java 连接 postgresql

package com.xxx.postgrepsql;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

/**
 * 数据库帮助类
 */
public class DBHelper {
    private static String url = "jdbc:postgresql://localhost:5432/Solution";
    private static String driver = "org.postgresql.Driver";
    private static String user = "postgres";
    private static String password = "18731362155";

    private Connection connection = null;

    public Connection getConnection() {
        return connection;
    }


    public PreparedStatement getStatement() {
        return statement;
    }


    private PreparedStatement statement = null;

    public DBHelper(String sql) {
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, user, password);
            statement = connection.prepareStatement(sql);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void close() {
        try {
            this.connection.close();
            this.statement.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

package com.xxx.postgrepsql;

import java.sql.*;

/**
 * 连接postgres数据库
 */
public class jdbcDemo {
    public static void main(String[] args) {
        String sql="select * from t_user";
        DBHelper dbHelper=new DBHelper(sql);
        try {
            ResultSet resultSet = dbHelper.getStatement().executeQuery();
            System.out.println("Id      username        password");
            while (resultSet.next()){
                System.out.println(resultSet.getString(1)+"          "+resultSet.getString(2)+"             "+resultSet.getString(3));
            }
            dbHelper.close();
        } catch (SQLException e) {
            dbHelper.close();
            e.printStackTrace();
        }

    }
}