jdbc封装工具类（无连接池）

package com.huang;

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

public class DBUtil {

	private static final String driver = "com.mysql.jdbc.Driver";

	private static final String url = "jdbc:mysql://localhost:3306/test";

	private static final String username = "root";

	private static final String password = "root";

	public Connection conn = null;

	public PreparedStatement ps = null;

	public ResultSet rs = null;

	public Connection getConnection() {
		try {
			Class.forName(driver);
			return DriverManager.getConnection(url, username, password);
		} catch (Exception e) {
			System.out.println("get driver or connection error!");
			e.printStackTrace();
		}
		return null;
	}
	/**
	 * 通用查询方法
	 * @param sql
	 * @param obj
	 * @return
	 */
	public ResultSet query(String sql, Object[] obj) {
		conn = getConnection();
		if(conn == null) {
			return null;
		}
		try {
			ps = conn.prepareStatement(sql);

			if(obj!=null && obj.length>0) {

				for (int i = 0; i < obj.length; i++) {
					ps.setObject(i+1, obj[i]);
				}
			}

			return ps.executeQuery();

		} catch (Exception e) {

		}
		return null;
	}

	public void close() {
		if(rs!=null) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if(ps!=null) {
			try {
				ps.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
		if(conn!=null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	public static void main(String[] args) throws Exception {
		DBUtil dbUtil = new DBUtil();
		dbUtil.rs = dbUtil.query("select * from user_info where id = ?", new Object[] {"1"});
		while(dbUtil.rs.next()) {
			System.out.println(dbUtil.rs.getString(1) + "--" + dbUtil.rs.getString(2));
		}
		dbUtil.close();
	}

}