java - 将结果数组从类返回到其他类 java

Question

首先我对我的英语感到抱歉，我是 Java 编程新手，我正在尝试从数据库获取结果值。 jdbc derby 上的类到另一个类这是我的代码:

package myjavaproject;

import java.sql.*;

public class Db {

private static String dbURL = "jdbc:derby://localhost:1527/hotels;create=true";
private static String tableName = "users";
// jdbc Connection
private static Connection conn = null;
private static Statement stmt = null;
public String data = null;

public static void main(String[] args) {
    createConnection();
    shutdown();
}

private static void createConnection() {
    try {
        Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
        //Get a connection
        conn = DriverManager.getConnection(dbURL);
    }
    catch (Exception except) {
        except.printStackTrace();
    }
} 

public static String selectUsers() {
    try {
        stmt = conn.createStatement();
        ResultSet results = stmt.executeQuery("select * from " + tableName);
        Results name = new Results();
        if(results.next()){
            name.setName(results.getString("name"));
            String rs = results.getString("name");
            //return rs;
        }


        results.close();
        stmt.close();
    } 
    catch (SQLException sqlExcept) {
        sqlExcept.printStackTrace();
    }
    return null;
}

private static void shutdown() {
    try {
        if (stmt != null) {
            stmt.close();
        }
        if (conn != null) {
            DriverManager.getConnection(dbURL + ";shutdown=true");
            conn.close();
        }
    } 
    catch (SQLException sqlExcept) {
    }

}

}

Answer 1

您可能真正想要的是一个服务类，它充当 Controller 来为您配置所有内容。

类似于:

public class Service() {
   private Db databaseConnection;
   private List<User> users;

   public Service() {
      databaseConnection = new Db();
   }

   public List<Users> getUsers() {
        users = new ArrayList<User>();
        rs = databaseConnection.selectUsers(); //you'd need to change this to return the list of users, or to return the result set
        if (rs != null && rs.size() > 0) {
            while(rs.hasNext()) {
                 User aUser = new User();
                 aUser.setName(rs.next().get("Name")); //pseudo-code
                 users.add(aUser);
            }
        }
        return users;
   }
}