java.sql.SQLException:无效句柄

Question

我正在尝试自学如何在java中连接到msaccess数据库。我已经设置了一个类来访问数据库，如下所示

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public abstract class AccessDBConnect2 {
    public static Connection connect(){
        String fileName = "C:/Users/Bridget/Documents/EmployeeSys.accdb";
        Connection con = null;
        try {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            String url = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb, *.accdb)};DBQ="+fileName;
            con = DriverManager.getConnection(url,"","");
        } catch (Exception e) {
            // Handle exceptions    ...
            System.out.println(e.toString());
            System.out.println("A problem accessing the database");
            e.printStackTrace();
        } finally {
            try { if(con!=null) {con.close();} } catch (Exception e) {}
        }
        return con;
    }
public static void closeConnection(Connection conn){
    try{
        conn.close();
    }catch (Exception e){
    }
}

然后我有我的代码，它只是试图从表中选择所有内容。我已经在msAccess中创建了表，代码似乎可以毫无问题地通过上述代码中的连接方法，表明它正在查找数据库并对其进行某种程度的访问。当我使用连接调用 prepareStatement（即代码行）时，就会出现问题：

stm = conn.prepareStatement(sql);

完整代码为：

import java.sql.*;
public class Program2{
public static void main(String[] args) {
        try{
            // Load the JDBC driver
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
        // Establishing db connection
        Connection conn = AccessDBConnect.connect();
        // Displaying all records from employee file
        System.out.println("Display records of all employees");
        display(conn);
        // Closing the connection
        AccessDBConnect.closeConnection(conn);
    }catch (Exception e){
        System.out.println("Error");
    }
}
// Display details of all employees
public static void display(Connection conn){
    PreparedStatement stm = null;
    // SQL statement
    String sql = "SELECT * FROM Employee";
    ResultSet rs;
    try {
        stm = conn.prepareStatement(sql);   // Prepare the SQL statement
        rs = stm.executeQuery();            // Execture the SQL statement
        // Navigate through the ResultSet and print
        while (rs.next()){
            int id = rs.getInt("id");
            String name = rs.getString("name");
            String gender = rs.getString("gender");
            String address = rs.getString("address");
            System.out.println("ID: t t" + id);
            System.out.println("Name: t t" + name);
            System.out.println("Gender: t" + gender);
            System.out.println("Address: t" + address);
            System.out.println(" ");
        }
    // Closing the resultSet
    rs.close();
    } catch (SQLException e) {
        e.printStackTrace();
    }
}
public void test(){
    int a = "hello";
}

}

Answer 1

您

收到错误，因为当您尝试调用.prepareStatement时，连接已关闭。AccessDBConnect2类包含一个finally块，该块在连接返回之前关闭连接。修复该类，使其保持连接打开状态。

顺便说一下，JDBC-ODBC 桥已经从 Java 8 中删除，并且实际上已经过时了。您可能对此替代方案感兴趣：

在没有 ODBC 的情况下从 Java 操作 Access 数据库

Answer 2

我已经删除了明显不正确的答案:)另一种可能性：

我认为问题出在您与数据库的连接上，请尝试将"C：/Users/Bridget/Documents/EmployeeSys.accdb"更改为
"C：\\Users\Bridget\Documents\EmployeeSys.accdb"