Java DButil 分解

package dbu;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import jdbc.Emp;
/**
 * jdbc utils
 * 
 */
public class DBUtils {
	Connection connection;
	ResultSet rSet;
	Statement statement;
	// 连接数据库
		public Connection getConnection() throws ClassNotFoundException, SQLException {
			Class.forName("oracle.jdbc.driver.OracleDriver");
			connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL","scott","tiger");
			System.out.println("success......");//随意去留
			return connection;
		}
	// 查询:查询一个就是对象，查询所有就是集合。
		public ResultSet query(String sql) throws ClassNotFoundException, SQLException {
			statement = connection.createStatement();
			rSet = statement.executeQuery(sql);
			return rSet;
		}
	// DML操作
		public int update(String sql) throws SQLException {
			statement =connection.createStatement();
			int i = statement.executeUpdate(sql);
			return i;
		}
	
	// 释放资源
		public void closed() throws SQLException {
			if (rSet != null) {
				rSet.close();
			}if (statement != null) {
				statement.close();
			}if (connection != null) {
				connection.close();
			}
		}
		
		public static void main(String[] args) {
			DBUtils dbUtils = new DBUtils();
			try {
				dbUtils.getConnection();
				int isRight = dbUtils.update("insert into dept values(01, 'Development', 'Shanghai')");
				System.out.println(isRight);
				ResultSet rSet = dbUtils.query("select * from emp");
				List<Emp> list = new ArrayList<>();
				Iterator<Emp> it = list.iterator();
				while (rSet.next()) {
					Emp emp = new Emp();
					emp.setEmpno(rSet.getInt("empno"));
					emp.setEname(rSet.getString("ename"));
					emp.setJob(rSet.getString("job"));
					list.add(emp);
				}	
				System.out.println(list.size());
			} catch (ClassNotFoundException e) {
				e.printStackTrace();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
}