我使用的是xampp mysql,這段代碼是針對JDBC程序的。實際上有兩個類,一個是dbconnect.java,另一個是login.java。我想訪問另一個類(即login.java)中的連接對象(即conn)。但我沒有適當的想法,我已經在這裏包含代碼,請告訴我什麼是問題和解決方案是什麼?如何訪問java中另一個類的連接對象?
這是dbconnect.java
package stundentrecord;
import java.sql.Connection;
import java.sql.DriverManager;
public class dbconnect {
public void conect(){
Connection con = null;
String url = "jdbc:mysql://localhost:3306/";
String db = "studentRecord";
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String pass = "";
try{
Class.forName(driver);
con = DriverManager.getConnection(url + db, user, pass);
if(con==null){
System.out.println("Connection cannot be established");
}
// con.close();
} catch (Exception e) {
System.out.println(e);
}
}
}
代碼,這裏是從另一個類名爲login.java
if(source==login){
if(username!=null && password!=null) {
Connection conn= null;
Statement stmt = null;
dbconnect db = new dbconnect();
db.conect();
String query = "SELECT * from userlogin";
try{
stmt=(Statement) conn.createStatement(); // here is the problem
ResultSet rs = stmt.executeQuery(query); // here is the problem
while (rs.next()) {
String user = rs.getString("username");
String pass=rs.getString("password");
System.out.println("Welcome "+user);
}
} catch(SQLException ex){
ex.getMessage();
}
StundentRecord SR = new StundentRecord();
} else {
JOptionPane.showMessageDialog(null,"Username or password field is empty","error !!",JOptionPane.ERROR_MESSAGE);
}
}
什麼是真正的問題,以及如何解決它的代碼?
請格式化您的代碼,這是不可讀的。遵循Java約定(類是第一個大寫字母,等等......) – m0skit0 2013-02-19 15:00:48
@SotiriosDelimanolis如果你閱讀代碼,你會明白設計問題 – 2013-02-19 15:01:29
@LuiggiMendoza如果你可以閱讀任何東西,那就是。 – m0skit0 2013-02-19 15:02:06