小编ati*_*ain的帖子

代码有什么问题,调试时有很多错误.我正在编写一个单例类的代码来连接数据库mysql.

这是我的代码

package com.glomindz.mercuri.util;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;

public class MySingleTon {
    String url = "jdbc:mysql://localhost:3306/";
    String dbName = "test";
    String driver = "com.mysql.jdbc.Driver";
    String userName = "root";
    String password = "";

    private static MySingleTon myObj;   
    private Connection Con ;
    private MySingleTon() {
        System.out.println("Hello");
        Con= createConnection();
    }

    @SuppressWarnings("rawtypes")
    public Connection createConnection() {
        Connection connection = null;
        try {
            // Load the JDBC driver
            Class driver_class = Class.forName(driver);
            Driver driver = (Driver) driver_class.newInstance();
            DriverManager.registerDriver(driver);
            connection = DriverManager.getConnection(url …

我不知道如何使用hashmap和while循环从我的数据库中检索数据.请帮助我.
我的代码是

    package com.glomindz.mercuri.dao;

    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.HashMap;

    import com.glomindz.mercuri.util.MySingleTon;

          public class UserServicesDAO {

private Connection connection;

public UserServicesDAO() {
    //connection = new MySingleTon().getConnection();
    connection = MySingleTon.getInstance().getConnection();

}

public void get_all_data() {
    HashMap<Integer, String> result = new HashMap<Integer, String>();
    String query = "SELECT * FROM spl_user_master";
    try {
        PreparedStatement stmt = connection.prepareStatement(query);
        boolean execute = stmt.execute();
        System.out.println(execute);
        ResultSet resultSet = stmt.getResultSet();
        System.out.println(resultSet.getMetaData());

    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } …