.EventQueue $ 4.run（EventQueue.java:731）at java.awt.EventQueue $ 4.run（EventQueue.java:729）at java.security.AccessController.doPrivileged（Native Method）at java.security.ProtectionDomain $ JavaSecurityAccessImpl.doIntersectionPrivilege（ProtectionDomain.java:80）在java.awt.EventQueue.dispatchEvent（EventQueue.java:728）at java.awt.EventDispatchThread.pumpOneEventForFilters（EventDispatchThread.java:201）在 java.awt.EventDispatchThread.pumpEventsForFilter（EventDispatchThread.java:116）在 java.awt.EventDispatchThread.pumpEventsForHierarchy（EventDispatchThread.java:105）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:101）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:93）在java.awt.EventDispatchThread.run（EventDispatchThread.java:82）

以下是代码：

public class SQLiteJDBCDriverConnection {
     /**
     * Connect to a sample database
     */
    public String rate=null;
    public String date=null;


 public Connection connect1() {
    try {
        // SQLite connection string
        Class.forName("org.sqlite.JDBC");
    } catch (ClassNotFoundException ex) {
        Logger.getLogger(SQLiteJDBCDriverConnection.class.getName()).log(Level.SEVERE, null, ex);
    }
    String url = "jdbc:sqlite:C:\\Users\\Hashmi\\Documents\\NetBeansProjects\\Goldsmith-Billing-and-database\\src\\SourceFolder\\SaeedGoldCastingDB.sqlite";
    Connection conn = null;
    try {
        conn = DriverManager.getConnection(url);
    } catch (SQLException e) {
        System.out.println(e.getMessage());
    }
    return conn;
}
  public boolean Login(Login l){

   String idLogin = null ;
   String password = null;
   char[] pass = l.jPasswordField1.getPassword();
  String passString = new String(pass);
   String sql = "SELECT idLogin , password from Login where idLogin like '%"+l.jTextField_idLogin.getText()+"%';";
    try (Connection conn = this.connect1();
         Statement stmt  = conn.createStatement();
         ResultSet rs    = stmt.executeQuery(sql)){
        // loop through the result set
        while (rs.next()) {
          idLogin=rs.getString("idLogin");
          password=rs.getString("password");
         }
          if(idLogin.matches(l.jTextField_idLogin.getText() ) && password.matches(passString))
            return true;
           else
               return false;

    } catch (SQLException e) {
        System.out.println(e.getMessage());
    }
    return false;
 }
  public void UpdateLogin(String idLogin,String password){

     String sql = "UPDATE Login SET password=? WHERE idLogin like '%"+idLogin+"%';";
  try (Connection conn = this.connect1();
         PreparedStatement pstmt = conn.prepareStatement(sql))
    {

              pstmt.setString(1,password);
              pstmt.executeUpdate();

    } catch (SQLException e) {
        System.out.println(e.getMessage());
    }

      }     
   public void insertLogin(String idLogin,String password){

     String sql = "insert into Login(idLogin,password)values(?,?);";
  try (Connection conn = this.connect1();
         PreparedStatement pstmt = conn.prepareStatement(sql))
    {

              pstmt.setString(1,idLogin);
              pstmt.setString(2,password);
              pstmt.executeUpdate();



    } catch (SQLException e) {
        System.out.println(e.getMessage());
    }

      }     
  public boolean userCheck(Settings s){

   String idLogin = null ;
   String password = null;
   char[] pass = s.jPasswordField_OldPassword.getPassword();
   String passString = new String(pass);
   String sql = "SELECT idLogin , password from Login where idLogin like '%"+s.jTextField_useName1.getText()+"%';";
    try (Connection conn = this.connect1();
         Statement stmt  = conn.createStatement();
         ResultSet rs    = stmt.executeQuery(sql)){
        // loop through the result set



            while (rs.next())
                 {
                  idLogin=rs.getString("idLogin");
                  password=rs.getString("password");
                 }

                 if(idLogin.matches(s.jTextField_useName1.getText() ) && password.matches(passString))
            return true;
           else
               return false;




    } catch (SQLException e) {
        System.out.println(e.getMessage());
    }
    return false;
 }

Answer 1

您使用SQLite数据库文件的相对路径：

jdbc:sqlite:SaeedGoldCastingDB.sqlite

根据文件SaeedGoldCastingDB.sqlite的实际位置，Java可能无法在程序执行时找到它。

改为使用绝对路径。

运行项目

1 个答案: