准备工作（1）

1. 准备工作

   • 新建maven web项目
   • 测试Tomcat
     

2. 导入相关依赖：
   

3. 数据库准备

supermarket:smbms_address,smbms_bill,smbms_provider,smbms_role,smbms_user

4. 构建相应的实体类

5. 编写配置文件

   db.properties
   

6. 编写数据库的公共类
   参考：https://blog.csdn.net/qq_42647047/article/details/116503457

     package com.test.dao;
   
     import java.io.IOException;
     import java.io.InputStream;
     import java.sql.*;
     import java.util.Properties;
   
     /**
      * 操作数据库的基类--静态类
      * @author Administrator
      *
      */
     public class BaseDao {
     	
     	static{//静态代码块,在类加载的时候执行
     		init();
     	}
     	
     	private static String driver;
     	private static String url;
     	private static String user;
     	private static String password;
     	
     	//初始化连接参数,从配置文件里获得
     	public static void init(){
     		Properties params=new Properties();
     		InputStream is=BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
     		try {
     			params.load(is);
     		} catch (IOException e) {
     			e.printStackTrace();
     		}
     		driver=params.getProperty("driver");
     		url=params.getProperty("url");
     		user=params.getProperty("user");
     		password=params.getProperty("password");
   
     	}   
     		
     	/**
     	 * 获取数据库连接
     	 * @return
     	 */
     	public static Connection getConnection(){
     		Connection connection = null;
     		try {
     			Class.forName(driver);
     			connection = DriverManager.getConnection(url, user, password);
     		} catch (Exception e) {
     			e.printStackTrace();
     		}
     		
     		return connection;
     	}
     	/**
     	 * 查询操作
     	 * @param connection
     	 * @param pstm
     	 * @param rs
     	 * @param sql
     	 * @param params
     	 * @return
     	 */
     	public static ResultSet execute(Connection connection,PreparedStatement pstm,ResultSet rs, String sql,Object[] params) throws Exception{
     		pstm = connection.prepareStatement(sql);
     		//向sql中的占位符加载参数Object[] params
     		for(int i = 0; i < params.length; i++){
     			pstm.setObject(i+1, params[i]);
     		}
     		rs = pstm.executeQuery();
     		return rs;
     	}
     	/**
     	 * 更新操作
     	 * @param connection
     	 * @param pstm
     	 * @param sql
     	 * @param params
     	 * @return
     	 * @throws Exception
     	 */
     	public static int execute(Connection connection,PreparedStatement pstm, String sql,Object[] params) throws Exception{
     		int updateRows = 0;
     		pstm = connection.prepareStatement(sql);
     		for(int i = 0; i < params.length; i++){
     			pstm.setObject(i+1, params[i]);
     		}
     		updateRows = pstm.executeUpdate();
     		return updateRows;
     	}
     	
     	/**
     	 * 释放资源
     	 * @param connection
     	 * @param pstm
     	 * @param rs
     	 * @return
     	 */
     	public static boolean closeResource(Connection connection,PreparedStatement pstm,ResultSet rs){
     		boolean flag = true;
     		if(rs != null){
     			try {
     				rs.close();
     				rs = null; //如果rs.close()没关上，让其等于null，使垃圾回收器自动回收。
     			} catch (SQLException e) {
     				e.printStackTrace();
     				flag = false;
     			}
     		}
     		if(pstm != null){
     			try {
     				pstm.close();
     				pstm = null;//GC回收
     			} catch (SQLException e) {
     				// TODO Auto-generated catch block
     				e.printStackTrace();
     				flag = false;
     			}
     		}
     		if(connection != null){
     			try {
     				connection.close();
     				connection = null;//GC回收
     			} catch (SQLException e) {
     				// TODO Auto-generated catch block
     				e.printStackTrace();
     				flag = false;
     			}
     		}
     		
     		return flag;
     	}
   
     }
   
   

7. 设置字符编码过滤器：在filter建一个类实现Filter接口，重写方法，将请求相应设置为utf-8编码，并在web.xml中配置字符编码过滤器

8. 导入静态资源css,js等资源，放在webapp文件夹下