JDBC访问数据库查询信息的步骤（硬编码格式）

1 Class.forName()加载驱动

2 DriverManager获取Connect连接

3 创建Statement执行SQL语句

4 返回ResultSet查询结果

5释放资源

package cn.tree.dao;

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

public class MenuDao {

	// 查询主目录
	public void getMainList() {
		Connection connection = null;
		Statement st = null;
		ResultSet rs = null;
		try {
			// 1、加载驱动
			Class.forName("com.mysql.jdbc.Driver");
			// 2、获取数据库连接
			connection = DriverManager.getConnection(
					"jdbc:mysql://127.0.0.1:3306/tree", "root", "123321");
			// 3、获取Statement对象，执行sql语句
			String sql = "select * from main";
			st = connection.createStatement();
			rs = st.executeQuery(sql);
			// 4、处理sql执行结果
			while (rs.next()) {
				int id = rs.getInt("id");
				String name = rs.getString("name");
				System.out.println("id: " + id + "\t" + "name: " + name);
			}
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				// 5、释放资源
				rs.close();
				st.close();
				connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	public static void main(String[] args) {
		MenuDao menuDao = new MenuDao();
		menuDao.getMainList();
	}
}