Java数据库连接

package com;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;


 public class ConnDB {
	private final static String username = "root";
	private final static String password = "123456";
	private final static String url = "jdbc:mysql://localhost:3306/test";
	private final static String dbDriver = "com.mysql.jdbc.Driver";
	private static Connection con = null;

        //加载数据库驱动
	public ConnDB() {
		// TODO Auto-generated constructor stub
		try {
			Class.forName(dbDriver).newInstance();
			System.out.println("数据库加载成功！");
		} catch (Exception e) {
			System.out.println("数据库加载失败！");
		}
	}

        //连接数据库
	public static boolean createConnection() {
		try {
			con = DriverManager.getConnection(url, username, password);
			con.setAutoCommit(true);
			System.out.println("数据库连接成功");
		} catch (Exception e) {
			System.out.println("数据库连接失败");
		}
		return true;
	}

	// 数据库更新操作
	public boolean excuteUpdate(String sql) {
		if (con == null) {
			createConnection();
		}
		try {
			Statement st = con.createStatement();
			int count = st.executeUpdate(sql);
			System.out.println("影响操作数：" + String.valueOf(count));
		} catch (Exception e) {
			System.out.println("数据库更新失败");
		}
		return true;
	}

	// 数据库查询操作
	public ResultSet executeQuery(String sql) {
		ResultSet rs = null;
		if (con == null) {
			createConnection();
		}
		try {
			Statement st = con.createStatement();
			rs = st.executeQuery(sql);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			return null;
		}
		return rs;

	}
        //释放数据库连接
	public void closeConnection() {
		if (con != null) {
			try {
				con.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

	public static void main(String args[]) {
		ConnDB con = new ConnDB();
		QueryName conn = new QueryName();
		String sql = "select * from tb_user";
		String sql1 = "select count(*) count from tb_user";
		ResultSet rs = con.executeQuery(sql1);
		try {
			int count1 = rs.getInt("count");
			System.out.println("数据库总对象数：" + count1);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		String[] arr1 = conn.userList(con, sql, 1);
		String[] arr2 = conn.userList(con, sql, 2);
		String[] arr3 = conn.userList(con, sql, 3);
		int len1 = arr1.length;
		for (int i = 0; i < len1; i++) {
			System.out.print(arr1[i] + "\t");
			System.out.print(arr2[i] + "\t");
			System.out.print(arr3[i] + "\t");
			System.out.println();
		}
		int count = conn.getTbrow();
		System.out.println("数据库总对象数：" + count);
		
	}

}