javaweb 机房注意事项

jar包位置: D:\机房存放版本（javaDeveloperLibarys）
一定要Tomcat8.0 否则无法用注解
Mysql 账户:root 密码:空

jsp 设置编码格式步骤:
1 在Eclipse菜单栏选中【window】-【Perferences】

2.

项目结构

DBUtil类

package com.zyg.util;

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

//链接数据库
public class DBUtil {
     
	private static String user = "root";
	private static String password = "";
	private static String url = "jdbc:mysql://localhost:3306/exam?characterEncoding=utf-8";

	private static Connection connection;
	private static PreparedStatement statement;
	private static ResultSet rs;

	static {
     
		try {
     
			/**
			 * 通过路劲动态加载Driver驱动
			 */
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
     
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	// 定义getConnection返回数据库链接
	public static Connection getConnection() {
     

		try {
     
			connection = DriverManager.getConnection(url, user, password);
		} catch (SQLException e) {
     
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return connection;
	}

	// 关闭链接
	public static void closeAll() throws SQLException {
     
		if (rs != null) {
     
			rs.close();
		}
		if (statement != null) {
     
			statement.close();
		}
		if (connection != null) {
     
			connection.close();
		}
	}

	/**
	 * 封装基本的sql操作，查询以及其他操作 此处需要返回值ResultSet ,同时需要将sql作为参数，以及sql操作会传递参数需考虑
	 * 
	 * @param sql
	 * @throws SQLException
	 */

	public static ResultSet select(String sql, Object[] obj) {
     
		connection = getConnection();
		try {
     
			statement = connection.prepareStatement(sql);
//			将传递过来的参数进行遍历，全部的放到prepareStatement对象中进行预处理
			if (null != obj) {
     
				for (int i = 0; i < obj.length; i++) {
     
					System.out.println(obj[i]);
					statement.setObject(i + 1, obj[i]);
				}
			}

			// 参数预处理完毕后执行
			rs = statement.executeQuery();
		} catch (SQLException e) {
     
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return rs;

	}

	/**
	 * 更新、添加、删除需要执行后的返回值判断是否执行成功
	 * 
	 * @throws SQLException
	 */

	public static int update(String sql, Object[] obj) {
     

		connection = getConnection();

		try {
     
			statement = connection.prepareStatement(sql);
			if (null != obj) {
     
				for (int i = 0; i < obj.length; i++) {
     
					statement.setObject(i + 1, obj[i]);
				}
			}
		} catch (SQLException e) {
     
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		int i = 0;
		try {
     
			i = statement.executeUpdate();
		} catch (SQLException e) {
     
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return i;
	}
}